Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
1998-09-28
2001-08-14
Lee, Thomas D. (Department: 2724)
Facsimile and static presentation processing
Static presentation processing
Attribute control
C382S237000
Reexamination Certificate
active
06275303
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing method and an image processing system wherein a combination of images including various types of color or halftone images, such as graphic images, continuous tone images, text and so on, is converted into a binary bitmap image by using halftoning techniques.
2. Description of the Related Art
When a combination of images including text, graphic images and continuous tone images is printed by a printer, the combination of images is converted into a binary bitmap image. If the combination of images includes halftone images or color images, halftoning techniques are used for the conversions of them.
Text and graphic images are generated by personal computers or word processors. The text and the graphic images are written in page description language. When the text and the graphic images are printed by the printer, they are converted into multi-level tone value images, each pixel of which has a multi-level tone value, such as a value that ranges between 0 and 255 (i.e., 8 bits value). Further, the multi-level tone value images are converted into the binary bitmap images by using a simple halftoning technique, such as an ordered dither method, a dot pattern method, or the like.
On the other hand, continuous tone images, such as photographs, are scanned by an image scanner and stored into a memory device of a personal computer. When the continuous tone images are printed by the printer, they are converted into binary bitmap images by using a halftoning technique that is different from the halftoning technique used for the conversion of text and graphic images. In case of continuous tone images, an error diffusion method or a minimum average error method is used for the purpose of increasing the quality of reproduction of continuous tone images.
Therefore, when a combination of images including color or halftone graphic images, continuous tone images and text is printed by the printer, it is converted into a binary bitmap image by using at least two kinds of halftone technique, depending on whether each image is graphic image, continuous tone image or text.
A dither pattern is used in the dithering process. The properties of the dither pattern affect tone and resolution of a binary bitmap image generated in the dithering process. If the user can selects a suitable dither pattern from among various dither patterns, it is possible to increase the quality of the binary bitmap image.
However, if the dither pattern is changed, the text and the graphic images have to be converted again into the multi-level tone value images, and the multi-level tone value images have to be further converted again into the binary bitmap images. And also, the continuous tone images have to be converted again into the binary bitmap images. Thus, each time the dither pattern is changed, the converting process wherein text and graphic images are converted into multi-level tone value images, the converting process wherein the multi-level tone value images are converted into binary bitmap images, and the converting process wherein continuous tone images are converted into binary bitmap images have to be performed again, regardless of that the original text, graphic images and continuous tone images are not changed. As a result, each time the dither pattern is changed, it takes a long time for the converting processes.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an image processing method and an image processing system which can quickly convert a combination of text, graphic images and continuous tone images into a binary bitmap image when a dither pattern is changed.
According to the present invention, the above mentioned object can be achieved by an image processing method of binarizing a plurality of multi-level tone value images including at least a first multilevel tone value image and a second multi-level tone value image, the image processing method having the processes of: converting the first multi-level tone value image into a first bitmap image consisting of binary values; replacing each binary value of the first bitmap image representing an on condition by a maximum value in a tone value range of the second multi-level tone value image and replacing each binary value of the first bitmap image representing an off condition by a minimum value in the tone value range of the second multi-level tone value image; managing the first bitmap image, whose each binary value has been replaced in the replacing process, and the second multi-level tone value image as a single intermediate image; converting the intermediate image into a second bitmap image consisting of binary values, by using a threshold data matrix; and outputting the second bitmap image.
The first multi-level tone value image is converted into the first bitmap image. The first bitmap image consists of a plurality of binary values (i.e., dots) each representing either an on condition or an off condition.
Next, the first bitmap image is further converted in the following manner. Namely, each binary value of the first bitmap image representing the on condition is replaced by the maximum value in the tone value range of the second multi-level tone value image, and each binary value of the first bitmap image representing the off condition is replaced by the minimum value in the tone value range of the second multi-level tone value image. Thus, the value range of each value of the first bitmap image is the same as that of the second multi-level tone value image.
After this process, the first bitmap image and the second multi-level tone value image are managed as a single intermediate image.
Next, the intermediate image is converted into a second bitmap image consisting of binary values, by using the threshold data matrix. Next, the second bitmap image is outputted.
As every value of the intermediate image (i.e., the first bitmap image and the second multi-level tone value image) is in the same value range, the intermediate image can be converted into the second bitmap image by only one kind of converting process. Therefore, the intermediate image can be converted in a short time.
When the intermediate image is converted into the second bitmap image, the threshold data matrix may be changed to a different threshold data matrix for the purpose of, for example, changing tone and resolution of the second bitmap image. If the threshold data matrix is changed, the new second bitmap image can be quickly generated because it can be generated by using the intermediate image which has been previously generated. Namely, the new second bitmap image can be generated by only converting the intermediate image by using the different threshold data matrix. It is not required to generate intermediate image again. Therefore, it is possible to quickly generate the second bitmap image by using various threshold matrix.
According to the present invention, the above mentioned object can be also achieved by an image processing system for binarizing a plurality of multi-level tone value images including at least a first multi-level tone value image and a second multi-level tone value image, the image processing system having: a first converting device for converting the first multi-level tone value image into a first bitmap image consisting of binary values; a replacing device for replacing each binary value of the first bitmap image representing an on condition by a maximum value in a tone value range of the second multi-level tone value image and replacing each binary value of the first bitmap image representing an off condition by a minimum value in the tone value range of the second multi-level tone value image; a storage device for storing the first bitmap image, whose each binary value has been replaced by the maximum value or the minimum value in the tone value range of the second multi-level tone value image, and the second multi-level tone value image as a single intermediate image; a second converting device for convertin
Brinich Stephen
Brother Kogyo Kabushiki Kaisha
Lee Thomas D.
Oliff & Berridg,e PLC
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