摘要:
The quantization factor for each block of pixels in an image or video encoding or transcoding method is determined. The blocks of pixels are classified according to predefined criteria and the blocks are processed according to the resulting classification. The predefined criteria include, for example, anticipated characteristics of the blocks after quantization, such as the transform coefficients after quantization and/or the total number of non-zero transform coefficients.
摘要:
This invention relates to method and apparatus for subpixel-based down-sampling. This invention implements an adaptive filter 140 based on edge detection, which removes visible color fringing artifacts while efficiently retaining sharpness.
摘要:
A novel method, system, and apparatus for efficient multi-block motion estimation in a digital signal compression and coding scheme. This invention selects only a few representative block sizes for motion estimation when certain favourable conditions occur, rather than using all available block sizes. This invention produces significantly reduced computational costs with virtually no sacrifice in visual quality and in bit-rate.
摘要:
A device or method for video compression uses a technique in which changes in the image are encoded by motions of block of the image and signals indicating evolutions in the block. To determine the motions of the blocks of a each frame, a search is performed for a similar block of a previous frame based on points of the previous frame which are arranged in successive diamond shaped zones. The diamond shaped zones may be centred on the position of the block in previous frame, or one or more predicted motions of the block. The method terminates according to criteria defined using thresholds.
摘要:
We propose modifying the error-diffusion method for transforming a grey-scale image into a halftone image, so that binary data is hidden in the resulting halftone image. Simultaneously, a second halftone image is generated by error diffusion, not storing the hidden data. The hidden binary data is typically a binary image, and the dark regions of this binary image can be seen when the two halftone images are overlaid.
摘要:
We propose methods for generating a halftone image, in which each pixel takes one of two tone values. The generated image contains hidden data, which is present at data storage pixels chosen using a pseudo-random number generator. In a first case, the data is hidden within an existing halftone image by reversing the tone value at certain of the data storage pixels, and at pixels neighbouring the data storage pixels. In a second case, the halftone image is generated from a grey-scale image, and data is hidden during this conversion process.
摘要:
A method and an apparatus relates to examining respective collections of coefficients out of a plurality of collections of coefficients according to a global coding order of the plurality of collections of coefficients, the respective collections of coefficients having respective priority levels as well as respective pluralities of coding units and truncation points which correspond to the coding units. In response to determining that an examined collection of coefficients out of the plurality of collections of coefficients has a priority level equal to a global priority level, encoding a first un-encoded coding unit according to a local coding order of the collection of coefficients and reducing the priority level of the collection of coefficients; and after each of the collections of coefficients in the plurality are examined, decreasing the global priority level. Repeating the examining, the encoding, the reducing and the decreasing for the plurality of collections of coefficients, and terminating the examining, the encoding, the reducing, and the decreasing in response to determining that a total amount of bits used is greater than a target bit rate.
摘要:
There is disclosed a method of digital signal compression, coding and representation, and more particularly a method of video compression, coding and representation system that uses multi-frame motion estimation and includes both device and method aspects. The invention also provides a computer program product, such as a recording medium, carrying program instructions readable by a computing device to cause the computing device to carry out a method according to the invention.
摘要:
There are disclosed three fast rate control methods that can efficiently reduce or remove the computation and memory usage redundancy over conventional PCRD methods. The first method, called successive bit-plane rate allocation (SBRA), assigns the maximum allowable bit-rate for each bit-plane of each code-block by using the currently available rate-distortion information only. The second method is called priority scanning rate allocation (PSRA). This first predicts the order of magnitude of each truncation point's rate-distortion slope and then encodes the truncation points based on the order (priority) information. The third method uses PSRA to obtain a significantly smaller amount of data than PCRD for optimal truncation and is called priority scanning with optimal truncation (PSOT). SBRA provides the highest computational complexity and memory usage reduction, and the lowest coding/transmission delay. The computational complexity reduction can be up to about 90% of the entropy coding process. However this method gives the lowest PSNR performance of the three. PSRA provides higher PSNR performance than SBRA with the penalty of lower memory usage reduction and higher delay. PSOT provides the best (optimal) quality while it is the least efficient method in term of computational complexity, memory usage and the coding/transmission delay. The three methods provide different degree of computation complexity and memory reduction, coding/transmission delay and PSNR performance. The most suitable rate control method can be chosen based on application requirements.
摘要:
We propose methods for generating a halftone image, in which each pixel takes one of two tone values. The generated image contains hidden data, which is present at data storage pixels chosen using a pseudo-random number generator. In a first case, the data is hidden within an existing halftone image by reversing the tone value at certain of the data storage pixels, and at pixels neighbouring the data storage pixels. In a second case, the halftone image is generated from a grey-scale image, and data is hidden during this conversion process.