A method and device for quantizing and decoding a synthetic aperture radar complex image

Abstract

The present invention discloses a method and apparatus for quantizing and decoding synthetic aperture radar complex images. The method includes: obtaining a set of synthetic aperture radar scattering response data of a typical scene under a synthetic aperture radar sensor and the original complex image value of any pixel to be quantized; calculating the basic data set from the set of synthetic aperture radar scattering response data; performing peak normalization uniform quantization calculation after logarithmic transformation on the basic data set and the original complex image value of any pixel to be quantized to obtain the quantized complex image value of any pixel; and performing decoding calculation on the stored quantized complex image value of any pixel to obtain the original complex image value of any pixel. It can be seen that the present invention is beneficial to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reducing the error effects of quantization on power and phase.

Description

Technical Field

[0001] The present invention relates to the technical field of complex image quantization, and in particular to a method and device for synthetic aperture radar complex image quantization and decoding. Background Art

[0002] Synthetic Aperture Radar (SAR) is an active microwave sensor that stores the electromagnetic wave response of ground targets as a complex image, which requires quantization processing. The currently common SAR image quantization method is uniform quantization after peak normalization, that is, the maximum value of the electromagnetic wave response within the entire scene is obtained, and through uniform quantization, the quantization result is stored. In this uniform quantization method, for strong targets and weak targets, the quantization noise power introduced is the same, but the quantization signal-to-noise ratio is different. The quantization signal-to-noise ratio of weak targets is low, and that of strong targets is high. Therefore, for radiation accuracy, the loss of strong targets is small, and the loss of weak targets is large. More importantly, the power and phase errors caused by quantization are relatively large at low quantization levels, and the higher the quantization level, the smaller and more stable the power and phase errors become.

[0003] Considering the quantization signal-to-noise ratio, quantization power error, and quantization phase error comprehensively, in this uniform quantization, low quantization levels (0 - 50 levels) should be used as little as possible. However, the larger the dynamic range of the SAR image, especially the ratio of the amplitude peak to the mean value, the larger the pixel ratio occupied by low quantization levels. But with the continuous improvement of SAR sensor performance and increasing resolution, the current dynamic range of the SAR amplitude response is getting larger and larger. As shown in Figure 8 、 9 , more than half of the dynamic range of the scene exceeds the 93dB quantization dynamic range of 16 bits. There will inevitably be losses in uniform quantization; moreover, the difference between the peak and the mean value exceeds 45dB, and there will inevitably be a lot of data falling into low quantization levels with relatively poor quantization performance. Therefore, the peak normalization uniform quantization method is no longer suitable. How to perform reasonable quantization to relatively losslessly maintain amplitude and phase information and ensure absolute radiation accuracy and the phase accuracy required for subsequent interference applications is an urgent problem to be solved.

[0004] Therefore, a method and device for synthetic aperture radar complex image quantization and decoding are provided to ensure the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduce the error impact of quantization on power and phase. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method and device for quantifying and decoding synthetic aperture radar complex images, which can relatively losslessly preserve amplitude and phase information, ensure absolute radiation accuracy and the phase accuracy required for subsequent interference applications, is beneficial to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduces the error impact of quantization on power and phase.

[0006] To solve the above technical problem, a first aspect of an embodiment of the present invention discloses a method for quantifying and decoding synthetic aperture radar complex images, the method comprising:

[0007] S1, obtaining a set of SAR scattering response data of a typical scene under an SAR sensor, and the original complex image value of any pixel point to be quantified; the set of SAR scattering response data includes SAR scattering response data of several typical scenes; the original complex image value includes the real part original value of the scattering response and the imaginary part original value of the scattering response;

[0008] S2, calculating the set of SAR scattering response data to obtain a basic data set;

[0009] S3, performing logarithmic transformation-based peak normalization uniform quantization calculation on the basic data set and the original complex image value of any pixel point to be quantified to obtain the quantized complex image value of any pixel point; the quantized complex image value includes the real part quantized value of the scattering response and the imaginary part quantized value of the scattering response;

[0010] S4, performing decoding calculation on the stored quantized complex image value of any pixel point to obtain the original complex image value of any pixel point.

[0011] As an optional implementation manner, in the first aspect of the embodiment of the present invention, the calculating the set of SAR scattering response data to obtain a basic data set includes:

[0012] S21, performing a modulus operation on the set of SAR scattering response data to obtain the maximum amplitude dB value of the SAR scattering response and the minimum amplitude dB value of the SAR scattering response;

[0013] S22, performing expansion calculation on the maximum amplitude dB value of the SAR scattering response to obtain the set maximum amplitude threshold dB value;

[0014] S23, performing expansion calculation on the minimum amplitude dB value of the SAR scattering response to obtain the set minimum amplitude threshold dB value and the original minimum amplitude threshold value;

[0015] S24, performing weight calculation on the set maximum amplitude threshold dB value and the set minimum amplitude threshold dB value to obtain a quantization weight, and the calculation expression is:

[0016] Weight=(AmpMaxThres dB -AmpMinThres dB ) / X

[0017] X=2 J-1 -1

[0018] Wherein, X is the quantization order, J is the quantization bit number, Weight is the quantization weight, AmpMaxThres dB is the dB value of the maximum amplitude threshold setting, AmpMinThres dB is the dB value of the minimum amplitude threshold setting.

[0019] As an optional implementation manner, in the first aspect of the embodiments of the present invention, the modulo operation on the SAR scattering response data set to obtain the maximum amplitude dB value and the minimum amplitude dB value of the SAR scattering response includes:

[0020] S211, perform a modulo operation on each point of the SAR scattering response data set to obtain the amplitude value of the SAR scattering response, and the calculation expression is:

[0021] Amp=sqrt(I 2 +Q 2 )

[0022] Wherein, I is the real part original value of the scattering response of any pixel point, Q is the imaginary part original value of the scattering response of any pixel point, sqrt(·) is the square root calculation, and Amp is the amplitude value of the SAR scattering response of any pixel point;

[0023] S212, perform statistical analysis on the SAR scattering response amplitude value to obtain the maximum amplitude value and the minimum amplitude value of the SAR scattering response;

[0024] S213, perform dB value conversion calculation on the maximum amplitude value and the minimum amplitude value of the SAR scattering response to obtain the maximum amplitude dB value and the minimum amplitude dB value of the SAR scattering response, and the calculation expression is:

[0025] AmpMax dB =20*log 10 (AmpMax)

[0026] AmpMin dB =20*log 10 (AmpMin)

[0027] Wherein, AmpMax is the maximum amplitude value of the SAR scattering response, AmpMin is the minimum amplitude value of the SAR scattering response, AmpMax dB is the maximum amplitude dB value of the SAR scattering response, AmpMin dB is the minimum amplitude dB value of the SAR scattering response, log 10 (·) is the logarithmic function with base 10.

[0028] As an alternative implementation, in the first aspect of the embodiments of the present invention, the expansion calculation of the maximum amplitude dB value of the SAR scattering response to obtain the maximum amplitude threshold setting dB value includes:

[0029] S221, preset the maximum amplitude protection band dB value; the maximum amplitude protection band dB value is an integer multiple of 10;

[0030] S222, round up the maximum amplitude dB value of the SAR scattering response to obtain the maximum amplitude rounded dB value;

[0031] S223, calculate the maximum amplitude protection band dB value and the maximum amplitude rounded dB value to obtain the maximum amplitude threshold setting dB value, and the calculation expression is:

[0032] AmpMaxThres dB =AmpMaxProTape dB +AmpMaxRound dB

[0033] Wherein, AmpMaxThres dB is the maximum amplitude threshold setting dB value, AmpMaxProTape dB is the maximum amplitude protection band dB value, AmpMaxRound dB is the maximum amplitude rounded dB value.

[0034] As an alternative implementation, in the first aspect of the embodiments of the present invention, the expansion calculation of the minimum amplitude dB value of the SAR scattering response to obtain the minimum amplitude threshold setting dB value and the minimum amplitude threshold original value includes:

[0035] S231, preset the minimum amplitude protection band dB value; the minimum amplitude protection band dB value is an integer multiple of 10;

[0036] S232, round down the minimum amplitude dB value of the SAR scattering response to obtain the minimum amplitude rounded dB value;

[0037] S233. Calculate the minimum amplitude threshold setting dB value by calculating the minimum amplitude protection band dB value and the minimum amplitude rounded dB value. The calculation expression is:

[0038] AmpMinThres dB = AmpMinProTape dB + AmpMinRound dB

[0039] In the formula, AmpMinThres dB is the minimum amplitude threshold setting dB value, AmpMinProTape dB is the minimum amplitude protection band dB value, and AmpMinRound dB is the minimum amplitude rounded dB value;

[0040] S234. Perform an inverse calculation of the original value on the minimum amplitude threshold setting dB value to obtain the minimum amplitude threshold original value. The inverse calculation expression of the original value is:

[0041]

[0042] In the formula, AmpMinThres is the minimum amplitude threshold original value.

[0043] As an optional implementation manner, in the first aspect of the embodiments of the present invention, the calculation of the complex image quantization value of any pixel point by performing peak normalization uniform quantization on the logarithmically transformed basic data set and the complex image original value of any pixel point to be quantized includes:

[0044] S31. Take the absolute values of the real part original value and the imaginary part original value of the scattering response of any pixel point to obtain the real part absolute value and the imaginary part absolute value;

[0045] S32. Add the real part absolute value and the imaginary part absolute value to the minimum amplitude threshold original value respectively, and perform a dB value calculation to obtain the real part offset dB value and the imaginary part offset dB value. The calculation expression is:

[0046] I bias = 20 * log 10 [abs(I) + AmpMinThres]

[0047] Q bias = 20 * log 10 [abs(Q) + AmpMinThres]

[0048] In the formula, I bias is the real part offset dB value, and Q biasis the dB value of the imaginary part bias, and abs(·) is the absolute value function;

[0049] S33. Subtract the dB value of the real part bias and the dB value of the imaginary part bias of the scattering response from the minimum amplitude threshold setting dB value respectively to obtain the updated dB value of the real part and the updated dB value of the imaginary part. The calculation expression is:

[0050] I new = I bias - AmpMinThres dB

[0051] Q new = Q bias - AmpMinThres dB

[0052] In the formula, I new is the updated dB value of the real part, and Q new is the updated dB value of the imaginary part;

[0053] S34. Divide the updated dB value of the real part and the updated dB value of the imaginary part of the scattering response by the quantization weight respectively, and after rounding calculation, multiply them by the sign bits of the original value of the real part and the original value of the imaginary part of the scattering response respectively to obtain the quantized value of the real part of the complex image and the quantized value of the imaginary part of the complex image of this pixel point. The calculation expression is:

[0054]

[0055]

[0056] In the formula, Weight is the quantization weight, I Jbit is the quantized value of the real part of the complex image, Q Jbit is the quantized value of the imaginary part of the complex image, round(·) is the rounding function, and sign(·) is the sign function.

[0057] As an optional implementation manner, in the first aspect of the embodiments of the present invention, the decoding calculation of the quantized value of the complex image of any pixel point stored to obtain the original value of the complex image of any pixel point includes:

[0058] S41. Take the absolute value of the quantized value of the real part and the quantized value of the imaginary part of the stored complex image respectively to obtain the absolute value of the real part quantization and the absolute value of the imaginary part quantization;

[0059] S42. Multiply the absolute value of the real part quantization and the absolute value of the imaginary part quantization by the quantization weight respectively, and add the minimum amplitude threshold setting dB value to obtain the dB value of the real part bias and the dB value of the imaginary part bias. The expression is:

[0060] I bias = abs(I Jbit ) * Weight + AmpMinThres dB

[0061] Q bias = abs(Q Jbit ) * Weight + AmpMinThres dB

[0062] S43, calculate the power value with base 10 for the real part offset dB value and the imaginary part offset dB value, then subtract the original minimum amplitude threshold value from the power value, and then multiply by the sign bit of the real part quantization value and the sign bit of the imaginary part quantization value respectively to obtain the original real part value and the original imaginary part value of the scattering response. The expression is:

[0063]

[0064]

[0065] In the formula, pow(10, ·) is the exponential function with base 10.

[0066] In the second aspect of the embodiments of the present invention, a synthetic aperture radar complex image quantization and decoding device is disclosed. The device includes:

[0067] An acquisition module, which acquires a set of SAR scattering response data of a typical scene under an SAR sensor and the original complex image value of any pixel point to be quantified; the set of SAR scattering response data includes SAR scattering response data of several typical scenes; the original complex image value includes the original real part value and the original imaginary part value of the scattering response;

[0068] A first quantization module, which calculates the basic data set for the set of SAR scattering response data;

[0069] A second quantization module, which performs peak-normalized uniform quantization calculation after logarithmic transformation on the basic data set and the original complex image value of any pixel point to be quantified to obtain the complex image quantization value of any pixel point; the complex image quantization value includes the real part quantization value and the imaginary part quantization value of the scattering response;

[0070] A decoding module, which performs decoding calculation on the stored complex image quantization value of any pixel point to obtain the original complex image value of any pixel point.

[0071] In the third aspect of the present invention, another synthetic aperture radar complex image quantization and decoding device is disclosed. The device includes:

[0072] A memory storing executable program code;

[0073] A processor coupled to the memory;

[0074] The processor calls the executable program code stored in the memory and executes some or all of the steps in the synthetic aperture radar complex image quantization and decoding method disclosed in the first aspect of the embodiments of the present invention.

[0075] The fourth aspect of the present invention discloses a computer storage medium storing computer instructions, which are used to execute some or all of the steps in the synthetic aperture radar complex image quantization and decoding method disclosed in the first aspect of the embodiments of the present invention when the computer instructions are called.

[0076] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0077] In the embodiments of the present invention, a set of SAR scattering response data of a typical scene under an SAR sensor and the complex image original value of any pixel point to be quantized are obtained; the basic data set is obtained by calculating the SAR scattering response data set; the peak-normalized uniform quantization calculation after logarithmic transformation is performed on the basic data set and the complex image original value of any pixel point to be quantized to obtain the complex image quantization value of any pixel point; the decoding calculation is performed on the stored complex image quantization value of any pixel point to obtain the complex image original value of any pixel point. It can be seen that the present invention is beneficial to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduces the error influence of quantization on power and phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0079] Figure 1 is a schematic flow chart of a synthetic aperture radar complex image quantization and decoding method disclosed in an embodiment of the present invention;

[0080] Figure 2 is a schematic structural diagram of a synthetic aperture radar complex image quantization and decoding device disclosed in an embodiment of the present invention;

[0081] Figure 3 is a schematic structural diagram of another synthetic aperture radar complex image quantization and decoding device disclosed in an embodiment of the present invention;

[0082] Figure 4 It is a curve graph of the quantization signal-to-noise ratio of different amplitude Levels of different dynamic range images disclosed in the embodiments of the present invention;

[0083] Figure 5 It is a curve graph of the influence on power after quantization of different amplitude Levels of different dynamic range images disclosed in the embodiments of the present invention;

[0084] Figure 6 It is a curve graph of the influence on phase after quantization of different amplitude Levels of different dynamic range images disclosed in the embodiments of the present invention;

[0085] Figure 7 It is a curve graph of the proportion of the number of pixels occupied by the quantization level [0 - 50] under different ratios of peak value to mean value disclosed in the embodiments of the present invention;

[0086] Figure 8 It is a bar graph of the difference between the maximum value and the minimum value of the amplitude of the scattering response per scene disclosed in the embodiments of the present invention;

[0087] Figure 9 It is a bar graph of the difference between the peak value and the mean value of the amplitude of the scattering response per scene disclosed in the embodiments of the present invention;

[0088] Figure 10 It is a distribution graph of the quantization signal-to-noise ratio of different amplitude Levels of different dynamic range images disclosed in the embodiments of the present invention;

[0089] Figure 11 It is a distribution graph of the influence on power after quantization of different amplitude Levels of different dynamic range images disclosed in the embodiments of the present invention;

[0090] Figure 12 It is a distribution graph of the influence on phase after quantization of different amplitude Levels of different dynamic range images disclosed in the embodiments of the present invention. Detailed implementation manners

[0091] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0092] In the description and claims of the present invention and the above-mentioned drawings, terms such as "first", "second", etc. are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, device, product or equipment that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include steps or units not listed, or may optionally further include other steps or units inherent to these processes, methods, products or equipment.

[0093] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present invention. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0094] The present invention discloses a method and device for quantifying and decoding synthetic aperture radar complex images, which can relatively losslessly maintain amplitude and phase information, ensure absolute radiation accuracy and the phase accuracy required for subsequent interference applications, facilitate ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduce the error effects of quantization on power and phase. In addition, decoding is performed based on the quantized output complex image, and the true scattering response of the ground object can be relatively faithfully restored. The following will be described in detail separately.

[0095] Synthetic Aperture Radar (SAR) is an active microwave sensor. The SAR sensor emits electromagnetic wave pulses at a certain pulse repetition frequency on the platform and receives the reflected echoes from the ground. As the platform moves, the echo pulses within the antenna beam illumination range are sequentially recorded. Therefore, the original signal collected by the radar is not an image and must undergo complex two-dimensional compression imaging processing to compress the echo energy expanded by each point target in two directions within the illumination range into the energy of a resolution unit before it can become a visible image. The SAR image is actually a collection of some data samples, and each pixel represents the electromagnetic wave response of the actual ground object point target at that ground position, which is represented in the form of a complex number containing a real part and an imaginary part. The amplitude and phase information of the corresponding ground object within the illumination range can be extracted from the complex image. The amplitude information corresponds to the backscattering intensity of the ground target to the radar wave, and the phase information corresponds to the round-trip propagation distance between the SAR platform and the ground target. Therefore, the SAR complex image is the basis for SAR remote sensing applications.

[0096] The currently common SAR image quantization method is uniform quantization after peak normalization, that is, the maximum value of the electromagnetic wave response within the entire scene is obtained, and through uniform quantization, the quantization result is stored. For this uniform quantization method, the quantization noise power introduced for strong targets and weak targets is the same, but the quantization signal-to-noise ratio is different. The quantization signal-to-noise ratio of weak targets is low, and that of strong targets is high. Therefore, for radiation accuracy, the loss of strong targets is small, and the loss of weak targets is large, as Figure 4 shown. Figure 4 Figure 4 shows the quantization signal-to-noise ratio of images with different dynamic ranges at different quantization levels [0 - 32767] (the change is relatively large from 0 to 50 levels, and the signal-to-noise ratio is greater than 40 dB after 50 levels, and the signal-to-noise ratio tends to be stable as the number of levels increases). More importantly, the power and phase errors caused by quantization at low quantization levels are relatively large. The higher the quantization level, the smaller and more stable the power and phase errors, as Figure 5 and 6 shown. Figure 5 Figure 5 shows the power loss caused by quantization at different quantization levels. The average power error caused by quantization above 40 levels is close to 0 dB, Figure 6 Figure 6 shows the phase loss caused by quantization at different quantization levels. The standard deviation of the phase error introduced by quantization above 100 levels is less than 0.2 degrees.

[0097] Considering the quantization signal-to-noise ratio, quantization power error, and quantization phase error comprehensively, in this uniform quantization, low quantization levels (0 - 50 levels) should be used as little as possible. However, the larger the dynamic range of the SAR image, especially the larger the ratio of the amplitude peak to the mean value, the larger the pixel ratio occupied by low quantization levels, as Figure 7 shown. Figure 7 Figure 7 shows the relationship between the difference between the peak / mean value and the proportion of the first 50 quantization levels in different dynamic ranges through simulation statistics. It can be seen that if the number of pixels in the first 50 quantization levels after quantization does not exceed 0.1%, the ratio of the peak to the mean value should not exceed 45 dB. However, with the continuous improvement of SAR sensor performance and the increase in resolution, the current dynamic range of the SAR amplitude response is getting larger and larger, as Figure 8 and 9 shown. Half of the dynamic range of the scene exceeds the 93 dB quantization dynamic range of 16 bits, and there will inevitably be losses in uniform quantization; moreover, the difference between the peak and the mean value exceeds 45 dB, and there will inevitably be a lot of data falling in the low quantization levels with poor quantization performance. Therefore, the peak normalization uniform quantization method is no longer suitable. Figure 8 Figure 8 shows the statistical value of the difference between the maximum amplitude and the minimum amplitude of the scattered response amplitude in different actual scenes, that is, the dynamic range value (unit: dB); Figure 9 Figure 9 shows the statistical value of the difference between the amplitude peak and the mean value of the scattered response in different actual scenes (unit: dB).

[0098] The currently commonly used peak normalization uniform quantization method has problems such as poor quantization signal-to-noise ratio, large quantization power error, and large phase error at low quantization levels. Moreover, with the improvement of the performance of SAR payloads, the dynamic range of ground object scattering responses has been continuously increasing, and this problem has seriously affected the accuracy of the amplitude and phase information extracted from images. The peak normalization uniform quantization and decoding method based on logarithmic transformation proposed by the present invention can not only ensure the stability of the quantization signal-to-noise ratio under different signal powers, but also greatly reduce the error effects of quantization on power and phase, as shown in Figure 10 , Figure 11 , Figure 12 . They are respectively the quantization signal-to-noise ratio, the influence on power, and the influence on phase after quantization of different signal powers under different dynamic ranges of a certain SAR data of the present invention. After the signal power is greater than -20 dB, the quantization signal-to-noise ratio is better than 30 dB, the influence on power is less than 0.01 dB, and the influence on phase is less than 1 degree. Here, the minimum amplitude value of the response of a certain type of SAR obtained through statistics is basically greater than -20 dB, and the AmpMinThres_dB set during quantization is -40 dB. The method for quantizing synthetic aperture radar complex images for maintaining amplitude and phase information of the present invention fully considers a series of problems that may occur during the implementation process, and proposes to determine the minimum value of the logarithmic transformation by setting a specific guard band. First, it avoids the problem that the value close to zero becomes close to negative infinity after taking the logarithm. Second, it avoids the problem that the entire dynamic range is too large due to the minimum value being too small, resulting in a large quantization level and causing a large radiation error. Third, it avoids the problem that the minimum value is too large and higher than the system background noise, thereby introducing errors.

[0099] Embodiment 1

[0100] Please refer to Figure 1 , Figure 1 , which is a schematic flowchart of a method for quantizing and decoding synthetic aperture radar complex images disclosed in an embodiment of the present invention. Among them, Figure 1 The described method for quantizing and decoding synthetic aperture radar complex images is applied to a complex image quantization system, such as a local server or a cloud server for managing the quantization and decoding of synthetic aperture radar complex images, etc., which is not limited in the embodiments of the present invention. As shown in Figure 1 , the method for quantizing and decoding synthetic aperture radar complex images may include the following operations:

[0101] S1, obtaining a set of SAR scattering response data of a typical scene under an SAR sensor, and the original complex image value of any pixel point to be quantized.

[0102] In the embodiments of the present invention, the above-mentioned set of SAR scattering response data includes SAR scattering response data of several typical scenes.

[0103] In the embodiments of the present invention, the above-mentioned complex image raw values include the real part raw value of the scattering response and the imaginary part raw value of the scattering response.

[0104] S2. Calculate the SAR scattering response data set to obtain a basic data set.

[0105] S3. Perform peak normalization uniform quantization calculation on the basic data set after logarithmic transformation to obtain the complex image quantization value of any pixel point.

[0106] In the embodiments of the present invention, the above-mentioned complex image quantization values include the real part quantization value of the scattering response and the imaginary part quantization value of the scattering response.

[0107] S4. Perform decoding calculation on the stored complex image quantization values to obtain the complex image raw values of any pixel point; the complex image raw values include the real part raw value of the scattering response and the imaginary part raw value of the scattering response.

[0108] Optionally, typical scenarios include but are not limited to plains, mountains, towns, ports, and sea surfaces, covering strong scattering and weak scattering ground object types.

[0109] Optionally, the dB value is to obtain the power value Amp for a certain amplitude value Amp dB That is, Amp dB = 20 * log 10 (Amp).

[0110] It can be seen that implementing the synthetic aperture radar complex image quantization and decoding method described in the embodiments of the present invention can relatively losslessly preserve amplitude and phase information, ensure absolute radiation accuracy and the phase accuracy required for subsequent interference applications, is conducive to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduces the error impact of quantization on power and phase.

[0111] In an optional embodiment, the above-mentioned calculation of the SAR scattering response data set to obtain a basic data set includes:

[0112] S21. Perform a modulus operation on the SAR scattering response data set to obtain the maximum amplitude dB value of the SAR scattering response and the minimum amplitude dB value of the SAR scattering response;

[0113] S22. Perform an expansion calculation on the maximum amplitude dB value of the SAR scattering response to obtain the maximum amplitude threshold setting dB value;

[0114] S23. Perform an expansion calculation on the minimum amplitude dB value of the SAR scattering response to obtain the minimum amplitude threshold setting dB value and the minimum amplitude threshold raw value;

[0115] S24. Calculate the weights for the maximum amplitude threshold dB value and the minimum amplitude threshold dB value to obtain the quantization weights. The calculation expression is as follows:

[0116] Weight = (AmpMaxThres dB - AmpMinThres dB ) / X

[0117] X = 2 J-1 - 1

[0118] In the formula, X is the quantization order, J is the quantization bit number, Weight is the quantization weight, AmpMaxThres dB is the maximum amplitude threshold setting dB value, and AmpMinThres dB is the minimum amplitude threshold setting dB value.

[0119] Optionally, taking 16 - bit quantization as an example, excluding the sign bits of the real and imaginary parts, the quantization order is:

[0120] 2 15 - 1 = 32767

[0121] Calculate the quantization weights:

[0122] Weight = (AmpMaxThres dB - AmpMinThres dB ) / 32767.

[0123] It can be seen that implementing the synthetic aperture radar complex image quantization and decoding method described in the embodiments of the present invention can perform extended calculations on the maximum amplitude dB value and the minimum amplitude dB value of the SAR scattering response, which is beneficial to ensuring the stability of the quantization signal - to - noise ratio under different signal powers, and at the same time greatly reduces the error effects of quantization on power and phase.

[0124] In another optional embodiment, the above - mentioned modulo operation on the SAR scattering response data set to obtain the maximum amplitude dB value and the minimum amplitude dB value of the SAR scattering response includes:

[0125] S211. Perform a point - by - point modulo operation on the SAR scattering response data set to obtain the amplitude value of the SAR scattering response. The calculation expression is as follows:

[0126] Amp = sqrt(I 2 + Q 2 )

[0127] Wherein, I is the original real value of the scattering response of any pixel point, Q is the original imaginary value of the scattering response of any pixel point, sqrt(·) is the square root calculation, and Amp is the amplitude value of the SAR scattering response of any pixel point;

[0128] S212. Perform statistical analysis on the SAR scattering response amplitude value to obtain the maximum amplitude value of the SAR scattering response and the minimum amplitude value of the SAR scattering response;

[0129] S213. Perform dB value conversion calculation on the maximum amplitude value of the SAR scattering response and the minimum amplitude value of the SAR scattering response to obtain the maximum amplitude dB value of the SAR scattering response and the minimum amplitude dB value of the SAR scattering response. The calculation expression is:

[0130] AmpMax dB = 20 * log 10 (AmpMax)

[0131] AmpMin dB = 20 * log 10 (AmpMin)

[0132] Wherein, AmpMax is the maximum amplitude value of the SAR scattering response, AmpMin is the minimum amplitude value of the SAR scattering response, AmpMax dB is the maximum amplitude dB value of the SAR scattering response, AmpMin dB is the minimum amplitude dB value of the SAR scattering response, and log 10 (·) is the logarithmic function with base 10.

[0133] It can be seen that implementing the synthetic aperture radar complex image quantization and decoding method described in the embodiments of the present invention can perform statistical analysis on the SAR scattering response amplitude value to obtain the maximum amplitude value of the SAR scattering response and the minimum amplitude value of the SAR scattering response, which is beneficial to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reducing the error effects of quantization on power and phase.

[0134] In another optional embodiment, the above-mentioned expansion calculation is performed on the maximum amplitude dB value of the SAR scattering response to obtain the maximum amplitude threshold setting dB value, including:

[0135] S221. Preset the maximum amplitude protection band dB value; the maximum amplitude protection band dB value is an integer multiple of 10;

[0136] S222. Round up the maximum amplitude dB value of the SAR scattering response to an integer to obtain the maximum amplitude rounded dB value;

[0137] S223. Calculate the dB value of the maximum amplitude guard band and the rounded dB value of the maximum amplitude to obtain the dB value for setting the maximum amplitude threshold. The calculation formula is:

[0138] AmpMaxThres dB = AmpMaxProTape dB + AmpMaxRound dB

[0139] In the formula, AmpMaxProTape dB is the dB value of the maximum amplitude guard band, and AmpMaxRound dB is the rounded dB value of the maximum amplitude.

[0140] Optionally, based on AmpMin dB retain a certain guard band (such as a 20 dB guard band) and expand it in the direction of decreasing values, and take an integer multiple of 10 to obtain the minimum amplitude threshold setting AmpMinThres dB and the corresponding original amplitude threshold AmpMinThres. For example, if the minimum amplitude value AmpMin dB obtained in the step is -17 dB, then set AmpMinThres dB to -40 dB, and AmpMinThres is

[0141] Optionally, based on AmpMax dB retain a certain guard band (such as a 20 dB guard band) and expand it in the direction of increasing values, and take an integer multiple of 10 to obtain the maximum amplitude threshold setting AmpMaxThres dB . For example, if the maximum amplitude value AmpMax dB obtained in the step is 111 dB, then set AmpMaxThres dB to 140 dB.

[0142] It can be seen that implementing the synthetic aperture radar complex image quantization and decoding method described in the embodiments of the present invention can preset the dB value of the maximum amplitude guard band, which is more conducive to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduces the error effects of quantization on power and phase.

[0143] In another optional embodiment, the above-mentioned extended calculation of the minimum amplitude dB value of the SAR scattering response to obtain the minimum amplitude threshold setting dB value and the original value of the minimum amplitude threshold includes:

[0144] S231. Preset the dB value of the minimum amplitude guard band; the dB value of the minimum amplitude guard band is an integer multiple of 10;

[0145] S232, round down the minimum amplitude dB value of the SAR scattering response to obtain the rounded minimum amplitude dB value;

[0146] S233, calculate the minimum amplitude protection band dB value and the rounded minimum amplitude dB value to obtain the minimum amplitude threshold setting dB value. The calculation expression is:

[0147] AmpMinThres dB = AmpMinProTape dB + AmpMinRound dB

[0148] In the formula, AmpMinProTape dB is the minimum amplitude protection band dB value, and AmpMinRound dB is the rounded minimum amplitude dB value;

[0149] S234, perform reverse calculation of the original value on the minimum amplitude threshold setting dB value to obtain the original minimum amplitude threshold value. The reverse calculation expression of the original value is:

[0150]

[0151] In the formula, AmpMinThres is the original minimum amplitude threshold value.

[0152] It can be seen that implementing the synthetic aperture radar complex image quantization and decoding method described in the embodiments of the present invention can preset the minimum amplitude protection band dB value, which is more conducive to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduces the error effects of quantization on power and phase.

[0153] In another optional embodiment, the above-mentioned peak normalization uniform quantization calculation after logarithmic transformation of the basic data set to obtain the complex image quantization value of any pixel point includes:

[0154] S31, take the absolute values of the real part original value and the imaginary part original value of the scattering response of any pixel point respectively to obtain the real part absolute value and the imaginary part absolute value;

[0155] S32, add the real part absolute value and the imaginary part absolute value to the original minimum amplitude threshold value respectively and perform dB value calculation to obtain the real part offset dB value and the imaginary part offset dB value. The calculation expressions are:

[0156] I bias = 20 * log 10 [abs(I) + AmpMinThres]

[0157] Q bias = 20 * log10 [abs(Q) + AmpMinThres]

[0158] Wherein, I bias is the real - part offset dB value, Q bias is the imaginary - part offset dB value, abs(·) is the absolute - value function;

[0159] S33: Subtract the minimum amplitude threshold setting dB value from the real - part offset dB value and the imaginary - part offset dB value of the scattering response respectively to obtain the real - part updated dB value and the imaginary - part updated dB value. The calculation expression is:

[0160] I new = I bias - AmpMinThres dB

[0161] Q new = Q bias - AmpMinThres dB

[0162] Wherein, I new is the real - part updated dB value, Q new is the imaginary - part updated dB value;

[0163] S34: Divide the real - part updated dB value and the imaginary - part updated dB value of the scattering response by the quantization weight respectively, and after rounding and taking the integer calculation, multiply them by the sign bits of the original real - part value and the original imaginary - part value of the scattering response respectively to obtain the real - part quantization value of the complex - number image of the pixel point and the imaginary - part quantization value of the complex - number image. The calculation expression is:

[0164]

[0165]

[0166] Wherein, Weight is the quantization weight, I Jbit is the real - part quantization value of the complex - number image, Q Jbit is the imaginary - part quantization value of the complex - number image, round(·) is the rounding - off and taking - integer function, sign(·) is the sign function.

[0167] It can be seen that implementing the synthetic aperture radar complex - number image quantization and decoding method described in the embodiments of the present invention can perform peak - normalization uniform quantization calculation on the basis data set after logarithmic transformation, which is more beneficial to ensuring the stability of the quantization signal - to - noise ratio under different signal powers, and at the same time greatly reduces the error influence of quantization on power and phase.

[0168] In another optional embodiment, the above - mentioned decoding calculation of the stored complex - number image quantization value to obtain the original value of the complex - number image of any pixel point includes:

[0169] S41. Take the absolute values of the real - part quantization value and the imaginary - part quantization value of the stored complex - number image respectively to obtain the real - part quantization absolute value and the imaginary - part quantization absolute value.

[0170] S42. Multiply the real - part quantization absolute value and the imaginary - part quantization absolute value by the quantization weight respectively, and add the minimum amplitude threshold setting dB value to obtain the real - part offset dB value and the imaginary - part offset dB value. The expressions are as follows:

[0171] I bias = abs(I Jbit ) * Weight+AmpMinThres dB

[0172] Q bias = abs(Q Jbit ) * Weight+AmpMinThres dB

[0173] S43. Perform the power - of - 10 calculation on the real - part offset dB value and the imaginary - part offset dB value, then subtract the minimum amplitude threshold original value from the power value, and multiply by the sign bit of the real - part quantization value and the sign bit of the imaginary - part quantization value respectively to obtain the real - part original value of the scattering response and the imaginary - part original value of the scattering response. The expressions are as follows:

[0174]

[0175]

[0176] In the formula, pow(10, ·) is the exponential function with base 10.

[0177] It can be seen that implementing the synthetic aperture radar complex - number image quantization and decoding method described in the embodiments of the present invention can perform decoding calculations on the quantization values of the stored complex - number images to obtain the original values of the complex - number images of any pixel point, which is more conducive to ensuring the stability of the quantization signal - to - noise ratio under different signal powers, and at the same time greatly reduces the error effects of quantization on power and phase.

[0178] Embodiment 2

[0179] Please refer to Figure 2 , Figure 2 which is a schematic structural diagram of a synthetic aperture radar complex - number image quantization and decoding device disclosed in the embodiments of the present invention. Among them, Figure 2 the described device can be applied to a complex - number image quantization system, such as a local server or a cloud server for synthetic aperture radar complex - number image quantization and decoding management, etc., which is not limited in the embodiments of the present invention. As Figure 2 shown, the device may include:

[0180] An acquisition module 201 acquires a SAR scattering response data set of a typical scenario under a SAR sensor and the complex image raw value of any pixel to be quantified; the SAR scattering response data set includes SAR scattering response data of several typical scenarios; the complex image raw value includes the real part raw value of the scattering response and the imaginary part raw value of the scattering response;

[0181] A first quantization module 202 calculates the SAR scattering response data set to obtain a basic data set;

[0182] A second quantization module 203 performs peak normalization uniform quantization calculation on the basic data set after logarithmic transformation to obtain the complex image quantization value of any pixel; the complex image quantization value includes the real part quantization value of the scattering response and the imaginary part quantization value of the scattering response;

[0183] A decoding module 204 performs decoding calculation on the stored complex image quantization value to obtain the complex image raw value of any pixel; the complex image raw value includes the real part raw value of the scattering response and the imaginary part raw value of the scattering response.

[0184] It can be seen that implementing Figure 2 the described synthetic aperture radar complex image quantization and decoding device can relatively losslessly maintain amplitude and phase information, ensure absolute radiation accuracy and the phase accuracy required for subsequent interference applications, is beneficial to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduces the error impact of quantization on power and phase.

[0185] In another optional embodiment, as Figure 2 shown, the first quantization module 202 calculates the SAR scattering response data set to obtain a basic data set, including:

[0186] S21, perform a modulus operation on the SAR scattering response data set to obtain the maximum amplitude dB value of the SAR scattering response and the minimum amplitude dB value of the SAR scattering response;

[0187] S22, perform an expansion calculation on the maximum amplitude dB value of the SAR scattering response to obtain the maximum amplitude threshold setting dB value;

[0188] S23, perform an expansion calculation on the minimum amplitude dB value of the SAR scattering response to obtain the minimum amplitude threshold setting dB value and the minimum amplitude threshold raw value;

[0189] S24, perform a weight calculation on the maximum amplitude threshold dB value and the minimum amplitude threshold dB value to obtain the quantization weight, and the calculation expression is:

[0190] Weight=(AmpMaxThres dB -AmpMinThresdB ) / X

[0191] X = 2 J-1 -1

[0192] where X is the quantization step size, J is the quantization bit number, Weight is the quantization weight, AmpMaxThres dB is the dB value of the maximum amplitude threshold setting, and AmpMinThres dB is the dB value of the minimum amplitude threshold setting.

[0193] It can be seen that implementing Figure 2 the described synthetic aperture radar complex image quantization and decoding device can calculate the weights for the maximum amplitude threshold dB value and the minimum amplitude threshold dB value to obtain the quantization weight, which is beneficial to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reducing the error effects of quantization on power and phase.

[0194] In another alternative embodiment, as Figure 2 shown, the first quantization module 202 performs a modulus operation on the SAR scattering response data set to obtain the maximum amplitude dB value and the minimum amplitude dB value of the SAR scattering response, including:

[0195] S211. Perform a point-by-point modulus operation on the SAR scattering response data set to obtain the amplitude value of the SAR scattering response. The calculation expression is:

[0196] Amp = sqrt(I 2 + Q 2 )

[0197] where I is the real part original value of the scattering response of any pixel point, Q is the imaginary part original value of the scattering response of any pixel point, sqrt(·) is the square root calculation, and Amp is the amplitude value of the SAR scattering response of any pixel point;

[0198] S212. Perform statistical analysis on the SAR scattering response amplitude values to obtain the maximum amplitude value and the minimum amplitude value of the SAR scattering response;

[0199] S213. Perform dB value conversion calculation on the maximum amplitude value and the minimum amplitude value of the SAR scattering response to obtain the maximum amplitude dB value and the minimum amplitude dB value of the SAR scattering response. The calculation expression is:

[0200] AmpMax dB = 20 * log 10 (AmpMax)

[0201] AmpMindB = 20 * log 10 (AmpMin)

[0202] Wherein, AmpMax is the maximum amplitude value of the SAR scattering response, AmpMin is the minimum amplitude value of the SAR scattering response, AmpMax dB is the maximum amplitude dB value of the SAR scattering response, AmpMin dB is the minimum amplitude dB value of the SAR scattering response, log 10 (·) is the logarithmic function with base 10.

[0203] It can be seen that implementing Figure 2 the described synthetic aperture radar complex image quantization and decoding device can perform statistical analysis on the SAR scattering response amplitude value, obtain the maximum amplitude value of the SAR scattering response and the minimum amplitude value of the SAR scattering response, which is more conducive to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduces the error impact of quantization on power and phase.

[0204] In another optional embodiment, as Figure 2 shown, the first quantization module 202 performs an expansion calculation on the maximum amplitude dB value of the SAR scattering response to obtain the maximum amplitude threshold setting dB value, including:

[0205] S221, preset the maximum amplitude protection band dB value; the maximum amplitude protection band dB value is an integer multiple of 10;

[0206] S222, round up the maximum amplitude dB value of the SAR scattering response to obtain the maximum amplitude rounded dB value;

[0207] S223, calculate the maximum amplitude protection band dB value and the maximum amplitude rounded dB value to obtain the maximum amplitude threshold setting dB value, and the calculation expression is:

[0208] AmpMaxThres dB = AmpMaxProTape dB + AmpMaxRound dB

[0209] Wherein, AmpMaxProTape dB is the maximum amplitude protection band dB value, AmpMaxRound dB is the maximum amplitude rounded dB value.

[0210] It can be seen that implementing Figure 2The described synthetic aperture radar complex image quantization and decoding device can round up the maximum amplitude dB value of the SAR scattering response to obtain the rounded maximum amplitude dB value, which is more conducive to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduces the error effects of quantization on power and phase.

[0211] In another optional embodiment, as Figure 2 shown, the first quantization module 202 performs an expansion calculation on the minimum amplitude dB value of the SAR scattering response to obtain the minimum amplitude threshold setting dB value and the minimum amplitude threshold original value, including:

[0212] S231, preset the minimum amplitude protection band dB value; the minimum amplitude protection band dB value is an integer multiple of 10;

[0213] S232, round down the minimum amplitude dB value of the SAR scattering response to obtain the rounded minimum amplitude dB value;

[0214] S233, calculate the minimum amplitude protection band dB value and the rounded minimum amplitude dB value to obtain the minimum amplitude threshold setting dB value, and the calculation expression is:

[0215] AmpMinThres dB =AmpMinProTape dB +AmpMinRound dB

[0216] In the formula, AmpMinProTape dB is the minimum amplitude protection band dB value, and AmpMinRound dB is the rounded minimum amplitude dB value;

[0217] S234, perform an original value reverse calculation on the minimum amplitude threshold setting dB value to obtain the minimum amplitude threshold original value, and the original value reverse calculation expression is:

[0218]

[0219] In the formula, AmpMinThres is the minimum amplitude threshold original value.

[0220] It can be seen that implementing Figure 2 the described synthetic aperture radar complex image quantization and decoding device can calculate the minimum amplitude protection band dB value and the rounded minimum amplitude dB value to obtain the minimum amplitude threshold setting dB value, which is more conducive to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduces the error effects of quantization on power and phase.

[0221] In another optional embodiment, as Figure 2As shown, the second quantization module 203 performs peak normalization uniform quantization calculation on the basis data set after logarithmic transformation to obtain the complex image quantization value of any pixel point, including:

[0222] S31, take the absolute value of the real part original value and the imaginary part original value of the scattering response of any pixel point respectively to obtain the real part absolute value and the imaginary part absolute value;

[0223] S32, add the minimum amplitude threshold original value to the real part absolute value and the imaginary part absolute value respectively, and perform dB value calculation to obtain the real part bias dB value and the imaginary part bias dB value. The calculation expressions are:

[0224] I bias =20*log 10 [abs(I)+AmpMinThres]

[0225] Q bias =20*log 10 [abs(Q)+AmpMinThres]

[0226] In the formula, I bias is the real part bias dB value, Q bias is the imaginary part bias dB value, abs(·) is the absolute value function;

[0227] S33, subtract the minimum amplitude threshold set dB value from the real part bias dB value and the imaginary part bias dB value of the scattering response respectively to obtain the real part updated dB value and the imaginary part updated dB value. The calculation expressions are:

[0228] I new =I bias -AmpMinThres dB

[0229] Q new =Q bias -AmpMinThres dB

[0230] In the formula, I new is the real part updated dB value, Q new is the imaginary part updated dB value;

[0231] S34, divide the real part updated dB value and the imaginary part updated dB value of the scattering response by the quantization weight respectively, and after integer calculation, multiply by the sign bits of the real part original value and the imaginary part original value of the scattering response respectively to obtain the real part quantization value of the complex image of this pixel point and the imaginary part quantization value of the complex image. The calculation expressions are:

[0232]

[0233]

[0234] Wherein, Weight is the quantization weight, and I Jbit is the quantization value of the real part of the complex image, and Q Jbit is the quantization value of the imaginary part of the complex image, round(·) is the rounding function, and sign(·) is the sign function.

[0235] It can be seen that implementing Figure 2 the described synthetic aperture radar complex image quantization and decoding device can perform peak normalization uniform quantization calculation on the basic data set after logarithmic transformation, which is beneficial to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reduces the error influence of quantization on power and phase.

[0236] In another optional embodiment, as Figure 2 shown, the decoding module 204 performs decoding calculation on the stored complex image quantization value to obtain the original complex image value of any pixel point, including:

[0237] S41, taking the absolute values of the quantization value of the real part of the stored complex image and the quantization value of the imaginary part of the complex image respectively to obtain the absolute value of the real part quantization and the absolute value of the imaginary part quantization;

[0238] S42, multiplying the absolute value of the real part quantization and the absolute value of the imaginary part quantization by the quantization weight respectively, and adding the minimum amplitude threshold setting dB value to obtain the real part bias dB value and the imaginary part bias dB value. The expressions are:

[0239] I bias = abs(I Jbit ) * Weight + AmpMinThres dB

[0240] Q bias = abs(Q Jbit ) * Weight + AmpMinThres dB

[0241] S43, performing power value calculation with base 10 on the real part bias dB value and the imaginary part bias dB value, then subtracting the original value of the minimum amplitude threshold from the power value, and multiplying by the sign bit of the real part quantization value and the sign bit of the imaginary part quantization value respectively to obtain the original value of the real part of the scattering response and the original value of the imaginary part of the scattering response. The expressions are:

[0242]

[0243]

[0244] Wherein, pow(10,·) is the exponential function with base 10.

[0245] It can be seen that by implementing Figure 2 the described synthetic aperture radar complex image quantization and decoding device, it is possible to perform decoding calculations on the stored complex image quantization values to obtain the original complex image values of any pixel point, which is more conducive to ensuring the stability of the quantization signal-to-noise ratio under different signal powers, and at the same time greatly reducing the error effects of quantization on power and phase.

[0246] Embodiment III

[0247] Please refer to Figure 3 , Figure 3 which is a schematic structural diagram of another synthetic aperture radar complex image quantization and decoding device disclosed in an embodiment of the present invention. Among them, Figure 3 the described device can be applied to a complex image quantization system, such as a local server or a cloud server for synthetic aperture radar complex image quantization and decoding management, etc., which is not limited in the embodiments of the present invention. As Figure 3 shown, the device may include:

[0248] a memory 301 storing executable program code;

[0249] a processor 302 coupled to the memory 301;

[0250] The processor 302 calls the executable program code stored in the memory 301 to execute the steps in the synthetic aperture radar complex image quantization and decoding method described in Embodiment I.

[0251] Embodiment IV

[0252] An embodiment of the present invention discloses a computer-readable storage medium that stores a computer program for electronic data exchange, wherein the computer program causes a computer to execute the steps in the synthetic aperture radar complex image quantization and decoding method described in Embodiment I.

[0253] Embodiment V

[0254] An embodiment of the present invention discloses a computer program product, which includes a non-transitory computer-readable storage medium storing a computer program, and the computer program is operable to cause a computer to execute the steps in the synthetic aperture radar complex image quantization and decoding method described in Embodiment I.

[0255] The device embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed to multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative work.

[0256] Through the above specific descriptions of the embodiments, those skilled in the art can clearly understand that each implementation can be achieved by means of software plus a necessary general hardware platform, and of course, it can also be achieved by hardware. Based on this understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, and the storage medium includes read-only memory (ROM), random access memory (RAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), one-time programmable read-only memory (OTPROM), electrically-erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc memories, magnetic disk memories, tape memories, or any other computer-readable medium capable of carrying or storing data.

[0257] Finally, it should be noted that: The synthetic aperture radar complex image quantization and decoding method and device disclosed in the embodiments of the present invention only disclose the preferred embodiments of the present invention, which are only used to illustrate the technical solutions of the present invention and are not intended to limit them; Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for quantifying and decoding synthetic aperture radar complex images, characterized in that, The method includes: S1. Obtain a SAR scattering response data set of a typical scenario under a SAR sensor and the original complex image value of any pixel to be quantized; the SAR scattering response data set includes SAR scattering response data of several typical scenarios; the original complex image value includes the original real part value of the scattering response and the original imaginary part value of the scattering response; S2. Calculate the SAR scattering response data set to obtain a basic data set; S3. Perform logarithmic transformation-based peak normalization uniform quantization calculation on the basic data set and the original complex image value of any pixel to be quantized to obtain the quantized complex image value of any pixel; the quantized complex image value includes the quantized real part value of the scattering response and the quantized imaginary part value of the scattering response; S4. Perform decoding calculation on the stored quantized complex image value of any pixel to obtain the original complex image value of any pixel; Wherein, calculating the SAR scattering response data set to obtain a basic data set includes: S21. Perform a modulus operation on the SAR scattering response data set to obtain the maximum amplitude dB value of the SAR scattering response and the minimum amplitude dB value of the SAR scattering response; S22. Perform expansion calculation on the maximum amplitude dB value of the SAR scattering response to obtain the set maximum amplitude threshold dB value; S23. Perform expansion calculation on the minimum amplitude dB value of the SAR scattering response to obtain the set minimum amplitude threshold dB value and the original minimum amplitude threshold value; S24. Perform weight calculation on the set maximum amplitude threshold dB value and the set minimum amplitude threshold dB value to obtain a quantization weight, and the calculation expression is: Weight=(AmpMaxThres dB -AmpMinThres dB ) / X X＝2 J-1 -1 where X is the quantization order, J is the quantization bit number, Weight is the quantization weight, AmpMaxThres dB is the dB value of the maximum amplitude threshold setting, AmpMinThres dB is the dB value of the minimum amplitude threshold setting; Wherein, performing logarithmic transformation-based peak normalization uniform quantization calculation on the basic data set and the original complex image value of any pixel to be quantized to obtain the quantized complex image value of any pixel includes: S31. Take the absolute value of the original real part value of the scattering response and the original imaginary part value of the scattering response of any pixel respectively to obtain the absolute value of the real part and the absolute value of the imaginary part; S32. Add the original minimum amplitude threshold value to the absolute value of the real part and the absolute value of the imaginary part respectively and perform dB value calculation to obtain the offset dB value of the real part and the offset dB value of the imaginary part, and the calculation expression is: I bias = 20*log 10 [abs(I) + AmpMinThres] Q bias = 20 * log 10 [abs(Q) + AmpMinThres] Wherein, I bias is the real part offset dB value, Q bias is the imaginary part offset dB value, and abs(·) is the absolute value function; S33. Subtract the set minimum amplitude threshold dB value from the offset dB value of the real part and the offset dB value of the imaginary part of the scattering response respectively to obtain the updated dB value of the real part and the updated dB value of the imaginary part, and the calculation expression is: I new = I bias - AmpMinThres dB Q new = Q bias - AmpMinThres dB where I new is the updated dB value of the real part, and Q new is the updated dB value of the imaginary part; S34. Divide the updated dB value of the real part and the updated dB value of the imaginary part of the scattering response by the quantization weight respectively, perform rounding calculation, and then multiply by the sign bits of the original real part value and the original imaginary part value of the scattering response respectively to obtain the quantized real part value of the complex image of this pixel and the quantized imaginary part value of the complex image, and the calculation expression is: Where Weight is the quantization weight, I Jbit is the quantization value of the real part of the complex image, Q Jbit is the quantization value of the imaginary part of the complex image, round(·) is the rounding function, and sign(·) is the sign function.

2. The synthetic aperture radar complex image quantization and decoding method according to claim 1, wherein Performing a modulus operation on the SAR scattering response data set to obtain the maximum amplitude dB value of the SAR scattering response and the minimum amplitude dB value of the SAR scattering response includes: S211. Perform a modulo operation on each point of the SAR scattering response data set to obtain the amplitude value of the SAR scattering response. The calculation expression is as follows: Amp=sqrt(I 2 +Q 2 ) In the formula, I is the original real part value of the scattering response of any pixel point, Q is the original imaginary part value of the scattering response of any pixel point, sqrt(·) is the square root calculation, and Amp is the amplitude value of the SAR scattering response of any pixel point; S212. Conduct statistical analysis on the SAR scattering response amplitude value to obtain the maximum amplitude value and the minimum amplitude value of the SAR scattering response; S213. Perform dB value conversion calculation on the maximum amplitude value and the minimum amplitude value of the SAR scattering response to obtain the maximum amplitude dB value and the minimum amplitude dB value of the SAR scattering response. The calculation expression is as follows: AmpMax dB = 20*log 10 (AmpMax) AmpMin dB = 20*log 10 (AmpMin) Wherein, AmpMax is the maximum amplitude value of the SAR scattering response, AmpMin is the minimum amplitude value of the SAR scattering response, AmpMax dB is the maximum amplitude dB value of the SAR scattering response, AmpMin dB is the minimum amplitude dB value of the SAR scattering response, log 10 (·) is the logarithmic function with base 10.

3. The synthetic aperture radar complex image quantization and decoding method according to claim 1, characterized in that The expansion calculation of the maximum amplitude dB value of the SAR scattering response to obtain the maximum amplitude threshold setting dB value includes: S221. Preset the maximum amplitude protection band dB value; the maximum amplitude protection band dB value is an integer multiple of 10; S222. Round up the maximum amplitude dB value of the SAR scattering response to obtain the maximum amplitude rounded dB value; S223. Calculate the maximum amplitude protection band dB value and the maximum amplitude rounded dB value to obtain the maximum amplitude threshold setting dB value. The calculation expression is as follows: AmpMaxThres dB = AmpMaxProTape dB + AmpMaxRound dB where AmpMaxProTape dB is the dB value of the maximum amplitude protection band, and AmpMaxRound dB is the rounded dB value of the maximum amplitude.

4. The synthetic aperture radar complex image quantization and decoding method according to claim 1, characterized in that The expansion calculation of the minimum amplitude dB value of the SAR scattering response to obtain the minimum amplitude threshold setting dB value and the original minimum amplitude threshold value includes: S231. Preset the minimum amplitude protection band dB value; the minimum amplitude protection band dB value is an integer multiple of 10; S232. Round down the minimum amplitude dB value of the SAR scattering response to obtain the minimum amplitude rounded dB value; S233. Calculate the minimum amplitude protection band dB value and the minimum amplitude rounded dB value to obtain the minimum amplitude threshold setting dB value. The calculation expression is as follows: AmpMinThres dB = AmpMinProTape dB + AmpMinRound dB where AmpMinProTape dB is the dB value of the minimum amplitude guard band, and AmpMinRound dB is the dB value of the minimum amplitude rounding; S234. Perform the reverse calculation of the original value on the minimum amplitude threshold setting dB value to obtain the original minimum amplitude threshold value. The reverse calculation expression of the original value is as follows: In the formula, AmpMinThres is the original minimum amplitude threshold value.

5. The synthetic aperture radar complex image quantization and decoding method according to claim 1, characterized in that, The decoding calculation of the complex image quantization value of any stored pixel point to obtain the original complex image value of any pixel point includes: S41. Take the absolute value of the real part quantization value and the imaginary part quantization value of the stored complex image respectively to obtain the real part quantization absolute value and the imaginary part quantization absolute value; S42. Multiply the real part quantization absolute value and the imaginary part quantization absolute value by the quantization weight respectively, and add the minimum amplitude threshold setting dB value to obtain the real part bias dB value and the imaginary part bias dB value. The expression is as follows: I bias = abs(I Jbit ) * Weight + AmpMinThres dB Q bias = abs(Q Jbit ) * Weight + AmpMinThres dB S43. Calculate the power value with base 10 for the real part offset dB value and the imaginary part offset dB value, then subtract the original minimum amplitude threshold value from the power value, and then multiply by the sign bit of the real part quantization value and the sign bit of the imaginary part quantization value respectively to obtain the original real part value and the original imaginary part value of the scattering response. The expression is as follows: In the formula, pow(10,·) is an exponential function with base 10.

6. A synthetic aperture radar complex image quantization and decoding device, characterized in that, The device includes: A memory storing executable program code; A processor coupled to the memory; The processor calls the executable program code stored in the memory and executes the synthetic aperture radar complex image quantization and decoding method according to any one of claims 1-5.

7. A computer storage medium, characterized in that, The computer storage medium stores computer instructions, which are used to execute the synthetic aperture radar complex image quantization and decoding method according to any one of claims 1-5 when the computer instructions are called.

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