Abstract: Various implementations address distortion and quality measurements related to, for example, freeze-with-skip and/or a freeze-without-skip events. In several implementations, information is accessed indicating that a first and second set of one or more consecutive pictures are not to be displayed. A first and second indicator are determined. In one such implementation, the first and second indicators indicate an amount of distortion across one or more types of distortive effects that result from displaying substantially a first, or second, same picture during a display time for the first, or second, set of pictures. The first and second indicators are combined in a non-linear manner. In another such implementation, the distortion is associated with a given type of distortive effect, from among multiple types of distortive effects, and the first and second indicators are combined for the given type of distortive effect.

Abstract: Various implementations address distortion and quality measurements. Certain implementations relate to distortions resulting in a freeze-with-skip and/or a freeze-without-skip. In one implementation, a pause term provides an indication of distortion associated with a pause arising from not displaying one or more consecutive pictures that are not to be displayed. A motion term provides an indication of distortion associated with a related change in motion. A combined indicator is based on an addition of the pause term and the motion term. In another particular implementation, a first indicator indicates distortion across one or more types of distortive effects that results from not displaying a first set of pictures. A second indicator indicates corresponding distortion with respect to a second set of pictures. The first indicator and the second indicator are combined in a non-linear manner.

Abstract: Methods and apparatus for artifact detection are provided by the present principles that measure the level of artifacts, such as those caused by temporal concealment of errors due to packet loss, for conditional error concealment. The principles are based on an assumption that sharp edges of video are rarely aligned with macroblock boundaries so video discontinuities are checked throughout the video. The scheme solves the problem of error propagation when temporal concealment of artifacts is used and the high false alarm rates of prior methods. Artifact detection methods are provided for regions of an image, an entire image, or for a video sequence, with error concealment provided conditionally based on the artifact levels.

Abstract: The invention is made in the technical field of video quality measurement. More precisely, the invention is related to mean observer score prediction using a trained semi-supervised learning regressor. That is, a method and apparatus for measuring video quality using a semi-supervised learning system for mean observer score prediction is proposed. Said semi-supervised learning system comprises at least one semi-supervised learning regressor and said method comprises training the learning system and retraining the trained learning system using a selection of test data wherein the test data is used for determining at least one mean observer score prediction using the trained learning system and the selection is indicated by a feedback received through a user interface upon presenting, in the user interface, said at least one mean observer score prediction. Doing so, prediction quality can be improved after re-training at least for the selection.

Abstract: A method for processing an image divided into blocks of pixels is disclosed. The method comprises the steps of: detecting, for each block, a largest sub-block whose pixels have an equal luminance value; identifying, for each block, if the detected largest sub-block is or is not a natural texture; determining, for each block, a block blockiness level on the basis of the number of pixels within the detected largest sub-block and on the basis of the identification step; and processing the image on the basis of the block blockiness levels.

Abstract: The purpose of an objective video quality evaluation is to automatically assess the quality of video sequences in agreement with human quality perception. The invention addresses the effects of the introduction of a temporal dimension by focusing on the temporal evolutions of spatial distortions, since it has been found that a spatial quality variation cannot be evaluated by simple subtraction of the spatial quality of neighboring frames. An improved method for estimating perceived video quality comprises steps of calculating a first similarity map between adjacent frames of a current sequence, calculating a second similarity map between the corresponding reference frames, and calculating (smg3) a third similarity map, which provides a numerical quality value.

Abstract: A method and apparatus for measuring the quality of a video sequence, which includes a plurality of frames, among which one or more consecutive frames are lost, wherein during the displaying of the video sequence, the one or more lost frames are substituted by an immediate preceding frame in the video sequence during a period from the displaying of the immediate preceding frame to that of an immediate subsequent frame of the one or more lost frames, the method includes measuring the quality of the video sequence as a function of a first parameter (DF) relating to the stability of the immediate preceding frame during the period, a second parameter (DD) relating to the continuity between the immediate preceding frame and the immediate subsequent frame, and a third parameter (DP) relating to the coherent 20 motions of the video sequence.

Abstract: A method for determining a motion vector for a current video frame block comprises determining the motion vector using full search. Then, a number of further motion vectors is counted which is the number of motion vectors of neighbouring blocks which are similar to each other and the motion vector. Then it is ascertained that the number meets or exceeds a threshold and that the motion vector is not similar to at least one of the counted further motion vectors. A search region is determined using counted motion vectors and searched for a local best match of the current block. The motion vector is changed towards referencing the local best match. The search region only comprises candidates referenced by motion vector candidates similar to a yet further motion vector pointing to a centre of the further search region. Then, the motion vector resembles the motion presumed by the HVS.

Abstract: The present invention provides a method and corresponding apparatus for measuring the quality of a video sequence. The video sequence is comprised of a plurality of frames, among which one or more consecutive frames are lost. During the displaying of the video sequence, said one or more lost frames are substituted by an immediate preceding frame in the video sequence during a period from the displaying of said immediate preceding frame to that of an immediate subsequent frame of said one or more lost frames. The method comprises: measuring the quality of the video sequence as a function of a first parameter relating to the stability of said immediate preceding frame during said period, a second parameter relating to the continuity between said immediate preceding frame and said immediate subsequent frame, and a third parameter relating to the coherent motions of the video sequence.

Abstract: The purpose of an objective video quality evaluation is to automatically assess the quality of video sequences in agreement with human quality perception. The invention addresses the effects of the introduction of a temporal dimension by focusing on the temporal evolutions of spatial distortions, since it has been found that a spatial quality variation cannot be evaluated by simple subtraction of the spatial quality of neighbouring frames. An improved method for estimating perceived video quality comprises steps of calculating a first similarity map between adjacent frames of a current sequence, calculating a second similarity map between the corresponding reference frames, and calculating (smg3) a third similarity map, which provides a numerical quality value.

Abstract: The invention is made in the technical field of video quality measurement. More precisely, the invention is related to mean observer score prediction using a trained semi-supervised learning regressor. That is, a method and apparatus for measuring video quality using a semi-supervised learning system for mean observer score prediction is proposed. Said semi-supervised learning system comprises at least one semi-supervised learning regressor and said method comprises training the learning system and retraining the trained learning system using a selection of test data wherein the test data is used for determining at least one mean observer score prediction using the trained learning system and the selection is indicated by a feedback received through a user interface upon presenting, in the user interface, said at least one mean observer score prediction. Doing so, prediction quality can be improved after re-training at least for the selection.

Abstract: The invention relates to a method for processing an image divided into blocks of pixels comprising the steps of: detecting, for each block, a largest sub-block whose pixels have an equal luminance value; identifying, for each block, if the detected largest sub-block is or is not a natural texture; calculating, for each block, a weighted luminance difference between the detected largest sub-block and neighboring pixels; determining, for each block, a block blockiness level on the basis of the number of pixels within the detected largest sub-block, of said identification step and of said weighted luminance difference; and processing the image on the basis of the block blockiness levels.

Abstract: A method for processing an image divided into blocks of pixels is disclosed. The method comprises the steps of: detecting, for each block, a largest sub-block whose pixels have an equal luminance value; identifying, for each block, if the detected largest sub-block is or is not a natural texture; determining, for each block, a block blockiness level on the basis of the number of pixels within the detected largest sub-block and on the basis of the identification step; and processing the image on the basis of the block blockiness levels.

Abstract: The invention relates to a method for encoding a plurality of non overlapping blocks in a picture. The method comprises the steps of: transforming each of the blocks into a transformed block of coefficients in the frequency domain by applying a predefined transform; scanning the coefficients of at least two neighboring transformed blocks jointly from the lowest frequency to the highest frequency according to a predefined scanning pattern, the group of at least two neighboring transformed blocks being called super-block; and entropy coding the scanned coefficients of the super-block into an entropy coded group of bits.