Back to results
US 8,027,065 B2Granted
Intelligent hardware for detecting color value of an image
AssigneeLexmark International, Inc.
InventorsMohamed Nooman Ahmed, Curt Paul Breswick, Gretchen Yvonne Gibson, Bob Thai Pham
Life of this patent
Estimating the term…
Abstract
Pixel characteristics, such as whether a pixel forms part of the background of an image, are evaluated by computing histograms from pixel color space components, by comparing pixel color space components to threshold values, or by other methods.
Claims20
A method for processing color pixel data of an image, comprising the steps of:
- computing with hardware using bit-shift operations an approximation of at least one of a plurality of other color space components of a pixel represented in RGB color space, wherein the at least one other color space component includes luminance, and an approximation of luminance (Y) is computed by summing a red component (R) of the pixel shifted a first number of bits, a green component (G) of the pixel shifted a second number of bits, and a blue component (B) of the pixel shifted a third number of bits;
- and
- evaluating a characteristic of the pixel in response to the computed approximation of the at least one of the plurality of other color space components, wherein the first number of bits is two, the second number of bits is one and the third number of bits is two;
- wherein the step of evaluating a characteristic of the pixel comprises comparing at least one of the computed other color space components of the pixels to a predetermined threshold value;
- and
- wherein computing at least one of a plurality of other color space components of a pixel represented in RGB color space further comprises the steps of:
- computing an approximation of chrominance component Cr of the pixel by computing ((R>>1)+(R>>2)−(R>>5))−((Y>>1)+(Y>>2)−(Y>>5)), wherein “X>>n” represents shifting RGB color space component X by n bits to the right;
- and
- computing an approximation of chrominance component Cb of the pixel by computing ((B>>1)+(B>>4))−((Y>>1)+(Y>>4)).
6 more elements
A method for processing color pixel data of an image, comprising the steps of:
- computing using hardware logic an approximation of one or more YCbCr color space components of a pixel represented in RGB color space, by bit-shifting each RGB color space component and adding or subtracting the bit-shifted RGB color space component to a resulting approximation value of the Y color space component, and by computing a Cr color space component approximation by performing an arithmetic operation on at least two instances of the Y color space component approximation each shifted by at least one bit, and at least two instances of the R color space component each shifted by at least one bit;
- and
- evaluating a characteristic of the pixel in response to the computed approximation of the one or more YCbCr color space components.
A system for processing color pixel data of an image, comprising:
- color space converter logic having bit-shift logic producing approximations of at least one YCbCr color space component of a pixel represented in RGB color space, the converter logic bit-shifts each RGB color space component and adds or subtracts the bit shifted RGB color space component to an approximation result value of the at least one YCbCr color space component, wherein an approximation of the Y color space component is computed by summing an R color space component shifted by two bits, the G color space component shifted by one bit, and the B color space component shifted by two bits;
- and
- a histogram generator producing a histogram from one of the computed color space component approximations of the pixels;
- wherein an approximation of the Cr color space component is computed by the color space converter logic by performing an arithmetic operation on at least two computed Y color space component approximations each shifted by at least one bit, and on at least two R color space components each shifted by at least one bit.
1 more element
A system for processing color pixel data of an image, comprising:
- color space converter logic having bit-shift logic producing approximations of at least one YCbCr color space component of a pixel represented in RGB color space, the converter logic bit-shifts each RGB color space component and adds or subtracts the bit shifted RGB color space component to an approximation result value of the at least one YCbCr color space component, wherein an approximation of the Y color space component is produced and an approximation of the Cr color space component is produced by the color space converter logic by performing an arithmetic operation on at least two computed Y color space component approximations each shifted by at least one bit, and on at least two R color space components each shifted by at least one bit;
- a histogram generator producing a histogram from one of the color space component approximations of pixels of the image, wherein the histogram generator comprises:
- a plurality of accumulators, each defining exactly one luminance interval spanning a plurality of luminance values;
- first comparator logic determining a frequency of occurrence of pixels in the image having a luminance within each luminance interval;
- second comparator logic identifying a luminance interval with the highest frequency of occurrence;
- and
- background removal logic identifying and setting to a predetermined maximum or white value the red, green and blue components of each pixel in the image having a luminance greater than or equal to a cutoff value (Cutoff) that is a predetermined percentage of the luminance value in the identified luminance interval, wherein the predetermined percentage is at least 80%;
- and
- pixel expansion logic expanding the red, green and blue components of each pixel in the image having a luminance value less than Cutoff.
6 more elements
A method for processing color pixel data of an image, comprising the steps of:
- computing using hardware logic an approximation of one or more YCbCr color space components of a pixel represented in RGB color space, by bit-shifting each RGB color space component and adding or subtracting the bit-shifted RGB color space component to a resulting approximation value of the Y color space component and by computing the Cb color space component approximation by performing an arithmetic operation on at least two computed Y color space component approximations each shifted by at least one bit, and on at least two B color space components each shifted by at least one bit;
- and
- evaluating a characteristic of the pixel in response to the computed approximation of the one or more YCbCr color space components.
A method for processing color pixel data of an image, comprising the steps of:
- computing using hardware logic an approximation of one or more YCbCr color space components of a pixel represented in RGB color space, by bit-shifting each RGB color space component and adding or subtracting the bit-shifted RGB color space component to a resulting approximation value of the one or moreYCbCr color space components;
- and
- evaluating a characteristic of the pixel in response to the computed approximation of the one or more YCbCr color space components, wherein computing an approximation of the Y color space component comprises computing (R>>2)+(G>>1)+(B>>2), where “X>>n” represents shifting the RGB color space component X by n bits;
- wherein computing an approximation of the Cr color space component comprises computing ((R>>1)+(R>>2)−(R>>5))−((Y>>1)+(Y>>2)−(Y>>5)).
1 more element
A method for processing color pixel data of an image, comprising the steps of:
- computing using hardware logic an approximation of one or more YCbCr color space components of a pixel represented in RGB color space, by bit-shifting each RGB color space component and adding or subtracting the bit-shifted RGB color space component to a resulting approximation value of the one or moreYCbCr color space components;
- and
- evaluating a characteristic of the pixel in response to the computed approximation of the one or more YCbCr color space components, wherein computing an approximation of the Y color space component comprises computing (R>>2)+(G>>1)+(B>>2), where “X>>n” represents shifting the RGB color space component X by n bits, wherein computing an approximation of the Cb color space component comprises computing ((B>>1)+(B>>4))−((Y>>1)+(Y>>4)).
A system for processing color pixel data of an image, comprising:
- color space converter logic having bit-shift logic producing approximations of at least one YCbCr color space component of a pixel represented in RGB color space, the converter logic bit-shifts each RGB color space component and adds or subtracts the bit shifted RGB color space component to an approximation result value of the at least one YCbCr color space component, wherein an approximation of the Y color space component is computed by summing an R color space component shifted by two bits, the G color space component shifted by one bit, and the B color space component shifted by two bits;
- and
- a histogram generator producing a histogram from one of the computed color space component approximations of pixels of the image;
- wherein an approximation of the Cb color space component is computed by the color space converter logic by performing an arithmetic operation on at least two computed Y color space component approximates each shifted by at least one bit, and on at least two B color space components each shifted by at least one bit.
1 more element
Dependencies are inferred from the claim text.