497 results about "Lossy compression" patented technology

A digital watermarking process whereby an invisible watermark inserted into a host image is utilized to determine whether or not the image has been altered and, if so, where in the image such alteration occurred. The watermarking method includes the steps of providing a look-up table containing a plurality of coefficients and corresponding values; transforming the image into a plurality of blocks, wherein each block contains coefficients matching coefficients in the look-up table; and embedding the watermark in the image by performing the following substeps for at least some of the blocks: First, a coefficient is selected for insertion of a marking value representative of a corresponding portion of the watermark. Next, the value of the selected coefficient to used to identify a corresponding value in the look-up table. Finally, the identified coefficient is left unchanged if the corresponding value is the same as the marking value, and is changed if the corresponding value is different from the marking value. After the insertion of the watermark, the image may be stored in a lossy-compression form, thus permitting efficient storage and distribution. Moreover, the method may be used to produce two output signals for authentication: (1) a meaningful pattern to facilitate a quick visual check, and (2) an additional signal to detect unauthorized alteration. The method can be applied to an image compressed using JPEG or other techniques, such as Wavelet compression, and the marked image can be kept in the compressed format. Any alteration made on the marked image can be localized, making the method suitable for use in a "trustworthy" digital camera or camcorder.

An efficient method for compressing sampled analog signals in real time, without loss, or at a user-specified rate or distortion level, is described. The present invention is particularly effective for compressing and decompressing high-speed, bandlimited analog signals that are not appropriately or effectively compressed by prior art speech, audio, image, and video compression algorithms due to various limitations of such prior art compression solutions. The present invention's preprocessor apparatus measures one or more signal parameters and, under program control, appropriately modifies the preprocessor input signal to create one or more preprocessor output signals that are more effectively compressed by a follow-on compressor. In many instances, the follow-on compressor operates most effectively when its input signal is at baseband. The compressor creates a stream of compressed data tokens and compression control parameters that represent the original sampled input signal using fewer bits. The decompression subsystem uses a decompressor to decompress the stream of compressed data tokens and compression control parameters. After decompression, the decompressor output signal is processed by a post-processor, which reverses the operations of the preprocessor during compression, generating a postprocessed signal that exactly matches (during lossless compression) or approximates (during lossy compression) the original sampled input signal. Parallel processing implementations of both the compression and decompression subsystems are described that can operate at higher sampling rates when compared to the sampling rates of a single compression or decompression subsystem. In addition to providing the benefits of real-time compression and decompression to a new, general class of sampled data users who previously could not obtain benefits from compression, the present invention also enhances the performance of test and measurement equipment (oscilloscopes, signal generators, spectrum analyzers, logic analyzers, etc.), busses and networks carrying sampled data, and data converters (A/D and D/A converters).

Embodiments include implementing a remote display system (either wired or wireless) using a standard, non-custom codec. In this system, the decoder side can be fully implemented using an existing standard from a decode/display point of view and using a single stream type. The encoder side includes a pre-processing component that analyzes screen images comprising the video data to determine an amount of difference between consecutive frames of the screen images, divides each screen image into a plurality of regions, including no change regions, high quality regions, and low quality regions. The pre-processor characterizes each region as requiring a minimum quality level, encodes the low quality regions for compression in accordance with the H.264 encoding standard; and encodes the high quality regions using the lossless compression scheme of the H.264 standard. A no change region is encoded using a version of the H.264 encoding standard that adaptively and dynamically selects between lossless and lossy compression in a manner that optimizes efficiency of the compression operation.

The invention discloses a hybrid image compressing method based on block classification. In the invention, blocks are divided into text/ image block, natural image block and hybrid block according to different features of text/image area and natural image area of original images in the aspect of color and texture; then a compression mode in which palette coding, Hextile coding and LZW coding are combined is used in the text/ image block, a JPEG lossy compression mode is used in the natural image while the algorithm of the combination of the two modes is used in the hybrid block. The invention has the advantages that based on the block classification method, the text/image area and the natural image area can be divided up accurately, and that the blocks are respectively encoded can keep rather acuminate edge of the text/image block so as to enhance visual effect on the basis of ensuring higher compression efficiency and upgrade the peak signal to noise ratio of reconstructed images; the complexity of the algorithm is lower.

An image data compression system, for compressing a frame represented as a plurality of blocks, can include: a lossless compression unit to receive the plurality of blocks and to perform lossless compression thereon resulting in a first code; a lossy compression unit to receive the plurality of blocks and to perform lossy compression thereon resulting in a second code; and a code selection circuit to selectively output one of the first and second codes based upon a figure of merit evaluated for at least one of the first and second codes.

Methods and apparatuses for still image compression, video compression and automatic target recognition are disclosed. The method of still image compression uses isomorphic singular manifold projection whereby surfaces of objects having singular manifold representations are represented by best match canonical polynomials to arrive at a model representation. The model representation is compared with the original representation to arrive at a difference. If the difference exceeds a predetermined threshold, the difference data are saved and compressed using standard lossy compression. The coefficients from the best match polynomial together with the difference data, if any, are then compressed using lossless compression. The method of motion estimation for enhanced video compression sends I frames on an "as-needed" basis, based on comparing the error between segments of a current frame and a predicted frame. If the error exceeds a predetermined threshold, which can be based on program content, the next frame sent will be an I frame. The method of automatic target recognition (ATR) including tracking, zooming, and image enhancement, uses isomorphic singular manifold projection to separate texture and sculpture portions of an image. Soft ATR is then used on the sculptured portion and hard ATR is used on the texture portion.

The invention relates to lossless, near-lossless, and lossy compression and decompression of digital image data. Image data can be compressed and decompressed on-the-fly with no need for external RAM resources for temporary data storage while compressing/decompressing image data. Implementing the algorithm only requires a very limited amount of silicon and yields very high performance in relation to very low power consumption. The described implementation is optimized for raw image data from a sensor with a Bayer filter pattern but can be used on data from image sensors with any color filter. The compression algorithm contains a line indexing format which enables very fast subsampling of an already compressed image and the possibility to decompress only parts of an image—this improves performance and reduces the need for temporary RAM storage greatly when zooming and in postprocessing.

A low cost camera by implementing the major functions in host software is provided. This is accomplished by sending raw, digitized data from the camera directly to the host. The increased volume of raw data is handled by either an improved compression/decompression scheme using lossless compression, using lossy compression or using a shared bus with higher bandwidth. By moving such functions as color processing and scaling to the host, the pixel correction can also be moved to the host. This in turn allows the elimination of the frame buffer memory from the camera. Finally, the camera can use a low cost lens by implementing vignetting, distortion, gamma or aliasing correction with a correction value stored in a register of the camera for later access by the host to perform corrections.

Embodiments of the present invention are directed to a remote desktop communication protocol that includes spatial and temporal compression techniques. Multimedia presentation data is generated at a server from a source. A compression facility modifies the presentation data by both spatially and temporally compressing the presentation data to transmittable data. In some embodiments, a check is performed to ensure that the least amount of data is selected prior to sending the transmittable data to a remote client. The remote client receives the transmittable data and re-constructs the original multimedia presentation data. In some embodiments that use lossy compression, the reconstruction may not exactly re-construct the original multimedia presentation data. Once re-created, the remote client presents the presentation data at the remote client. The presentation data could be audio, video, or other data or a combination of them.

The present invention leverages a lossless pixel palettization scheme to locally compress portions of at least a two-dimensional image. This provides a lossless compression means with a compression ratio comparable with lossy compression means, allowing for efficient data transfers without loss of image information. By utilizing locally-adaptive palettization, two-dimensional pixel information can be exploited to increase compression performance. In one instance of the present invention, a locally-adaptive, lossless palettization scheme is utilized in conjunction with a one-dimensional compression scheme to yield a further increase in compression ratio. This allows for the exploitation of two-dimensional data information along with the further compression of information reduced to one dimension.

Compression of signal samples output from a parallel, time-interleaved analog to digital converter (TIADC) for a baseband signal, includes calculating first or higher order differences of consecutive signal samples followed by lossless or lossy encoding of the difference samples to produce compressed samples. Compression of a TIADC output signal with a nonzero center frequency, includes calculating sums or differences of pairs of signal samples separated by an appropriate number of sampling intervals followed by lossless or lossy encoding. The sums or differences of the signal samples have lower magnitudes than the original samples, allowing more efficient compression. Lossy compression alternatives produce compressed data with a fixed bit rate or with a fixed quality in the decompressed samples. Alternatives for lossy compression include attenuating the analog signal before sampling by the TIADC, applying bit shifters or multipliers after sampling to reduce the magnitudes of the signal samples, and lossy encoding.

An analog physiologic signal, e.g., the cardiac EGM, sensed by an IMD is filtered with a high pass filter (HPF), the cut-off frequency of the HPF being within a predetermined frequency bandwidth, wherein a low-band portion of the predetermined frequency bandwidth is attenuated in the filtered physiologic signal. The filtered physiologic signal is digitized in real time order, and the digital data set is filtered in reverse time order employing a digital IIR filter having characteristics substantially matching the cut-off frequency and filter characteristics of the HPF. When the system is implemented within an IMD, the filtered digital data set is compressed by lossy compression algorithm, and the compressed data set is filtered in reverse time order. In certain embodiments, the filtered digital data set is uplink telemetry transmitted to an external medical device, and the uplink telemetered data set is filtered in reverse time order employing a digital backward IIR filter resident in the external medical device.

A system for lossy compression of digital data for transmission to a remote location or to a storage medium and subsequently reconstructing the digital data includes an encoder which compares sequences of characters with an encoder database of data records to generate a compressed code. The compressed code includes pointer information relating to locations within the encoder database of data records corresponding within a given average distortion tolerance level per character to the sequences, and update information for the addition to the encoder database of new data records corresponding within the average distortion tolerance level per character to the sequences. The system also includes a decoder for receiving the compressed code, the receiver processing the compressed code to substantially reconstruct the digital data.

The invention relates to an image compression method, including the following steps: step (1), conduct gray scale detection on image blocks separated from the original image data, if gray image block, then execute step (2); otherwise execute step (3); step (2), conduct lossless compression on the gray image block, and execute step (6); step (3), calculate the number of different pixel values in the image block, if the number of different pixel values in the image block doesn't exceed the first threshold value, then execute step (4), if the number of different pixel values in the image block exceeds the first threshold value, then execute step (5); step (4), conduct lossless compression on the image block, and execute step (6); step (5), conduct lossy compression on the image block, and execute step (6); step (6), end. Therefore, the image compression method in the invention can self-adapt to adopting different compression methods based on difference of image contents, and use less resource to realize high quality image compression.