43 results about "Jpeg image compression" patented technology

The invention relates to a method for detecting and positioning hidden information in a digital image, which comprises the following steps: detecting a digital image containing hidden information by using a blocking effect computing method; if the digital image is in a JPEG image compressed format, extracting a quantization matrix of the JPEG; deducing a quantization DCT coefficient of an original image before the embedment of the hidden information according to a DCT coefficient of the digital image; and restoring the pixel value of the original image according to the DCT coefficient of the original image, determining the embedment position of the hidden information according to the difference between the pixel values of the original image and the digital image, and estimating the embedding quantity of the hidden information. The technical proposal of the invention overcomes the drawback that the prior hidden information detection technology cannot accurately position the embedment position of the hidden information, and can detect and position hidden information hidden by various steganography algorithms in the digital image.

The invention discloses a cutting-resistant JPEG image compression history and synthetic tamper detection method. The method comprises the following steps: (1) calculating compression history trace and cutting position of an image to be detected; (2) determining whether the image to be detected has a tampered operation or not; (3) carrying out tamper area positioning on the image determined in the step (2), respectively figuring out difference images to RGB image three channels according to the mode of the step (2), carrying out binary processing on the difference images, carrying out logic and operation on the obtained three channel binary images to obtain a new binary image, carrying out morphological corrosion expansion operation on the image, and mapping back to the image to be measured to obtain a tampered area positioning image. According to the invention, problem is solved that block position of a JPEG image may be destroyed after cutting, which leads to sectional or complete failure of the prior art. Also effective detection and tampered area positioning on an image with cutting background area can be carried out by the method provided in the invention.

The invention provides a cramping method based on sampling technology under a transform domain. Internal smooth image areas are coded by utilizing sampling method under the transform domain and rebuilt with interpolation technology to substantially lower the coding bit rate. The image areas with complex internal patterns are coded with a conventional coding method based on JPEG cramping standard. The two coding methods are combined, and different coding strategies are employed for image areas of different types to realize highly efficient cramping of entire image signals. Compared with a conventional JPEG cramping method, the cramping method is highly flexible and efficient, and overcomes the defects of monotonous coding mode in conventional JPEG cramping method and low integral coding efficiency.

This invention puts forward a digital watermark method for protecting copyright information of digital multimedia products and content integrality at the same time, which embeds a Rodust watermark and a weak watermark in a multimedia product simultaneously to pick up the copyright information of the multimedia by testing the Rodust watermark and judge if the multimedia is trusted or juggled viciously by testing the weak watermark, which can protect the copyright to Jpeg image compression and image juggle operation and provides juggle prompt.

The invention discloses a runtime reconfigurable embedded security real-time image compression system and a runtime reconfigurable embedded security real-time image compression method. An image acquisition module is used for acquiring an original image, and temporarily storing the image. The data processing module acquires original image data from the image acquisition module, compresses and codes the original image data, and controls the output of a compressed code stream to a wireless communication module. The wireless communication module is used for the transmission and reception of the data. A power supply module is used for supplying required power to each corresponding module. An advanced RISC machine is taken as a core control unit, and is used for communicating with an upper computer, receiving an encrypted partial-reconfigurable configuration file from the upper computer and transmitting the compressed image data to the upper computer. In a management reconfiguration process, the partial-reconfigurable configuration file is decrypted, and the reconfiguration of a field programmable gate array (FPGA) is controlled. The FPGA serves as a joint photographic experts group (JPEG) image compression accelerator and accelerates an image compression process by parallel processing and pipelining technologies, and a quantification module and a Huffman coding module are dynamically changed by a runtime reconfigurable technology, so that security is enhanced.

The invention provides a high-efficiency image compression method based on a spatial domain downsampling mode. Through an image macro block, the interior of which is relatively smooth, the method based on the spatial domain downsampling is used for coding, and the interpolation technology is used for reconstruction, thereby greatly reducing the coding rate under the condition of guaranteeing the coding fidelity. Meanwhile, for an image macro block, the internal texture of which is relatively complex, a conventional coding method based on a JPEG image compression standard is employed for guaranteeing the high-efficiency coding of the image macro block. A conventional image compression method neglects the characteristic differences among different regions in an image, so the conventional image compression method cannot effectively remove correlation among pixel points, and causes the low overall coding efficiency. The method achieves the implementation of different coding strategies for the image macro block with different characteristics in a segmented manner, and achieves the high-efficiency coding of the whole image.

The invention provides a low-bit-rate image compression method based on intelligent quantization technology. On the premise of low-bit-rate compression, the coding is carried out by means of the intelligent quantization technology for the internally smoothing image blocks, and the reconstruction is carried out through the combination with the interpolation technology, on the premise of controlling the coding distortion, the coding rate is effectively reduced; and meanwhile, for the image blocks having complex internal textures, a conventional coding method based on the JPEG image compression standard is adopted to guarantee the efficient coding of the image blocks. The efficient coding of the whole image can be realized by adaptively selecting different coding strategies for image blocks with different texture features. Compared with a conventional JPEG image compression method, the low-bit-rate image compression method can overcome the defect of single coding mode in the conventional JPEG image compression method.

The invention provides a novel color image coding method. The method is characterized by, according to the characteristic that a transfer matrix between RGB and YCbCr color space is a non-unitary matrix, that is, unequivalence of error between RGB images and YCbCr images, with minimization of interpolation error of an RGB space being an objective, carrying out combined optimized filtering on three components of Y, Cb and Cr, after filtering, the resolution of the component Y keeping unchanged, and the resolutions of the two components Cb and Cr being reduced; after finishing filtering, carrying out compression on the three components through a standard JPEG image compression method; and carrying out coding on the RGB images based on the above, so that coding efficiency is improved greatly. The method can improve coding efficiency of the RGB color images, is not high in complexity and is easy to realize.

The invention provides a method which combines the surface fitting with a JPEG lossy compression coding technology, applies the technology combining the surface fitting with the JPEG image compression to compression of topographic data in a topographic database and a topographic matching database for real-time route planning and provides an airborne digital topographic data compression method for low altitude penetration. Firstly, surface fitting is performed on small blocks of topographic data after the large-scale topographic data is divided into small blocks of data on the basis of Marquardt, topographic data before fitting is compared with the topographic data after fitting, the residual is calculated and JPEG lossy compression is performed on the residual exceeding safe flying range (-100 m to 100 m) of a plane. The method not only retains the change of the topography, but also reduces the storage space of altitude data of the topography.

The invention belongs to the technical field of image processing and discloses a high-speed JPEG image compression method based on the TMS320C6678 chip. The method comprises the following steps: reading a to-be-compressed image; continuously dividing the data of the to-be-compressed image into 8 segments of data blocks along the distance direction in a non overlapping manner, scanning the respective data blocks by the 8 processing cores of the TMS320C6678 chip at the same time to accomplish image blocking; performing DCT transformation on the blocks; determining correction quantization tables corresponding to the blocks, and quantifying the blocks by using the correction quantization tables; performing Huffman entropy encoding on the quantized blocks; and determining marking code according to the JPEG standard and the format of the to-be-compressed image, and forming bit streams through the marking codes and the encoded data of the blocks. By adoption of the high-speed JPEG image compression method, the data redundancy can be reduced, the processing time of image compression can be shortened, and high-speed JPEG image real-time compression is realized.

The invention discloses a method for detecting human skin color region in JPEG image compression domain, comprising the steps of: initializing system parameters; performing Huffman decoding and inverse quantization on a to-be-detected JPEG image to obtain DCT coefficients corresponding to all image blocks on Y, Cb and Cr components; calculating color and texture characteristics of each image block; calculating skin color probability of each image block; according to the skin probabilities and texture characteristics, judging if each image block is a human skin color region. The advantages of the invention: it need not completely decompress an image but directly operates on a compressed code flow, speeding up the human skin color detection and improving detecting accuracy.

The invention discloses a JPEG image compression method based on polygon clipping DCT, which includes reading original uncompressed images, transforming the images into luminance and chromatic aberration images, and dividing the luminance and chromatic aberration images into 8-line and 8-column image blocks; utilizing the method combining Arai Agui Nakajima (AAN) fast DCT algorithm with polygon clipping DCT, and performing calculation based on clipping coefficients to obtain DCT coefficients of the 8-line and 8-column image blocks; and quantizing and encoding the DCT coefficients respectively based on an AAN quantization table and a JPEG standard encoding table to obtain JPEG compression image data. According to the JPEG image compression method based on polygon clipping DCT, complete DCT transformation of 8-line and 8-column image blocks is not needed, instead, the calculating number of the DCT coefficients is adjusted flexibly according to the clipping coefficients, and the polygon clipping DCT is effectively combined with the AAN fast DCT algorithm, so that DCT, the calculated amount of image compression quality during the quantitative phase is greatly reduced in the condition that application filed requirements are satisfied.

The invention discloses a maneuvering photoelectric detection and identification system for low, slow and small targets, which comprises an optical detection subsystem, a photoelectric parallel processing and identification subsystem and a servo subsystem, and is characterized in that the optical detection subsystem and the photoelectric parallel processing and identification subsystem are erected on the servo subsystem, and the servo subsystem is carried on a mounting platform of a carrier vehicle, the optical detection subsystem is used for collecting multiband optical information from a target and a background; the photoelectric parallel processing identification subsystem comprises a multiband image co-processing module and an information processing master control module, and each band co-processing module is used for carrying out single-frame detection identification on a target according to the image information of the corresponding band; the information processing master control module is used for performing multi-frame detection and identification on a target by adopting a JPEG image compression mode and a track association and multi-frame fusion mode; and the servo subsystem is used for completing target tracking according to the multi-frame detection identification result. The method is high in detection and recognition accuracy, high in maneuverability and capable of performing long-distance detection on a target.

The invention discloses a CWT-QIM digital blind watermarking algorithm, which includes the embedding process and the extracting process of watermark. The embedding process of watermark includes the generation of watermark image, selection of an embedded area, DCT transform and vector quantization modulation-based embedding; the watermark extraction process is basically the inverse operation of thewatermark embedding process; the algorithm of the invention has excellent robustness and transparency, can effectively resist JPEG image compression, Gaussian noise, median filter, salt and pepper noise, scaling, rotation, cropping and other image attacks, improve the performance of digital watermarking algorithm, quantization and embedding watermark information, and can be extracted blindly without the original carrier image, can be easily and effectively applied to digital content authentication or digital copyright protection and other fields.

The invention discloses a JPEG image compression artifact elimination algorithm based on a cascade residual error coding and decoding network CRED-Net, which comprises the following steps of: firstly,providing QF value estimation of a compressed image by using a quality factor (QF) prediction network, and then removing an appropriate cascade of artifacts of the compressed image by selecting an appropriate QF value for the estimated QF value. According to the method provided by the invention, multi-scale feature learning is carried out in a pixel domain, a discrete cosine transform (DCT) domain and a discrete wavelet transform (DWT) domain without depending on compressed encoding information of the JPEG image, and when the QF value of the image is not within the consideration range of a trained CREDNet model, a correction network is introduced to further correct the restored image. Experimental results prove that compared with other methods. The method provided by the invention can obtain better performance in a wider compression level range.

The invention relates to artificial intelligence and image compression technologies, and discloses an image processing method used for image compression and decompression. The method provided by the embodiment of the invention comprises the following steps: performing Huffman decoding on first JPEG image data to obtain a quantization coefficient; performing entropy estimation on the quantization coefficient to obtain an entropy estimation result, wherein the entropy estimation result is used for carrying out probability estimation on the quantization coefficient; and performing arithmetic coding on the quantization coefficient and the entropy estimation result to obtain first compressed data, wherein the storage space occupied by the first compressed data is smaller than the storage space occupied by the first JPEG image data. In the embodiment of the invention, after the first JPEG image data is subjected to Huffman decoding to obtain the quantization coefficient, the first compressed data is obtained, and in the process, the first JPEG image data does not need to be converted into an RGB image for entropy estimation, so that irrelevant information is reduced, and the JPEG image compression performance is improved.

This invention optimizes the entropy encoding part of JPEG (Joint Photographic Experts Group) image compression by modifying the run length encoding method that performs the actual compression by removing the redundancy from transformed and quantized image data. Using the fact that the preceding processes of run length coding, in JPEG compression algorithm, produces a large number of zeros, the original run length coding uses an ordered pair (a,b), where ‘a’ is the length of consecutive zeros preceding the ASCII character ‘b’. The proposed run length encoding scheme removes an unintended redundancy, from the original run length encoding scheme, by using an ordered pair only when a zero occurs and using the same EOB (End of Block) parameter at the end of each block. The proposed encoding scheme does not alter the value of PSNR but is found to be very effective in reducing the size of JPEG compressed image data.

The invention discloses a JPEG image decompression effect method based on DCT coefficient prediction. The method comprises the following steps: giving a compressed image, and sequentially extracting overlapped image blocks from the top left corner of the image through convolution operation of a network; performing DCT on each image block through a convolutional neural network to obtain a corresponding DCT coefficient; learning a nonlinear mapping relationship of the DCT coefficients by using a wide activation residual network; correcting the DCT coefficient learned through the network throughquantization constraint prior; carrying out IDCT transformation on the learned DCT coefficient by using a network, and transforming the learned DCT coefficient back to a pixel domain; the output of the network is recombined into an image by an inverse operation of the image block extraction operation. According to the JPEG image decompression effect method, the compression effect of the JPEG imagecan be effectively removed, and part of image detail information lost due to compression can be recovered. Therefore, the JPEG image compression effect removing method is an effective JPEG image compression effect removing method.

A received JPEG image compression format image includes one or more minimum coded units (MCUs). Each MCU is decoded using an image compression format decoder. Each decoded MCU is then split into multiple decoded subblocks. Each decoded subblock can then be encoded into texture compression format using a texture compression format encoder. Each encoded texture compression format subblock can then be passed to a graphical processing unit (GPU) for processing.

An image compression method disclosed by the present invention comprises the steps of separately evaluating the image quality of n compressed images obtained by separately adopting n sets of different quality factors to carry out the joint photographic experts group (JPEG) image compression on an original image, and obtaining n sets of quality evaluation scores; utilizing the n sets of quality evaluation scores and the corresponding quality factors to carry out the function fitting to obtain a function relation between the quality evaluation scores and the quality factors; utilizing the function relation between the quality evaluation scores and the quality factors to calculate a target quality factor corresponding to a target quality score; determining an optimal quality factor according to the target quality factor, and utilizing the optimal quality factor to carry out the JPEG image compression on the original image again. According to the present invention, the images can be compressed based on the low-calculation complexity and objective image quality evaluation, and the visual perception experiences of the users to the images can be guaranteed while an image compression rate is improved. The present invention also discloses an image compression device.

The invention discloses a JPEG (Joint Photographic Experts Group) image compression artifact elimination method based on a controllable pyramid wavelet network, which comprises the following steps of: firstly, extracting an image feature related to a compression level, secondly, guiding to recover a Y channel image by using the feature, and then guiding to recover a CbCr channel image by using the feature and the recovered Y channel image, and finally, converting the image into an RGB space to obtain a final recovery result. According to the method provided by the invention, image coding parameter information does not need to be predicted, a good recovery effect can be achieved for a plurality of images with different compression levels, each recovery network only needs to train a single network model, on one hand, the model uses jump connection to avoid the problems of gradient disappearance and gradient explosion possibly occurring in the training process, and on the other hand, model complexity is reduced by using a recursion module sharing parameter strategy, and efficient operation of the algorithm is ensured. Therefore, the method provided by the invention has the advantages of simple model, few parameters, wide application range, remarkable recovery effect and the like.

The invention provides a method for image compression based on a dual encoding mode. According to characteristics of different areas in an image, an efficient compression method is adaptively selected from a conventional JPEG image compression method and a conventional image compression method based on an intelligent quantization algorithm to compress each image macroblock through a rate-distortion optimization policy, so that the whole image is compressed efficiently, and different compression effects can be achieved for the areas having different contents in the image. Compared with the conventional JPEG image compression method, according to the method for image compression, the policy of adaptively selecting the efficient compression method according to the characteristics in the image is achieved, and the most efficient compression method can be provided for the different image areas.

The invention discloses a Color JPEG image format-compliant encryption and decryption method, comprising the following steps of: S1: determining the scale LT of a block T to be extracted; S2: selecting a ROI block from the compressed data segment of the original JPEG image, re-selecting the ROI block or supplementing a random block to the ROI block according to the relationship between the ROI block and the T size to make the ROI block equal to the T scale; S3: performing RC4 encryption on the block obtained in S2 to form an encrypted block; S4: scrambling and rearranging the remaining blocksin the compressed data segment of the original JPEG image; S5: reorganizing the block generated in S3 and the block scrambled and rearranged in S4 into a format-compliant encrypted JPEG image; S6: performing image restoration or image decryption. The compliant encrypted image block information according to the Color JPEG image format-compliant encryption and decryption method also changes the structure of the original image to make the encrypted image difficult to recognize. The method improves the validity and reliability of the algorithm, provides protection for the ROI, adapts to differentapplication scenarios, and retains the capability of performing certain detection and processing on the encrypted JPEG image, and can provide assistance for applications such as a cloud monitoring system and a cloud storage system.

The invention discloses a texture synthesis-based robust steganographic method. The method comprises the steps of firstly, capturing a certain quantity of candidate blocks from a source texture image to embed secret information; secondly, according to a key, drawing the candidate blocks in a blank canvas; and finally, selecting the proper candidate blocks to synthesize a texture image, and constructing a texture image with a relatively good visual effect. At a receiving end, a receiver determines the positions of the candidate blocks on the canvas according to the key, and the original secret information is extracted according to the complexity of the candidate blocks. The steganographic texture image synthesized with the method well reserves the style of the original texture image; the size of the texture image can be proportionally adjusted according to the capacity of the embedded information so as to realize high embedding rate; and due to the complexity of texture blocks, the secret information contained in the texture image is slightly changed after image compression, and a steganographic algorithm can resist JPEG image compression, so that the robustness of the steganographic image can be improved.

The invention discloses a digital image authenticity identification method based on a CFA interpolation characteristic. The method comprises a step of extracting a spectral variation and a chrominancedistortion characteristic in blocks to reflect the CFA interpolation characteristic according to a spectral difference between an interpolated image and an ideal full-color image, a step of calculating an interpolation characteristic change before and after re-interpolation to be a forensic characteristic, and a step of classifying by using a support vector machine and authenticating the image isaccording to the inconsistency of forensic characteristics between adjacent blocks. Compared with the prior art, the influences of JPEG image compression, image content and imaging device changes canbe effectively resisted, and the robustness is improved.