摘要:
A bit rate control mechanism for a digital image or video compression system estimates a complexity parameter for a current picture, or block of samples, of a video signal as a function of parameters for a prior picture of the video signal, which parameters include a bit rate. From the complexity parameter a quality factor for the current picture is determined and applied to a quantizer to compress the current picture. A complexity pre-processor may also be used to detect scene changes in the video signal prior to estimating the complexity parameter. If there is a scene change detected, then the rate control mechanism is reset prior to estimating the complexity parameter for the first picture in the new scene. Also a video buffer verifier is controlled so that the buffer occupancy at the end of a specified image sequence is at a target value so that looping and editing applications are facilitated.
摘要:
A bit rate control mechanism for a digital image or video compression system estimates a complexity parameter for a current picture, or block of samples, of a video signal as a function of parameters for a prior picture of the video signal, which parameters include a bit rate. From the complexity parameter a quality factor for the current picture is determined and applied to a quantizer to compress the current picture. A complexity pre-processor may also be used to detect scene changes in the video signal prior to estimating the complexity parameter. If there is a scene change detected, then the rate control mechanism is reset prior to estimating the complexity parameter for the first picture in the new scene.
摘要:
A method of coarse representation of a visual object's shape for search/query/filtering applications uses a binding box that fully encompasses the object of interest within the image to extract a feature vector. Once the feature vector is available, matching based on specific queries may be performed using a search engine to compare the query number to an appropriate element of the feature vector, performing sorting to pick the best matches.
摘要:
A method of modifying a group of pictures (GOP) structure in an MPEG video signal from a low-delay mode bitstream having I and P pictures to a non-low-delay bitstream having I, P and B pictures uses the motion vectors from the low-delay mode bitstream to derive the motion vectors for the non-low-delay mode bitstream. Motion vectors for anchor pictures for the non-low-delay mode bitstream are converted from the motion vectors for the corresponding pictures in the low-delay mode bitstream. Motion vectors for the B pictures in the non-low-delay mode bitstream are converted from the motion vectors for the corresponding P pictures in the low-delay mode bitstream. The converted motion vectors for the non-low-delay mode bitstream are used in recoding an uncompressed video signal derived from the low-delay mode bitstream to produce the non-low-delay mode bitstream.
摘要:
A method of extracting regions of homogeneous color from a digital picture divides the digital picture into blocks and generates a feature vector for each block as a set of moments of the data for the block. The distance between the feature vector of each block and the feature vectors of the nearest neighboring blocks are determined using either a weighted Euclidean distance metric or a probability mass function-based distance metric. The maximum distance is the gradient value for the block, and the set of gradient values over all the blocks form a color gradient field. The gradient field is digitized and smoothed, and then segmented into regions of similar color characteristics using a watershed algorithm.
摘要:
A histogram-based segmentation of an image, frame or picture of a video signal into objects via color moments is initiated by defining a relatively large area within the object. The defined area is characterized by its color information in the form of a limited set of color moments representing a color histogram for the area. Based upon the set of color moments, color moments generated for small candidate blocks within the image, an automatically generated weighting vector, distance measures for the blocks from a central block in the object and a tolerance the area is grown to encompass the object to the extent of its boundaries. The initial set of color moments are then updated for the entire object. Those candidate blocks within the object serve to segment the object from the image.
摘要:
A method of generating a 2-D extended image from a video sequence representing a natural 3-D scene first determines motion parameters for a camera that recorded the scene with respect to a bakcground object from the video sequence using a structure-from-motion algorithm. The motion parameters include a rotation matrix, a translation vector and a depth map representing the depth of each point in the background object from the camera. Next from the motion parameters and depth map the 2-D extended image is generated for the background object as a composition of the images from the video sequence using a plane perspective projection technique. The background object may be layered as a function of depth and flatness criteria to form a set of layered 2-D extended images for the background object from the video sequence.
摘要:
A histogram-based segmentation of images in a video signal via color moments is initialized by a user defining regions in objects of interest from one or more images, key frames or pictures of the video signal. For each rectangle a normalized average color moment and associated co-variance matrix are determined which define a color class for that rectangle. From the normalized average color moment and associated co-variance garbage parameters are generated. Segmentation is then performed on a block basis on each image of the video sequence, a normalized color moment being generated for each block. Using a log likelihood test the closest color class for the block is determined. Based upon the closest color class and the garbage parameters for that color class a final determination is made in a two stage test as to whether the block belongs to the closest class or to a “garbage” class. All the continguous blocks that belong to a specific color class form the segmented object, and all of the objects are segmented in this manner.
摘要:
A semi-automatic method of tracking color objects in a video image sequence starts by separating the objects on the basis of color and identifying an object of interest to track. A Kalman predictive algotithm in used to predict the position of the centroid of the object of interest through successive frames. From the predicted position the actual centroid is measured and the position and velocity are smoothed using a Kalman filter. Error recovery is provided in the event the centroid falls outside the field of view or falls into an area of a different color, or in the event the tracking algorithm breaks down.
摘要:
Implementations generally relate to pre-charge phase data compression. In some implementations, a method includes computing prediction values for image data, where the image data is pre-charge phase data. The method also includes computing residual data based on the prediction values. The method also includes quantizing the residual data. The method also includes entropy encoding the quantized residual data. The method also includes refining an inverse quantized residual data based on one or more of the residual data and a number of left-over bit-budget after entropy encoding.