Source: http://patents.com/us-7751616.html
Timestamp: 2019-01-22 08:10:04
Document Index: 596357887

Matched Legal Cases: ['art 530', 'arts 532', 'art 532', 'art 532', 'art 532', 'art 532', 'art 534', 'art 536', 'art 538', 'art 540', 'arts 532', 'art 536', 'arts 532', 'art 536', 'art 536', 'arts 532', 'art 532', 'art 534', 'art 532', 'arts 532', 'art 532', 'arts 532', 'art 510']

US Patent # 7,751,616. Coding apparatus and method and storage medium storing program - Patents.com
United States Patent 7,751,616
Yokose , et al. July 6, 2010
A coding apparatus includes a color space conversion unit that converts input image data into image data which is represented in another color space, a gradation changing unit that changes gradation of the input image data, based on the converted image data, and a predictive coding unit that performs predictive coding on the image data subjected to the gradation change.
Inventors: Yokose; Taro (Nakai-machi, JP), Sekino; Masanori (Nakai-machi, JP)
Appl. No.: 11/236,789
Mar 23, 2005 [JP] 2005-083506
Current U.S. Class: 382/166 ; 382/238
5990864 November 1999 DeAguiar et al.
7035459 April 2006 Ishiga
7130462 October 2006 Nakami
7212680 May 2007 Shin
7409083 August 2008 Yano
2005/0063587 March 2005 Nishiwaki et al.
Gregory Baxes, "Lossless Predictive Coding", in Digital Image Processing, John Wiley & Sons, Inc., 1994. cited by examiner.
1. A coding apparatus comprising: a memory; and a controller including: a color space conversion unit that converts input image data into image data which is represented in another color space, the input image data including a gradation value, the converted input image data being composed of a luminance or lightness component and other color components; a gradation changing unit that changes the gradation value of the input image data, based on the converted image data; and a predictive coding unit that performs predictive coding on the image data subjected to the gradation value change, wherein the gradation changing unit determines whether to change the gradation value of the input image data, based on the image data converted by the color space conversion unit, and the gradation changing unit calculates a difference between a pixel value of a pixel of the converted image data and a predicted pixel value of the pixel of the converted image data for each color component, and compares the difference with a tolerance set for each color component to determine whether to change the gradation value of the input image data.
3. The coding apparatus according to claim 2, further comprising: a color space reconversion unit that converts the image data subjected to the gradation value change into image data represented in the same color space as for the input image data.
4. The coding apparatus according to claim 3, wherein the input image data is represented in an RGB color space, the color space conversion unit converts the input image data into the image data represented in another color space, and the color space reconversion unit converts the image data subjected to the gradation value change by the gradation changing unit into image data represented in the RGB color space.
7. A coding method comprising: converting, by a controller, input image data to image data which is represented in another color space, the input image data including a gradation value, the converted input image data being composed of a luminance or lightness component and other color components; determining, by the controller, if changing the gradation value of the input image data is permitted based on comparing a calculated a difference between a pixel value of a pixel of the converted image data and a predicted pixel value of the pixel of the converted image data for each color component with a tolerance set for each color component; changing, by the controller, the gradation value of the input image data when changing the gradation value is permitted, based on the converted image data; and performing, by the controller, predictive coding on the image data subjected to the gradation value change.
9. A non-transitory storage medium readable by a computer, the storage medium storing a program comprising instructions causing a computer to execute a function comprising: converting input image data to image data which is represented in another color space, the input image data including a gradation value, the converted input image data being composed of a luminance or lightness component and other color components; determining if changing the gradation value of the input image data is permitted based on comparing a calculated a difference between a pixel value of a pixel of the converted image data and a predicted pixel value of the pixel of the converted image data for each color component with a tolerance set for each color component; changing the gradation value of the input image data when changing the gradation value is permitted, based on the converted image data; and performing predictive coding on the image data subjected to the gradation value change.
10. The storage medium according to claim 9, wherein the other color components include chrominance components.
The present invention has been made in view of the foregoing background and provides a coding apparatus that achieves a high compression rate, while suppressing image quality deterioration.
To help understanding of the present invention, its background and overview will first be described.
As illustrated in FIG. 5, the predictive coding part 530 includes plural prediction parts 532 (a first prediction part 532a, a second prediction part 532b, a third prediction part 532c, and a fourth prediction part 532b), a prediction error calculation part 534, a run counting part 536, a selecting part 538, and a code generating part 540.
Each of the prediction parts 532 in this example refers to the pixel values of a pixel (one of reference pixels) different from the pixel of interest, takes the pixel values as predicted values, and outputs the result of the comparison between the predicted value data and the pixel value data of the pixel of interest to the run counting part 536. More specifically, the first to fourth prediction parts 532a to 532d respectively compare the pixel values of reference pixels A to D (which will be described later with reference to FIG. 6A) to the pixel value data of the pixel X of interest (which will be described later with reference to FIG. 6A). As a result, if pixel value data matching occurs (i.e., a prediction hit occurs), each prediction part outputs its prediction part ID which identifies itself to the run counting part 536. Otherwise, each prediction part outputs a mismatch result to the run counting part 536. Although the plural prediction parts 532 are employed in this example, there may be provided at least one prediction part, for example, only the first prediction part 532a which makes reference to the reference position A.
The prediction error calculation part 534 in this example takes the pixel values of the pixel (reference pixel A) in the same reference position as for the first prediction part 532a as predicted values and calculates differences between the predicted values and actual pixel values (of the pixel X of interest).
As illustrated in FIG. 6A, the pixels that are respectively referred to by the plural prediction parts 532 are positioned relatively to the pixel X of interest. Specifically, the reference pixel A for the first prediction part 532a is positioned at an upstream side (the left) of the pixel X of interest in the fast-scan direction. The reference pixels B to D for the second to fourth prediction parts 532b to 532d are positioned one fast-scan line above the pixel X of interest (upstream in the slow-scan direction).
Next, a first example of modification to the foregoing embodiment will be described.
Next, a second modification example will be described.
The filter processing part 510 (FIG. 2) in the foregoing embodiment determines whether the differences between the pixel values of the pixel of interest and the predicted values fall within the tolerances for each color component and changes the pixel values of the pixel of interest, according to the result of the decision. However, the coding process of the present invention is not limited so. For instance, it is possible to change the pixel values of the pixel of interest without determining whether the differences between the pixel values of the pixel of interest and the predicted values fall within the tolerances.
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