34 results about "Just noticeable distortion" patented technology

The invention, which belongs to the technical field of image / video coding, relates to a level selection visual attention mechanism-based image just-noticeable-distortion (JND) threshold calculating method in a pixel domain. According to the technical scheme, the provided method comprises the following steps: S1, calculating a background brightness adaptive threshold for an original input image; S2, calculating an edge-based texture masking threshold for an image; S3, adding the brightness adaptive threshold obtained in the step S1 and the texture masking threshold obtained in the step S2 and subtracting a superposed portion of the two threshold so as to obtain a basic JND threshold; S4, according to the size of the input image, setting a level value of level selection; S5, carrying out downsampling on the original input image at different resolution ratios and carrying out saliency map detection on the image at the different resolution ratios by utilizing a quaternion fourier phase spectrum (PQFT) saliency detection method; and S6, carrying out sampling on the saliency map at different resolution ratios so as to obtain the resolution ratio of the original image. According to the invention, more noises can be accommodated; and a good visual quality is realized.

The invention publishes a perceptual video compression method based on a just noticeable distortion (JND) and auto-regressive (AR) model, comprising a texture region dividing algorithm and a synthesis algorithm based on the AR model. The texture region in a video is divided by using the dividing algorithm based on the JND and then the texture region is synthesized by using the AR model. The invention provides a space-time JND model and accurately and effectively divides the texture region. An AR model is designed, which ensures the video quality and greatly improves the real-time performance through simple calculation. A video compression technology in combination with eye vision characteristic is developed, which improves the video compression efficiency and reduces the bit rate.

The invention discloses a stereoscopic video bitrate control method based on binocular just-noticeable distortion. Bitrate control is performed through a viewpoint layer, a group of picture layer, a frame layer and a macro-block layer. In the viewpoint layer, a first group of picture is pre-coded to obtain bitrate allocation weight of left and right viewpoints; in the group of picture layer, the target number of bits is allocated for each group of picture according to the remaining number of bits in the viewpoints, a frame rate, the length of the groups of picture and a buffer occupancy rate, and an encoding quantization parameter of a key frame in each group of picture is determined; in the frame layer, the target number of bits is allocated for each frame except the key frame according to the remaining number of bits in the groups of picture and the buffer occupancy rate; and in the macro-block layer, the target number of bits allocated to each macro-block in each frame except the key frame is calculated, and an encoding quantization parameter for each macroblock is determined. The above bitrate control method allows bitrate control results to be more consistent with human visual characteristics under definitive bitrate conditions and can be used for obtaining good subjective quality.

Blocks in pixel images are template matched to select candidate blocks and weights according to a structural similarity and a perceptual distortion of the blocks. The perceptual distortion is a function of a just-noticeable-distortion (JND). A filter outputs a prediction residual between the block and the candidate blocks. The prediction residual is transformed and quantized to produce a quantized prediction residual using the JND. The matching and quantizing is optimized jointly using the perceptual distortion. Then, the quantized prediction residual and the weights are entropy encoded into a bit-stream for later decoding.

The invention relates to a fast adaptive loop filter algorithm based on a just noticeable distortion (JND) model, which comprises the steps of establishing a JND model, dividing image frames into a region-of-interest (ROI) and a region-of-non-interest (RONI) by using the JND model, dividing the RONI into a region-of-non-interest smooth region (RONISR) and a region-of-non-interest texture region (RONITR) by using a Canny operator, and dividing the ROI into a region-of-interest smooth region (ROISR) and a region-of-interest texture region (ROITR) by using the Canny operator; and carrying out adaptive filtering. According to the invention, an ALF (adaptive loop filter) method is optimized in allusion to an HEVC (high efficiency video coding) structure by being combined with the pixel-domain JND model and the Canny operator, perceptive redundancy in video is removed, and the coding efficiency is improved; and a region which does not need ALF processing can be found out quickly, and the complexity of the adaptive loop filter algorithm is greatly reduced under the condition of not influencing the quality.

An image encoding method and apparatus capable of improving image compression efficiency by using human psycho-visual characteristics are provided. In the image encoding method and apparatus, an image signal component of which amplitude is equal to or less than a just noticeable distortion (JND) that is a minimum limit of a visually noticeable image is not encoded according to image characteristics by using the masking effect of the human visual system (HVS), thereby improving an image compression rate without visible deterioration of image quality.

The invention provides a stereoscopic video B frame error concealment method based on eye perception. A traditional error concealment technology cannot well adapt to the new standard HEVC and the extended new multi-view standard MV-HEVC. The method comprises the steps that lost blocks in a stereoscopic video are partitioned into static blocks and motion blocks; and then different restoration modesare adopted for the different lost block types, a direct copy mode is selected for the static blocks, and the motion blocks are restored by using a stereoscopic video error concealment algorithm based on a binocular just noticeable distortion model, wherein the motion blocks are restored through the specific steps that adaptive size partitioning is conducted, a candidate motion-disparity vector set is built, BJND model-based matching criterion values are calculated, and finally an optimal motion vector is selected for restoration. According to the method, the characteristics of the new standard are combined, the existing error concealment method is improved, the distortion characteristic of eyes for video pictures is considered, and a very good restoration effect is achieved on the network packet loss phenomenon of the stereoscopic video in network transmission.

The invention relates to distributed encoding method and system based on HVS / ROI (human vision system and region of interest) and belongs to distributed encoding methods and systems. The system comprises an encoder and a decoder. The encoder divides an input video Wyner-Ziv frame into macroblocks C and macroblocks AC by an HVS JND (just noticeable distortion) model, and macroblocks of a K frame and macroblocks of the WZ frame are encoded independently. The decoder is used for joint decoding of received code streams. The HVS JND model is introduced, so that data processing and transmission of JND thresholds in next region are reduced, transmission rate is reduced, and energy consumption and bandwidth are economized. A glare region with high movement violence and brightness contrast is subjected to ROI extraction and is subjected to entropy encoding, and subjective quality is improved while encoding complexity is not increased as far as possible.

The invention discloses a three-dimensional image fragile watermark method based on joint just noticeable distortion and in particular relates to a three-dimensional image location tampering and restoring fragile watermark algorithm based on JJND (Joint Just Noticeable distortion). Firstly, a three-dimensional image block is divided into a relative sensitive block and a relative insensitive block according to a JJND model and the number of three-dimensional image match blocks, then discrete cosine transform and quantization compression are carried out on the image blocks to generate watermarks, and unsymmetrical watermark embedding of different type blocks of the three-dimensional image is built according to the JJND model and types of the image blocks. Restored watermarks can be used for locating the positions of the tampered portions to further improve transparency of the image. Meanwhile, copy embedding of the restored watermarks in the three-dimensional image can improve the capacity for the watermarks to restore tampered information. Experiments show that the three-dimensional image fragile watermark method based on the joint just noticeable distortion is accurate in location on the tampered positions and has higher restoring capacity on the tampered areas.

The invention discloses a multi-view video rate control method based on exactly perceptible distortion. An exactly perceptible distortion value can be obtained according to characteristics of visual system of human beings. Rate control is performed quantificationally in a multi-view video, namely, according to an frame I or frame P image, a quantization parameter is determined according to an average value of quantization parameters of frame B images of a last image set and according to a Frame B image, due to calculation of the number of target bits distributed to the Frame B image in advance and calculation of the number of the target bits distributed to each macro block of the Frame B image in advance, a mean absolute error of each macro block is corrected combined with the exactly perceptible distortion value. Then according to a secondary model of a code rate-quantization parameter, a quantization parameter of each macro block is calculated. According to the code control method, under the conditions that a control code rate is accurate and a peak signal to noise ratio is kept unchanged, higher subjective quality is obtained and when the corrected peak signal to noise ratio is regarded as a quality standard, the code rate of the multi-view video rate control method based on the exactly perceptible distortion is reduced by 10.31%-32.13%.

The invention discloses a measurement method for a space-time domain self-adaptive just noticeable distortion. The method is characterized by comprising the following steps: step one, integrating pattern masking effect PM and luminance adaptation LA to obtain a space-domain JND (Just Noticeable Distortion) threshold JNDS; step two, integrating four time domain sensing parameters including relativemovement I (vr), background movement U(vg), time domain duration I (Tau) and residual fluctuation intensity U (Delta) to obtain a time-domain JND adjusting weight coefficient z; and step three, performing adjusting by using the time-domain JND adjusting weight coefficient z on the basis of the space-domain JND threshold JNDS, thereby obtaining a space-time domain JND threshold JNDST.

The invention discloses an objective stereo image quality assessment method based on a perception feature set. According to the method, the distortion degree of a stereo image is measured according to the distortion degree of a visual perception feature map, a saliency map, a gradient map and an airspace just noticeable distortion map which are related to viewpoint perception quality are extracted, a disparity map related to third dimension and quality is extracted, distortion degrees of four perception feature maps are taken as features of the stereo image to create the perception feature set, a complicated human vision system is simulated according to a random forest machine learning algorithm, and feature parameters are fused. The objective stereo image quality assessment method has the advantages that change conditions of visual quality under the condition that the stereo image is influenced by various image processing and compressing methods can be reflected objectively, assessment performance of the method is not influenced by the content of the stereo image and the type of distortion, and conformity with subjective perception of human eyes is achieved.

The invention relates to an image adaptive measuring method based on compressed sensing. The operation steps of the method are as follows: (1) a just noticeable distortion threshold model is built for an input image; (2) measurement is performed by adopting different measuring numbers in an adaptive manner on different image areas; (3) partitioning orthogonal matching pursuit reconstruction is performed; and (4) inverse Discrete Cosine Transformation is performed and an image is generated. The image adaptive measuring method has made improvement in the measuring process of image compressed sensing, changes a conventional method of performing single number measurement on all areas of the image, and adopts adaptive measurement on the different areas of the image according to visual characteristics of human eyes. The image adaptive measuring method helps to improve the compression efficiency of the image when the subjective quality and the objective quantity are guaranteed to remain unchanged.

The invention discloses a macro block mode fast selecting method based on just noticeable distortion. A just noticeable distortion image of a time-space domain corresponding to each color image in color television video sequences to be processed is obtained, a just noticeable distortion value of each image block in the just noticeable distortion image of the time-space domain is calculated, and then an optimal macro block encoding mode of each macro block in a B-frame color time-space domain is confirmed according to the just noticeable distortion value of each image block in the just noticeable distortion image of the time-space domain. The macro block mode fast selecting method can effectively save encoding time of color videos on the premise that color video visual perception quality is guaranteed and greatly reduces the encoding complexity level of the color videos, and saved encoding time can reach to 72.7% averagely.

The invention discloses a depth video coding method on the basis of a foveal JND (just noticeable distortion) model. The depth video coding method comprises the following steps of: firstly, calculating the global JND of each pixel in each frame in a middle virtual viewpoint video obtained by carrying out middle virtual viewpoint rendering on color videos at left and right viewpoints and depth videos at left and right viewpoints; then, according to the global JND, obtaining a middle virtual viewpoint video subjected to geometrical offset; according to the geometrical offset, obtaining the maximum tolerable distortion video of the depth video at the left viewpoint; and finally, obtaining increasable coded quantization parameters of each macro block in each frame of the depth video at the left viewpoint according to the maximum tolerable distortion video. According to the method disclosed by the utility model, on the premise of maintaining the visual perception quality of virtual viewpoints, the encoding rate of the depth videos is effectively saved, the compressed coding efficiency of a depth video sequence is also greatly improved, and code streams can be saved by 11.00% to 23.34%.

The invention discloses a method for quickly coding multi-view color videos based on binocular just perceptible distortion. The method includes the first step of utilizing parallax error information the left view video and the right view video to determine a binocular just perceptible distortion value of each macro block within a non-boundary area in each frame of right view image in the right view video, and the second step of terminating macro block mode selection in advance according to the binocular just perceptible distortion value. On the basis of not causing rate-distortion performance degradation, the method for quickly coding the multi-view color videos can effectively improve coding efficiency of the multi-view color videos. The saved coding time can reach to 66.48% to 71.90%, and saves the coding time by 68.46% on average.

The invention relates to a fast adaptive loop filter algorithm based on a just noticeable distortion (JND) model, which comprises the steps of establishing a JND model, dividing image frames into a region-of-interest (ROI) and a region-of-non-interest (RONI) by using the JND model, dividing the RONI into a region-of-non-interest smooth region (RONISR) and a region-of-non-interest texture region (RONITR) by using a Canny operator, and dividing the ROI into a region-of-interest smooth region (ROISR) and a region-of-interest texture region (ROITR) by using the Canny operator; and carrying out adaptive filtering. According to the invention, an ALF (adaptive loop filter) method is optimized in allusion to an HEVC (high efficiency video coding) structure by being combined with the pixel-domain JND model and the Canny operator, perceptive redundancy in video is removed, and the coding efficiency is improved; and a region which does not need ALF processing can be found out quickly, and the complexity of the adaptive loop filter algorithm is greatly reduced under the condition of not influencing the quality.

The invention discloses an image enhancement method under ambient light, and belongs to the field of image processing. The image enhancement method comprises the steps that the brightness value of an original image is extracted, a visibility threshold is determined, and a brightness enhanced image is determined through combination of light intensity of the environment in which display equipment is arranged. The gradient gain function of a display image is determined through combination of a just-noticeable-distortion model according to the light intensity of the environment in which the display equipment is arranged so that the enhanced display image under ambient light is acquired through a weighed optimization mode. A readability enhanced color display image is obtained through color spatial conversion. The brightness and the details of the display image are enhanced through a gradient domain optimization framework based on weighting so that readability of the display image under ambient light can be enhanced, the brightness of the display image is enhanced by using a nonlinear transfer function under ambient light, gradient loss caused by ambient light can be compensated by adopting the just-noticeable-distortion model, and finally readability of the image on the display equipment can be enhanced.

The invention discloses a fragile digital watermarking method for tampering and positioning stereoscopic image pixels. At the digital watermarking embedding end, the masking characteristic of binocular visual perception of human eyes, that is, the distortion that can be detected by both eyes, is used to guide the embedding of digital watermarking, so that the stereoscopic image Transparency and watermark embedding capacity have reached a good balance, and according to the high five-bit image information of the left and right viewpoints and the binocular just distortion model as the input of the MD5 hash function to generate a feature watermark image, and then use an adaptive method to embed the watermark information into In the left and right viewpoints of the stereoscopic image, through the above process, the security of the digital watermarking technology is guaranteed; in the process of tampering and positioning, the high five-bit feature watermark information of the attacked stereoscopic image is extracted, and then the watermark information of the attacked stereoscopic image is extracted , comparing the two types of watermark information to initially determine the tampering location, and then using the parallax information to further enhance the accuracy of the tampering location, which can effectively authenticate the authenticity and integrity of the stereoscopic image content.