Image analysis – Image compression or coding – Quantization
Reexamination Certificate
1997-12-04
2001-08-28
Boudreau, Leo (Department: 2621)
Image analysis
Image compression or coding
Quantization
C382S156000, C382S253000, C358S001900, C358S451000
Reexamination Certificate
active
06282323
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing method and apparatus for quantizing input image data into data having levels which are smaller in number than input levels of the input image data and, more particularly, to an image processing method and apparatus for performing a quantizing process such that image data is adapted to an output device in which an output area of one pixel changes depending on the position of the pixel.
2. Description of the Related Art
In order to reproduce a variable-density image by a printer or a display which performs a binary display by black and white, an area gradation method which expresses the variable-density image by forming a pseudo digital half-tone image has been conventionally used. The area gradation method is a method for changing the ratio of black in a neighborhood image to reproduce a gradation image. As this method, a dither method in which a variable-density image u(x,y) of an original image is compared with a threshold value T calculated by a predetermined rule or an error diffusion method in which an error between an input variable-density image value and an output half-tone image is diffused to a pixel which is not scanned is practically used.
In a color image, the following technique is conventionally known. That is, an input color image is subjected to a half-tone process by using the dither method or the error diffusion method to obtain low-bit data (e.g., 1-bit binary data), and a full-color image is formed by using a binary printer and a binary display device.
However, the conventional dither method or the conventional error diffusion method is designed on the assumption that an output device has the same gradation expression capability for all pixels (all the pixels have the same maximum luminance, the same number of bits, and the same color expression capability). For this reason, each of these method has a drawback that an output device which has different maximum luminances, the different numbers of bits, and different color expression capabilities for respective pixels cannot be used. In addition, in a device such as a liquid-crystal display in which the number of pixels is fixed, when the number of pixels of display data and the number of pixels of the device are different from each other, a half-tone process must be performed after resolution conversion is performed by an interpolation process.
SUMMARY OF THE INVENTION
The present invention has been made to remove the drawback of the prior art, and has as its object to provide an image processing method and apparatus in which quantized data (data subjected to a half-tone process) to be output to an output device which has different maximum luminances, the different number of bits, different color expression capabilities, and different resolutions for respective pixels on the basis of input multi-value image data.
It is another object of the present invention to provide an image processing method and apparatus which can perform an optimum half-tone process by an algorithm based on a cellular neural network even if pixels have different maximum luminances, the different numbers of bits, and different color expression capabilities and can obtain a high-quality image.
It is still another object of the present invention to provide an image processing method and apparatus which can perform a half-tone process in a standard resolution mode and a high-resolution mote by updating a table and the value of a memory in the same hardware.
It is still another object of the present invention to provide an image processing method and apparatus in which an arithmetic operation for a sum of products required for a half-tone process can be performed by only an addition such that data is divided for respective sub-pixels to store the divided data in a memory in advance, and a process speed can be made high.
The above object and other objects will be apparent from the detailed description based on the following drawings.
REFERENCES:
patent: 5488673 (1996-01-01), Katayama et al.
patent: 5608821 (1997-03-01), Metcalfe et al.
patent: 5621542 (1997-04-01), Ohta et al.
patent: 5638190 (1997-06-01), Geist
patent: 5721544 (1998-02-01), Suzuki
patent: 5724090 (1998-03-01), Tanaka et al.
patent: 5768438 (1998-06-01), Etoh
patent: 5805738 (1998-09-01), Kaburagi et al.
patent: 5841904 (1998-11-01), Sugiura
patent: 5867593 (1999-02-01), Fukuda et al.
patent: 5931960 (1999-08-01), Kletter
patent: 5940541 (1999-08-01), Donelly
patent: 6148101 (2000-11-01), Tanaka et al.
Imaizumi Masaaki
Inoue Hiroshi
Ohshima Masamichi
Shingu Toshiaki
Tanaka Mamoru
Boudreau Leo
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Sherali Ishrat
LandOfFree
Image processing method and apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image processing method and apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image processing method and apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2539765