33 results about "Color image compression" patented technology

It is an object of the present invention to improve the compression ratio of a color image and to clearly display the outlines of characters and the like. A hue cluster classifying / unifying unit reduces the number of hue values of each pixel in a color image, based on a hue histogram, allocates the number-reduced hue value to each pixel and classifies pixels with the same hue value into one cluster. Furthermore, the unit unifies clusters whose hue values are below a predetermined value. The unit also traces the outline of a cluster whose size is below a reference value and determines that a cluster that has a lot of change points belongs to a character area. An encoding unit determines the characteristic of each cluster, based on both an area determined by an area determining unit and whether the cluster belongs to a ruled line area or a character area, and encodes pixels in each cluster by a coding method suitable for the characteristic of the cluster.

The invention discloses an image compression method based on color classification and clustering. The compression method includes: acquiring an original image and establishing a flag matrix for the original image; performing color classification on the original image; judging the color Whether the number of types of classification is more than the preset number of color types, if so, cluster the excess color types in the color classification; split the pixel data and logo of the original image according to the classification of the color Data; using a lossless compression algorithm to compress the mark data, using a lossy algorithm to compress the pixel data; writing each compressed data into a file according to a preset order to obtain a compressed image. The invention classifies and clusters the color information of the image, combines the lossless compression algorithm and the lossy compression algorithm, and realizes an image compression method with high quality, high speed and high compression ratio.

The invention relates to a color image encryption system and an encryption and decryption method based on compression holography and belongs to the technical field of optical image encryption. The system comprises a laser device, a first reflecting mirror, a second reflecting mirror, a beam expanding and collimating system, a beam splitter, a first spatial light modulator, a second spatial light modulator, a third spatial light modulator, a fourth spatial light modulator, a first random phase mask, a second random phase mask, a third random phase mask, a high-speed image collecting device and a computer. Firstly, gray level images of three channels of color images are extracted and are arranged at the positions with different distances to a CCD to serve as object information needing to be encrypted, the three random phase masks are tightly attached to the three gray level images and then are used for modulating light beams containing the object information, the three light beams are interfered by a beam combining prism and reference light to generate a holographic image, and the gray level images of the three channels are simultaneously encrypted on the same holographic image. Lastly, decryption is carried out with a TwIST algorithm, and color image composition is carried out. According to the color image encryption system and the encryption and decryption method based on the compression holography, the color images can be encrypted through one-time exposure, and the encryption efficiency and the confidentiality degree of the encrypted information are improved.

The invention discloses a color image compression method, which relates to the technical field of image compression. The RGB color image is converted into a YCbCr4:4:4 format image by using an image color space conversion method, and then the luminance Y component and chromaticity in the YCbCr image are The Cb component and Cr component are changed, quantized, sorted, encoded, etc., and finally the compressed RGB color image is synthesized. Under the premise of effectively controlling the encoding bit rate, the brightness Y component and the chrominance Cb component and Cr component are separated. Processing to adjust the quantization error of the YCbCr image to effectively reduce the coding distortion of the RGB image and ensure the best quality of the compressed RGB image. At the same time, the coding rate of the component vectorization processing is not high, and the storage space and transmission cost are also low.

The invention discloses a coloring weight real-time separating method for coloring image compression bit stream, which comprises the following steps: detecting marks of a SOC marking segment and a SIZ marking segment for input bit stream, and starting to separate the coloring weight in the bit stream after detecting the marks; and performing different processing for different marking segments in the bit stream, and finishing the real-time separating operation of the coloring weight after receiving a bit stream ending mark. The invention further discloses a coloring weight real-time separating device, which comprises a shift register, a marking segment mark detecting and control module, a control bus, a SIZ marking segment processing module, a COD marking segment processing module, a QCD marking segment processing module, a COC marking segment processing module, a QCC marking segment processing module, a SOT marking segment processing module and a bit stream ending processing module. The invention achieves the JPEG2000 coloring weight separating function required by hardware, thus being advantageous for parallel execution of JPEG2000 decompression. The invention has good expandability and portability.

The invention discloses a quaternion field colored image compressed sensing recovery method based on a Quasi Newton algorithm. The quaternion field colored image compressed sensing recovery method comprises the following steps of: converting a colored image two-dimensional matrix to a two-dimensional matrix of the quaternion field; and carrying out compressed sensing on the two-dimensional matrix of the quaternion field once to recover the original colored image, so that the operation time is saved in comparison with a conventional method of carrying out compressed sensing on the three vectors, i.e. RGB (Red, Green, Blue) of the colored image respectively. According to the quaternion field colored image compressed sensing recovery method based on the Quasi Newton algorithm disclosed by the invention, a quaternion matrix signal is written into an Euler form of a quaternion, the amplitude and the phase are adopted as novel bound terms of compressed sensing optimization problems, therefore, the recovery effect is better in comparison with the conventional method which converts the data of the three channels, i.e. RGB of the colored image into three real-number two-dimensional matrixes for being processed respectively. According to the quaternion field colored image compressed sensing recovery method based on the Quasi Newton algorithm disclosed by the invention, the result image is a mean value of an image obtained by carrying out compressed sensing decoding in rows and an image obtained by carrying out compressed sensing decoding in columns, therefore, the obtained image is smoother than the image which is recovered by being processed only in rows or in columns.

The invention provides a color image compression and encryption method based on compressed sensing and double random encryption mechanism. This method first decomposes the plaintext image into three components R, G and B, and then DWT transforms them respectively, and then uses the index vector D 1 , D 2 , D 3 , D 4 Perform double random position scrambling on the sparse coefficient matrix, then perform compression measurement and quantization on the scrambled matrix, and perform simultaneous double random pixel value diffusion between and within the R, G, and B components of the quantized matrix, and finally obtain ciphertext image. The parameters and initial values ​​of the four-wing hyperchaotic system and the Logistic-Tent chaotic system are generated by using the plaintext image information and external key, and then the parameters and initial values ​​are brought into the Logistic-Tent chaotic system to generate the chaotic sequence to construct the measurement matrix; The parameters and initial values ​​are brought into the four-wing hyperchaotic system, and the generated four chaotic sequences are sorted to obtain four index vectors, which are respectively used in double random position scrambling and diffusion.

The invention provides a color image compression method based on a reaction-diffusion equation set. The color image compression method belongs to the field of image processing technologies. The colorimage compression method comprises the steps of: firstly, converting a color image into a grayscale image in a compression phase, compressing the grayscale image by using a JPEG compression method, then selecting a number of representative pixel points in the color image by utilizing a local optimal strategy, and only storing the compressed grayscale image and the selected representative pixel points to achieve the purpose of compression; and decompressing the stored data into the original color image by utilizing the reaction-diffusion equation set in a decompression phase. The color image compression method based on the reaction-diffusion equation set has the advantage of reducing a storage space of the color image, so that the display effect of the decompressed color image is clearer, and the details are more abundant, meticulous and the like.

A digital encoding and decoding method of high bit-depth gray scale medical images allows standard 3-channel color image compression algorithms to be used to compress and de-compress such encoded high bit-depth gray scale images without significant image quality loss. The digital encoding and decoding method may be used to improve the network transmission, storage and rendering of such gray scale images in a standard web browser.