45 results about "Just-noticeable difference" patented technology

The invention discloses an image quality evaluation method based on a visual characteristic. The method is characterized by: firstly, converting original images into a xyY space or a LCH space, processing a component Y or a component C so as to obtain a group of test images; then, finding at least one JND (just noticeable difference) critical image; calculating differences of brightness (BR), color saturation (CS) and Gaussian function variance parameters in the original images and the JND critical image, wherein average values of the differences are the JND values of the BR, CS and contour rendering (CR) of the original images respectively; and then, carrying out mean calculation on the JND values of the different original images and determining the final JND values; taking the JND as a unit to change different attributes of the image at different degrees respectively; using a visual perception test to test the subjective image quality; then, using a regression analysis to establish a relation model of the image quality and the image attributes; and researching influences of the different attributes of the images according to a variance analysis. By using the method of the invention, influence on image quality which can be perceived by human eyes when improving the display parameter can be quantitatively evaluated.

The present invention relates to method and apparatus for video coding by ABT-based just noticeable difference (JND). For building the just noticeable difference model, spatial content information (SCI) is used to represent the spatial appearance similarity between one macroblock and its sub-blocks and the motion characteristic distance (MCD) is used to represent the motion characteristics similarity between one macroblock and its sub-blocks. For intra frames, the balance strategy based on the obtained SCI of the macroblock is used to generate the ABT-based JND model. For inter frames, the balanced strategy based on the obtained SCI and MCD of the macroblock is used to generate the ABT-based JND model. Using the ABT-based JND model, the residual coefficients for each block in a frame is filtered to obtain a reduced set of residual coefficients for transmission without degradation in visual quality.

The present invention relates to a watermarking method for protecting the copyright of digital data, which includes the step of dividing each of two successive frames into at least two sub-groups, the step of adding and subtracting a value, which varies according to pixel locations, to and from a specific component value at each pixel location of the sub-groups using Just Noticeable Difference (JND) values and averages of the specific component value at pixel locations of corresponding sub-groups of the two successive frames, the step of adaptively embedding watermark information while modifying embedment intensity of the watermark information, the step of calculating the averages of the specific component values of the sub-groups, and the step of extracting watermark information using the calculated averages.

The invention relates to an image coding method based on total variation, comprising the following steps of: (1) decomposing an input image (I) into a structure component (u) and a texture component (v); (2) analyzing the (u) at a coding end, selecting an analyzed area, mapping the (u) to the (v), and coding non-synthetic areas in the (u) and the (v) by using JPEG (Joint Photographic Experts Group) traditional coding mode; analyzing areas which need to be analyzed in the (v) by using a block connection method at a decoding end, v'' represents an analyzed result of a texture area, and u' and v' respectively represent compressed results of the non-synthetic areas in the (u) and the (v); (3) superimposing the u', the v' and the v'' at the coding end to obtain an image I', and I'' represents a result of the input image I which is compressed by the traditional FPEG; and under the same bit rate, judging whether the I' or the I''is nearer to the I by a JND (Just Noticeable Difference) model, then, if I'' is nearer to the I, reducing a decomposable model parameter lambda, returning to the step (1) to continue a whole process until the I' is nearer to the I as compared with the I'', finishing circulation, and selecting the I'. The invention can increase the coding quality of the image at the coding end.

A color sequential method for displaying images is suitable for applying in a display with pixels. Each of frames is formed by displaying a first sub-frame, a second sub-frame and a third sub-frame within a displaying time by the pixels. By calculating differences in gray levels between neighboring pixels, variations are gained. Then, a first just noticeable difference is provided, and the pixels having the variations larger than the first just noticeable difference are detected. Next, times of displaying the first, the second and the third sub-frames in the pixels are raised within the displaying time.

The invention discloses a depth significance-based stereopicture just noticeable difference (JND) model building method. The method comprises the steps: calculating the horizontal parallax of a stereopicture pair to obtain the horizontal parallax map of the stereopicture pair; calculating the depth value of the stereopicture pair to obtain a depth map of the stereopicture pair; calculating the depth significance of the stereopicture pair to obtain the depth significance map SD of the stereopicture pair; and building a depth significance-based stereopicture JND model. The method fully considers the depth significance influence factors in stereopicture noticing, the model obtained by adopting the method can more accurately reflect the feeling of eyes, the stereopicture processed by the guidance of the model can be added with more noise under the condition of keeping the subjective quality basically unchanged, thus being capable of removing vision redundancy in the stereopicture videos.

The invention discloses a visual perceptual coding method based on a multi-domain JND (Just Noticeable Difference) model and relates to video information processing. The method comprises the following steps: respectively calculating a space-domain basic JND threshold value, a luminance masking modulation factor, a contrast masking modulation factor and a time domain masking modulation factor of each transformation coefficient in a DCT (Discrete Cosine Transform) block by utilizing a time-space-domain multi-domain JND model so as to obtain the time-space-domain multi-domain JND threshold value of each transformation coefficient; introducing a block perception-based distortion probability evaluative criteria in the transform coding process, and searching a correction factor of each coefficient relative to the JND threshold value through an adaptive searching algorithm so as to obtain a transformation coefficient suppression value; and finally, subtracting the original transformation coefficient from the most appropriate suppression value obtained through corresponding calculation, and taking the coefficient as a novel coefficient to be put at an entropy coding stage. According to the coded suppression strategy of the multi-domain JND model and the block perception-based distortion probability, the coding rate can be effectively reduced on the premise of guaranteeing certain subjective quality, and the compression ratio of the current coding standard is further improved.

The invention discloses a JND (Just Noticeable Difference) value measuring method for the dark field brightness of an image. The method comprises the following steps: switching an original image to an xyY space, performing linear compression on a component Y according to different compression coefficients respectively, and increasing the dark field brightness of the image to obtain a group of test images; conducting a visual perception experiment to find at least one test image for serving as a JND critical image; and calculating the difference values of practical display brightness corresponding to the gray value of each pixel of the original image and the JND critical image, wherein the average value of the difference values is the JND value of the dark field brightness of the original image. The invention further discloses a JND value prediction method for the dark field brightness of an image. The JND value prediction method is used for predicting the JND value of the dark field brightness of the original image. Through adoption of the JND value measuring method and detection method, display parameters can be evaluated and improved quantitatively. In particularly, human eye noticeable influences on the dark field brightness of the image in parameter design specific to dark field brightness and contrast are lowered, so that a basis is laid for the design and research of a display technology.

The invention belongs to the field of video processing technology, and specifically discloses a method for sensing stereoscopic video coding based on a parallax just-noticeable difference model. The method comprises the following steps: (1) estimating parallax; (2) estimating a JND model based on the parallax; (3) calculating a brightness, texture and time weighted JND model; (4) combining the JND model based on the parallax with a spatial domain-time domain JND model by using a nonlinear additive model to obtain a binocular stereoscopic JND model based on the parallax; and (5) using the binocular stereoscopic JND model based on the parallax on a stereoscopic residual preprocessor for resetting a residual. The method disclosed by the invention can be used for effectively eliminating inter-view redundancy of time, space and binocular stereoscopic videos, and the information of the brightness, a texture region or an object edge keeps a very natural visual effect. Therefore, the method disclosed by the invention can be used for greatly reducing the stereoscopic video code rate on the premise of generating no influence on the stereoscopic visual perceptual quality.

The invention discloses a method and a device for coding a video based on region of interest (ROI) and just-noticeable difference (JND). The method comprises the following steps that whether the current macro block for frame image processing belongs to the ROI or not is judged; if the current macro block for frame image processing does not belong to an ROI, a transform domain JND model of the current macro block is built, and based on the transform domain JND model, forecasted residual error self-adjustment is conducted on the current macro block. The ROI and non-ROI in a frame image are separately processed, namely, conventional coding processing is conducted on macro blocks belonging to the ROI, and coding processing is conducted on macro blocks belonging to the non-ROI in the coding mode that forecasted residual error self-adjustment is carried out through transform domain JND; therefore, subjective coding quality is guaranteed, and coding rate is reduced.

The invention discloses an image brightness just noticeable difference (JND) value measurement method based on a region of interest. According to the method, an original image is converted into an xyY space, a component Y undergoes linear compression according to different compression coefficients, and the brightness of an original image is reduced so that a set of test images is obtained; then an visual perception experiment is carried out, and at least one test image is selected to serve as a JND critical image; an image brightness JND value based on the region of interest is calculated according to a binarization image of the region of interest of the original image. The invention further discloses an image brightness JND value prediction method based on the region of interest. 0.26 is taken as the brightness JND prediction value of the image based on the region of interest. According to the image brightness JND value measurement method based on the region of interest and the prediction method, parameters of a displayer and especially influences, capable of being noticed by human eyes, of parameters of brightness and the contrast ratio on image brightness can be assessed quantitatively and improved, and accordingly bases are provided for design and researching of display techniques.

The invention discloses a coding method and device for video images, belonging to the field of video codec processing. The invention includes extracting a luminance component from a video image, determining a distortion metric value, obtaining a first threshold and a second threshold corresponding to the video image according to the distortion metric value, determining a control parameter according to the first threshold and the second threshold, and based on the control parameter The video image is encoded to obtain an encoded video image. By using just perceivable error, it overcomes the problem of weak estimation of JND threshold in disordered regions in previous JND models, effectively eliminates spatial redundancy in video sequences, reduces coding amount, and improves coding efficiency. At the same time, the obtained luminance mask and spatial mask are used to estimate the JND of the ordered area more accurately, so as to better improve the perceived quality of the ordered area in the video and improve the overall viewing experience of the video.

The invention discloses a video encoding method and apparatus. The method comprises the following steps: according to each macro block in a to-be-encoded video image, dividing each macro block into a set number of sub macro blocks, wherein each sub macro block comprises at least two pixel points; calculating a JND value of each sub macro block according to a pre-stored just noticeable difference (JND) algorithm; determining the JND value of each macro block according to the JND value of each sub macro block; calculating a weight value of each macro block according to the JND value of each macro block and a pre-stored weight factor algorithm; determining an interval QP value of each macro block according to the weight value of each macro block, an initial QP value of each macro block and a preset interval QP algorithm; and determining a target QP value of each macro block according to the initial QP value of each macro block and/or the interval QP value of each macro block, and performing encoding according to the target QP value of each macro block. The encoding time consumption is reduced, and the encoding instantaneity is guaranteed.

The embodiment of the invention discloses a JND (Just-noticeable difference) based video encoding method and device. According to the invention, a plurality of sub-models of a JND model are built, a foundational model is determined from the sub-models, threshold superposition is performed according to weighting coefficients of other sub-models except for the foundational model by taking the foundational model as a foundational threshold, and an offset effect of different sub-models is deducted at the same time so as to acquire a more accurate JND model and a more accurate threshold. The method and the device disclosed by the invention solve technical problems that the JND model is inaccurate and the quality of compressed video is reduced in the prior art because of the direct superposition threshold calculated via multiplication by taking effects of the plurality of sub-models as weighting coefficients.

The invention provides a 3D (Three Dimensional)-mode color cast improving method, which comprises the steps of: 1, correction of analog/digital conversion; 2, gamma correction; 3, verification of just noticeable difference, wherein the gamma correction comprises 2D-mode gamma correction and 3D-mode gamma correction, and the 3D-mode gamma correction comprises color correction of 3D-mode color cast and correction value memory management. Compared with the prior art, the 3D-mode color cast improving method disclosed by the invention has the advantages that by means of the color correction of the 3D-mode color cast and the correction value memory management, the repeated gamma correction and the verification of the just noticeable difference under the 3D mode are avoided, and thus, the gamma correction and the verification of the just noticeable difference only need to be carried out under the 2D mode. Accordingly, the 3D-mode color cast problem can be improved effectively, the time for the gamma correction and the verification of the just noticeable difference is shortened, and the production efficiency is improved.

A method of measuring motion blur is disclosed comprising obtaining a moving edge temporal profile r₁(k) of an image of a high-contrast moving edge, calculating the masked local contrast m₁(k) for r₁(k) and the masked local contrast m₂(k) for an ideal step edge waveform r₂(k) with the same amplitude as r₁(k), and calculating the measure or motion blur Ψ as a difference function,

Ω=S(ΔxΣ_k|m₁(k)−m₂(k)|^β)^1/β.

The masked local contrasts are calculated using a set of convolution kernels scaled to simulate the performance of the human visual system, and Ψ is measured in units of just-noticeable differences.