Display calibration apparatus and method, and display control circuit and method

Abstract

The present invention discloses a display correction apparatus and method, as well as a display control circuit and method. The display control method is used to control a display, and includes: controlling the display to display a pattern; in response to a selection signal, selecting one of a plurality of luminance curves as a target luminance curve, or interpolating to generate the target luminance curve; and controlling the luminance of the display according to the target luminance curve.

Description

Technical Field

[0001] The present invention relates to a display, and more particularly to a display calibration device and method, as well as a display control circuit and method. Background Art

[0002] With the progress of technology, different from the previous way of observing medical images by using film and light box, nowadays most doctors or professionals use displays to observe medical images and extract information therefrom to judge whether the corresponding patient has symptoms. These medical images, including X-ray images, ultrasonic images, tomography images, etc., are mostly presented in grayscale, and the difference in pixel values on these images may represent specific symptoms. Since these differences are very subtle, the display must be calibrated with a specific brightness curve to make it easier for users to observe. If the brightness of the display is not correctly calibrated, it may lead to misjudgment or omission of symptoms by users.

[0003] Traditional calibration methods require an in-built or external illuminometer to measure the brightness of the display. However, because the ambient light intensity of the display is usually uneven, it is necessary to measure the brightness at multiple positions of the display, otherwise errors will occur. This step is not only time-consuming but also increases the hardware cost of calibration.

[0004] Traditional calibration methods also require prior knowledge of the accurate reflectivity of the display. However, because the reflectivity of the display is not easy to measure, this step is both complex and time-consuming. Summary of the Invention

[0005] In view of the deficiencies of the prior art, an object of the present invention is to provide a display calibration device and method, as well as a display control circuit and method, to improve the deficiencies of the prior art.

[0006] An embodiment of the present invention provides a display correction device, comprising a brightness measurement device, a memory, and a calculation circuit. The brightness measurement device is used to measure a first brightness and a second brightness of a display. The memory is used to store a plurality of program codes or program instructions. The calculation circuit is coupled to the brightness measurement device and the memory, and is used to execute the program codes or program instructions to perform the following steps: (A) determining a product range of an ambient light intensity and a reflectivity of the display; (B) determining a first product and a second product from the product range according to the product range, the first brightness, and the second brightness; (C) generating a first brightness curve based on the first brightness, the second brightness, and the first product; (D) generating a second brightness curve based on the first brightness, the second brightness, and the second product; (E) generating a third brightness curve corresponding to a third product based on the first brightness curve, the second brightness curve, the first product, and the second product, the third product being between the first product and the second product; and (F) determining whether the third brightness curve meets a target condition.

[0007] Another embodiment of the present invention provides a display correction method, comprising: (A) a brightness measurement device measures a first brightness and a second brightness of a display; (B) determining a product range of an ambient light intensity and a reflectivity of the display; (C) determining a first product and a second product from the product range according to the product range, the first brightness, and the second brightness; (D) generating a first brightness curve based on the first brightness, the second brightness, and the first product; (E) generating a second brightness curve based on the first brightness, the second brightness, and the second product; (F) generating a third brightness curve corresponding to a third product based on the first brightness curve, the second brightness curve, the first product, and the second product, the third product being between the first product and the second product; and (G) determining whether the third brightness curve meets a target condition.

[0008] Another embodiment of the present invention provides a display control circuit for controlling a display, comprising a memory and a calculation circuit. The memory is used to store a plurality of brightness curves and a plurality of program codes or program instructions. The calculation circuit is coupled to the memory and is used to execute the program codes or program instructions to perform the following steps: controlling the display to display a pattern; in response to a selection signal, selecting one of the brightness curves as a target brightness curve, or interpolating to generate the target brightness curve; and controlling the brightness of the display according to the target brightness curve.

[0009] Another embodiment of the present invention provides a display control method for controlling a display, comprising: controlling the display to display a pattern; in response to a selection signal, selecting one of a plurality of luminance curves as a target luminance curve, or interpolating to generate the target luminance curve; and controlling the luminance of the display according to the target luminance curve.

[0010] Regarding the features, implementation and technical effects of the present invention, detailed embodiments will be described below in conjunction with the accompanying drawings. Description of the Drawings

[0011] Figure 1 It is a functional block diagram of an embodiment of a display calibration device of the present invention;

[0012] Figure 2 It is a flowchart of an embodiment of a display calibration method of the present invention;

[0013] Figure 3 It is a functional block diagram of an embodiment of a display control circuit of the present invention; and

[0014] Figure 4 It is a flowchart of an embodiment of a display control method of the present invention.

[0015] Symbol Description

[0016] 100: Display calibration device

[0017] 105, 300: Display

[0018] 110: Luminance measurement device

[0019] 120, 312: Calculation circuit

[0020] 130, 314: Memory

[0021] 305: Display panel

[0022] 310: Display control circuit

[0023] S210, S220, S230, S240, S250, S260, S270, S280, S410, S420, S430, S440, S450, S460: Steps Detailed Embodiments

[0024] The technical terms in the following description are referred to the common terms in the technical field. If the present specification explains or defines some terms, the explanations of these terms shall be subject to the explanations or definitions in the present specification.

[0025] The disclosure of the present invention includes a display calibration device and method, as well as a display control circuit and method. Since some of the components included in the calibration device and control circuit of the present invention may be known components individually, details of the known components will be omitted in the following description without affecting the full disclosure and implementability of the device invention. In addition, part or all of the processes of the calibration method and control method of the present invention may be in the form of software and / or firmware, and may be executed separately by the calibration device and control circuit of the present invention or their equivalent devices. Without affecting the full disclosure and implementability of the method invention, the following description of the method invention will focus on the step content rather than the hardware.

[0026] Due to the poor observability of grayscale medical images, the display must be calibrated with a specific brightness curve so that users can more easily observe the symptoms contained in the medical images. Generally, the grayscale standard display function (GSDF) defined in the Digital Imaging and Communications in Medicine (hereinafter referred to as DICOM) is used as the method or standard for calibrating the brightness curve. The goal of the DICOM-defined brightness curve is to make the brightness difference corresponding to any two adjacent brightness codes of the display perceptible to the human eye, and the same brightness code difference of the display gives the same perception to the human eye. Each just-noticeable difference (JND) corresponding luminance is defined in the DICOM file, and the relationship between the just-noticeable difference and luminance can be transformed by the following equations (1) and (2).

[0027]

[0028] J(L) = A + B·log 10 (L) + C·(log 10 (L)) 2 + D·(log 10 (L)) 3 + E·(log 10 (L)) 4 + F·(log 10 (L)) 5 + G·(log 10 (L)) 6 + H·(log 10 (L)) 0 + I·(log 10 (L))8 (2)

[0029] Among them, L represents luminance (nits), j represents the just noticeable difference, Ln() represents the operation of the natural logarithm, a = -1.3011877, b = -2.5840191E-2, c = 8.0242636E-2, d = -1.0320229E-1, e = 1.3646699E-1, f = 2.8745620E-2, g = -2.5468404E-2, h = -3.1978977E-3, k = 1.2992634E-4, m = 1.3635334E-3.

[0030] During calibration, the brightness curve of the display is calibrated according to the first brightness, the second brightness of the display, and the intensity of the ambient light (such as illuminance), as shown in the following equations (3) to (7).

[0031] L′ min = L min + R d × L amb (3)

[0032] L′ max = L max + R d × L amb (4)

[0033] J min = J(L′ min ) (5)

[0034] J max = J(L′ max ) (6)

[0035]

[0036] Among them, L min represents the first brightness (nits), L max represents the second brightness (nits), R d represents the reflectivity of the display (nits / lux), L amb represents the ambient light intensity (lux), P i represents the brightness code value of the display brightness, and ΔP represents the difference between the maximum code value and the minimum code value. For example, if the specification of the display is 8 bits, then 0 ≤ P i ≤ 255, and ΔP = 255; if the specification of the display is 10 bits, then 0 ≤ P i ≤ 1023, and ΔP = 1023. In some embodiments, the first brightness L mincan be 95% or more of the maximum brightness of the display, while the second brightness L max can be 5% or less of the minimum brightness of the display, but not limited thereto.

[0037] It can be seen from equations (3) to (7) that during calibration, the first brightness L of the display is obtained first min and the second brightness L max , and the influence of the ambient light source on the display is considered (for example, the reflectance R d and the ambient light intensity L amb product R d ×L amb ) to calculate the third brightness L' min and the fourth brightness L' max (that is, equations (3) and (4)). Then, the third brightness L' min is converted into the first just noticeable difference J min (that is, equation (5)) by using equation (2) or by looking up a table, and the fourth brightness L' max is converted into the second just noticeable difference J max (that is, equation (6)). After obtaining the first just noticeable difference J min and the second just noticeable difference J max , the just noticeable difference corresponding to each brightness code value of the display can be deduced (that is, equation (7)). Then, the just noticeable difference is converted back to brightness (that is, equation (1)), and in this way, the brightness corresponding to each brightness code value of the display can be obtained, which is the process of the calibrated brightness curve.

[0038] Two documents, TG-18 and TG-270, of the American Association of Physicists in Medicine (AAPM) and the document 62563-1 of the International Electrotechnical Commission (IEC) define the specifications that medical displays should have, using the ratio (dL / L) of the brightness difference to the brightness of each just noticeable difference error (JND error) as the main reference value, as shown in equations (8) to (10).

[0039]

[0040]

[0041]

[0042] δ i corresponds to 0.5(J i -Ji-1 ) the measured value of "the ratio of the luminance difference per just noticeable difference to the luminance", corresponds to 0.5 (J i -J i-1 ) the theoretical value of "the ratio of the luminance difference per just noticeable difference to the luminance", k δ is "the ratio of the luminance difference per just noticeable difference error to the luminance".

[0043] When calculating k δ , generally only the luminance at a specific luminance code value will be measured. Taking TG-18 as an example, if the monitor is of 8-bit specification (luminance code value ranges from 0 to 255), the luminance will be measured every 15 luminance code values, and a total of 18 luminance code values will be measured, and the measured value will be used to calculate δ i (Equation (8)), and compared with (Equation (9)) to obtain k δ (Equation (10)).

[0044] It can be seen from Equation (3) to Equation (7) that affected by the ambient light source (for example, the ambient light intensity L amb changes), the luminance curve of the monitor will change. If the current luminance curve is not changed along with the ambient light source, it may cause "the ratio of the luminance difference per just noticeable difference error to the luminance" to exceed the standard. Therefore, it is necessary to correct the luminance curve according to the change of the ambient light source.

[0045] Figure 1 is a functional block diagram of an embodiment of the monitor correction device of the present invention, Figure 2 is a flowchart of an embodiment of the monitor correction method of the present invention. The monitor correction device 100 includes a luminance measurement device 110, a calculation circuit 120, and a memory 130. The monitor correction method includes the following steps.

[0046] Step S210: The luminance measurement device 110 measures the first luminance L of the monitor 105 min and the second luminance L max . The luminance measurement device 110 can be implemented with an existing luminance meter.

[0047] Step S220: The calculation circuit 120 determines the product range of the ambient light intensity L amb and the reflectivity R of the monitor 105 d (that is, determines the range of L amb ×R d ). For example, when obtaining the possible range of the reflectivity R d (for example: 0.01 > R d > 0.001) and the ambient light intensity L ambPossible range (e.g., 100 > L amb > 0.5), then the calculation circuit 120 can calculate R d ×L amb Possible range (e.g., 1 > R d ×L amb > 0.0005). In some embodiments, the reflectance R d Possible range is obtained from the specification of the display 105 or estimated according to the material of the surface of the display 105, and the ambient light intensity L amb Possible range is estimated based on the possible usage environment of the display 105.

[0048] Step S230: The calculation circuit 120 determines a first product A0 and a second product A1 from the range of L min ×R max and L amb ×R d based on the ranges of the first luminance L amb ×R d . That is, the first product A0 and the second product A1 are between the maximum value of L amb ×R d and the minimum value of L amb ×R d .

[0049] Step S240: The calculation circuit 120 generates a first luminance curve G0 corresponding to the first product A0 based on the first luminance L min and the second luminance L max . More specifically, the calculation circuit 120 obtains the first luminance curve G0 based on equations (1) to (7) in this step.

[0050] Step S250: The calculation circuit 120 generates a second luminance curve G1 corresponding to the second product A1 based on the first luminance L min and the second luminance L max . More specifically, the calculation circuit 120 obtains the second luminance curve G1 based on equations (1) to (7) in this step.

[0051] Step S260: The calculation circuit 120 generates a third luminance curve g0 corresponding to a third product a0 based on the first luminance curve G0, the second luminance curve G1, the first product A0, and the second product A1, where the third product a0 is between the first product A0 and the second product A1. In some embodiments, the calculation circuit 120 obtains the third luminance curve g0 based on interpolation.

[0052] Step S270: The calculation circuit 120 determines whether the third luminance curve g0 meets the target condition. In some embodiments, the target condition may be the conditions specified or regulated in documents such as TG 18, TG 270, and / or IEC 62563-1 for k δ (i.e., "the ratio of the luminance difference corresponding to each just-noticeable difference error to the luminance"). For example, the target condition may be that k δ is less than or equal to a threshold value (e.g., k δ ≤10%). If the third luminance curve g0 meets the target condition, the calculation circuit 120 executes step S280; if the third luminance curve g0 does not meet the target condition, the calculation circuit 120 executes step S230. The result of step S270 being No indicates that the first product A0 and / or the second product A1 are not ideal, so the calculation circuit 120 executes step S230 again to re-determine the first product A'0 (different from the first product A0) and / or re-determine the second product A'1 (different from the second product A1).

[0053] Step S280: The calculation circuit 120 establishes the correspondence between the first product A0 and the first luminance curve G0, and establishes the correspondence between the second product A1 and the second luminance curve G1. In some embodiments, the calculation circuit 120 establishes a look-up table in the memory 130 to record the correspondence between the product and the luminance curve.

[0054] In other embodiments, the calculation circuit 120 may determine more than three products (A0 to A n , where n is an integer greater than or equal to 2) (extension of step S230), generate multiple luminance curves (G0 to G n ) corresponding to these products (A0 to A n ) (extensions of steps S240 and S250), interpolate to generate multiple luminance curves (g0 to g k and A k+1 , 0 ≤ k ≤ n - 1) (extension of step S260), determine whether these interpolated luminance curves (g0 to g m ) meet the target condition (extension of step S270), and when these interpolated luminance curves (g0 to g m ) meet the target condition, establish the correspondence between these products (A0 to A m ) and these luminance curves (G0 to G n ) (extension of step S280). n ) (extensions of steps S280). After the process of

[0055] Figure 2 ends, multiple luminance curves (G0 to G n ​) and its corresponding reflectance R d The product (A0 to A amb ) with the ambient light intensity L n These data can be used to control, correct, or set the display.

[0056] Figure 3 FIG. 10 is a functional block diagram of an embodiment of the display control circuit of the present invention. Figure 4 FIG. 11 is a flowchart of an embodiment of the display control method of the present invention. The display 300 includes a display panel 305 and a display control circuit 310. The display control circuit 310 includes a calculation circuit 312 and a memory 314. The display 300 can be a general display or a medical display. The display control circuit 310 is used to control the display panel 305 to display an image. For example, the display control circuit 310 is a scaler of the display 300. In addition to controlling the on-screen display (OSD) of the display 300, it can also process the image signal input to the display 300 (including but not limited to image scaling, deinterlacing, color adjustment, brightness (gray scale) adjustment), and then control the display panel 305 to display the processed image. The memory 314 can include a non-volatile memory (such as a flash memory) and a volatile memory (such as a dynamic random access memory). The image signal can be generated by a computer or a medical device coupled to the display 300. The memory 314 stores a plurality of program codes or program instructions, and the calculation circuit 312 executes these program codes or program instructions to implement the functions of the display control circuit 310. In some embodiments, the memory 314 also stores a first brightness L min , a second brightness L max , a plurality of brightness curves (G0 to G n ) and their corresponding reflectance R d The product (A0 to A amb ) with the ambient light intensity L n ) of one or more of them. The display control method includes the following steps.

[0057] Step S410: The display control circuit 310 controls the display 300 to display a pattern. The pattern can be the "Quality Control" gray scale pattern (such as "TG18-QC") specified by TG-18, which is used for the user to judge whether the details displayed on the display panel 305 can be clearly recognized. In some embodiments, the pattern is stored in the memory 314, and the calculation circuit 312 displays the pattern in the form of an on-screen display. In other embodiments, the pattern is input to the display 300 through an image signal.

[0058] Step S420: The display control circuit 310 receives a selection signal and searches for a brightness curve according to the selection signal. The selection signal corresponds to the product of the reflectivity R d and the ambient light intensity L amb . The selection signal can be triggered by a screen on the display 300 (for example, the display panel 305 is a touch panel) or a button, or generated by a device coupled to the display 300 (i.e., the user operates the device to generate the selection signal). The calculation circuit 312 searches for the corresponding brightness curve in the memory 314 according to the selection signal.

[0059] Step S430: The calculation circuit 312 determines whether a brightness curve corresponding to the selection signal can be found in the memory 314. If the result of step S430 is yes, the display control circuit 310 executes step S440; otherwise, the display control circuit 310 executes step S450.

[0060] Step S440: The calculation circuit 312 uses the brightness curve corresponding to the selection signal as the target brightness curve. More specifically, the display control circuit 310 finds the brightness curve (for example, G k ) corresponding to the selection signal (for example, A k ) in the memory 314 in step S420. Therefore, the display control circuit 310 uses the found brightness curve (for example, G k ) as the target brightness curve.

[0061] Step S450: The calculation circuit 312 generates the target brightness curve by interpolation. More specifically, when the memory 314 does not store the brightness curve corresponding to the selection signal (for example, a k , A k <a k <A k+1 ), the calculation circuit 312 performs interpolation calculation according to the selection signal and the multiple brightness curves (for example, G k and G k+1 ) stored in the memory 314 and their corresponding products (A k and A k+1 ) to generate the target brightness curve. It should be understood that the interpolation calculation is only a possible implementation manner and is not used to limit the present invention.

[0062] Step S460: The display control circuit 310 controls the brightness of the display 300 according to the target brightness curve. More specifically, the display control circuit 310 displays the video signal on the display panel 305 according to the target brightness. In other words, the brightness of each pixel of the display panel 305 can be controlled by the display control circuit 310 based on the target brightness curve.

[0063] In summary, since the calibration device, control circuit, and corresponding method of the present invention take into account both the ambient light intensity and the reflectivity of the display simultaneously (i.e., considering the two together as a single parameter (i.e., the above-mentioned product)), the user only needs to adjust one parameter (i.e., by selecting a signal or a product) to adjust the display to be suitable for the current usage scenario (e.g., the user can clearly distinguish the details on the "quality control" grayscale pattern), without the need for a complex or time-consuming calibration process. In addition, by using the interpolation method and verifying whether the interpolated luminance curve meets the target conditions, the present invention can support continuous adjustment (i.e., the value of the selection signal is continuous), and the finally selected target luminance curve can meet the requirements of calibration. Furthermore, since the ambient light intensity has been taken into account when generating multiple luminance curves (G0 to G n ) (i.e., the process of Figure 2 ), the user does not need to use a device other than the display (such as an illuminance meter) when performing the process of Figure 4 . Therefore, compared with the prior art, the present invention provides a calibration device, control circuit, and corresponding method with simple operation and time saving.

[0064] The calculation circuit 120 and the calculation circuit 312 can be circuits or electronic components with program execution capabilities, such as a central processing unit, a microprocessor, a microcontroller, a microprocessing unit, or their equivalent circuits. The calculation circuit 120 and the calculation circuit 312 respectively execute the processes of Figure 2 and Figure 4 by executing the program codes or program instructions stored in the memory 130 and the memory 314 respectively. In other embodiments, those skilled in the art of the present technology field can design the calculation circuit 120 and the calculation circuit 312 according to the above disclosure. That is to say, the calculation circuit 120 and the calculation circuit 312 can be an application specific integrated circuit (ASIC) or implemented by circuits or hardware such as a programmable logic device (PLD).

[0065] Since those skilled in the art of the present technology field can understand the implementation details and variations of the method invention of the present disclosure through the disclosure of the device invention of the present disclosure, therefore, to avoid redundancy, repeated descriptions are omitted herein on the premise of not affecting the disclosure requirements and implementability of the method invention. Please note that in the previous several drawings, the shapes, sizes, and proportions of the elements are only for illustration, for those skilled in the art of the present technology field to understand the present invention, and are not used to limit the present invention. In addition, in some embodiments, the order of the steps mentioned in the foregoing flowcharts can be adjusted according to actual operations, and even can be executed simultaneously or partially simultaneously.

[0066] Although the embodiments of the present invention are as described above, these embodiments are not intended to limit the present invention. Those skilled in the art of the present technology may make changes to the technical features of the present invention based on the explicit or implicit content of the present invention. All such changes may fall within the scope of patent protection sought by the present invention. In other words, the scope of patent protection of the present invention shall be subject to what is defined by the claims in this specification.

Claims

1. A display calibration device, comprising: A brightness measurement device for measuring a first brightness and a second brightness of a display; A memory for storing a plurality of program codes or program instructions; A calculation circuit, coupled to the brightness measurement device and the memory, for executing the plurality of program codes or program instructions to perform the following steps: (A) Determining a product range of an ambient light intensity and a reflectivity of the display; (B) Determining a first product and a second product from the product range according to the product range, the first brightness, and the second brightness; (C) Generating a first brightness curve based on the first brightness, the second brightness, and the first product; (D) Generate a second luminance curve based on the first luminance, the second luminance, and the second product; (E) Generate a third luminance curve corresponding to a third product based on the first luminance curve, the second luminance curve, the first product, and the second product, where the third product is between the first product and the second product; and (F) Determine whether the third luminance curve meets a target condition, wherein when the third luminance curve meets the target condition, the first luminance curve and the second luminance curve are used to calibrate the display.

2. The display calibration device according to claim 1, wherein when the third brightness curve does not meet the target condition, the calculation circuit executes steps (B) to (F) again.

3. The display calibration device according to claim 1, wherein when the third brightness curve meets the target condition, the calculation circuit further performs the following steps: (G) Establishing a correspondence between the first product and the first brightness curve and establishing a correspondence between the second product and the second brightness curve.

4. The display calibration device according to claim 1, wherein the target condition means that the ratio of the brightness difference per just noticeable difference error to the brightness is less than or equal to a threshold value.

5. A display calibration method, comprising: (A) A brightness measurement device measures a first brightness and a second brightness of a display; (B) Determining a product range of an ambient light intensity and a reflectivity of the display; (C) Determining a first product and a second product from the product range according to the product range, the first brightness, and the second brightness; (D) Generating a first brightness curve based on the first brightness, the second brightness, and the first product; (E) Generating a second brightness curve based on the first brightness, the second brightness, and the second product; (F) Generate a third luminance curve corresponding to a third product based on the first luminance curve, the second luminance curve, the first product, and the second product, where the third product is between the first product and the second product; and (G) Determine whether the third luminance curve meets a target condition, wherein, When the third luminance curve meets the target condition, the first luminance curve and the second luminance curve are used to calibrate the display.

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