摘要:
Disclosed is a method for converting an input digital color image having a set of possible input colors to an output digital color image having a set of palette colors, the number of palette colors being less than the number of possible input colors, wherein the set of palette colors is determined based on the distribution of colors in the input digital image boosted by a distribution of important colors contained in the input digital image.
摘要:
Disclosed is a method for converting an input digital color image having a set of possible input colors to an output digital color image having a set of palette colors, the number of palette colors being less than the number of possible input colors, wherein the set of palette colors is determined based on the distribution of colors in the input digital image supplemented by a distribution of important colors.
摘要:
Disclosed is a method for converting an input digital color image having a set of possible input colors to an output digital color image having a set of palette colors, the number of palette colors being less than the number of possible input colors, wherein the set of palette colors is determined based on the distribution of colors in the input digital image boosted by a distribution of important colors contained in the input digital image.
摘要:
A digital image processing determining the extent of blocking and contouring artifacts in a digital image includes the steps of: determining the extent of blocking artifacts using the column and row difference arrays; determining the extent of contouring artifacts based on an estimated DC quantization step size; and, determining a composite artifact measure as a function of the extent of blocking artifacts and extent of contouring artifacts. A digital image processing method determining the extent of contouring artifacts in the digital image includes the steps of: forming a column difference image; averaging the values in the columns in the column difference image to produce a column difference array; computing the average of the values in the column difference array that are separated by one block width to produce a block averaged column difference array; locating the peak value in the block averaged column difference array; repeating the above mentioned steps in the row direction; locating block boundaries based on the locations of peak values of column and row difference arrays; calculating DC value for each block; generating a histogram of the block DC values; calculating the Fourier transform of the histogram; locating the first non-DC peak in the Fourier transform domain; calculating a DC quantization step size based on the frequency of the first non-DC peak; and, employing the DC quantization step size as a measure of the extent of the contouring artifacts in the digital image.
摘要:
Disclosed is a method for converting an input digital color image having a set of possible input colors to an output digital color image having a set of palette colors, the number of palette colors being less than the number of possible input colors, wherein the set of palette colors is determined based on the distribution of colors in the input digital image boosted by a distribution of important colors contained in the input digital image.
摘要:
A digital image processing method for adaptively sub-sampling an image to X % of original pixels, includes the steps of generating an edge map of the image; normalizing the edge map to N-bits; applying a shift to the normalized edge map such that X % of the pixels will be ones when the normalized shifted edge map is halftoned using a blue noise halftoning technique; halftoning the edge map using the blue noise halftoning technique to generate a halftone mask; and sub-sampling the image at the pixel locations represented by ones in the halftone mask.
摘要:
A digital image processing method for generating a low resolution, low bit depth digital image from a higher resolution, higher bit depth input color digital image, includes the steps of: generating a gray scale image from the input color digital image; generating a low resolution sketch image from the grayscale image; generating a low resolution halftone image from the gray scale image; and combining the low resolution sketch image and the low resolution halftone image to form the low resolution, low bit depth digital image.
摘要:
A digital image processing method for generating a low resolution, low bit depth digital image from a higher resolution, higher bit depth input color digital image, includes the steps of: generating a gray scale image from the input color digital image; generating a valley image; filtering the valley image with a rank order filter to produce a filtered valley image; thresholding the filtered valley image to generate a binary valley image; generating a shadow image and a highlight image from the gray scale image; combining the shadow image, the highlight image, and the binary valley image to produce a combined binary image; and sub-sampling the combined binary image to a desired low resolution.
摘要:
A digital image processing method reduces noise and blocking artifacts in a digital image by first converting the RGB values of the digital image pixels to Y, Cb and Cr components, then detecting the block boundaries in the Y, Cb and Cr image components, and estimating the noise in the Y, Cb and Cr image components. One or more noise tables are constructed for the Y, Cb and Cr image components. An adaptive Huber-Markov-random-field-model-based filter (HMRF) is applied to the Y, Cb and Cr image components, wherein the adaptive feature of the HMRF employs the detected block boundaries and the noise tables to produce filtered Y, Cb and Cr image components. Finally, the filtered Y, Cb and Cr image components are converted to RGB components.