Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
1998-11-24
2001-12-11
Lee, Thomas D. (Department: 2724)
Facsimile and static presentation processing
Static presentation processing
Attribute control
C382S239000
Reexamination Certificate
active
06330077
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus for forming a dot image corresponding to a dot pattern based on the image data.
BACKGROUND OF THE INVENTION
An image forming apparatus for forming a dot image is generally applied in a dot-image output device such as a laser-beam printer and a CRT. For example, the laser-beam printer employs an image exposing system or a background exposing system for forming a dot image by providing ON/OFF controls to laser beams according to inputted bitmap data.
A diameter of the dot is maintained substantially constant at a specified value according to a period of laser-beam emission or according to the power of light during formation of a dot image. Then, generally, the dot image is subjected to smoothing processing according to the type of the dot image or according to the resolution when recording is executed.
In the conventional type of image forming apparatus described above, in addition to maintaining a dot diameter constant at a specified value regardless of a type of an output image, since many cases where characters are reproduced as an output image, a larger diameter of a dot suitable for reproduction of characters has been employed. For this reason, when an output image is characters, an optimal dot image for the above purpose can be formed. However, when an output image is an image or a dot image with open characters or the like, a portion with white dots existing between black dots is compressed according to a distance between the dots due to characteristics specific to an output image, which makes reproducibility of image quality lower.
This type of problem occurs not only in printing with the dot-image output device such as a laser-beam printer, but also in displaying with the dot-image output device such as a CRT.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide, for solving the problems described above, an image forming apparatus that can improve reproducibility of image quality according to characteristics of an output image.
With the present invention, a correlation between each dot diameter and each position of remarked dots to be varied for each dot pattern is previously stored, and when a dot pattern matching a dot pattern based on inputted dot image data is detected, a dot diameter corresponding to the position of the remarked dot in the dot pattern is varied and corrected, so that a dot image appropriate for a dot pattern can be formed, and with this feature, it is possible to improve reproducibility of image quality according to characteristics of an output image.
With the present invention, a dot diameter is varied and corrected in each dot pattern in which a single remarked dot or remarked dots aligned in any of horizontal, vertical or diagonal directions are surrounded by dots having a different color or gray scale from that of remarked dot or dots, and in which between first and second lines of remarked dots have at least three or more lines with dots having a different color or gray scale from that of the remarked dots, so that it is possible to reproduce a point of a remarked dot and a line with remarked dots so that the point and the line can be recognized without being filled up by the surrounding dots having a different color or gray scale, and appropriately maintain the density of the image pattern.
With the present invention, an output dot image is formed by performing pulse width modulation, output current modulation or both to the dot image data in which the dot diameter has been varied and corrected, so that it is possible to realize image formation optimal to an output mode.
With the present invention, when a dot pattern matching that in dot pattern groups each having a different priority is detected in the inputted dot image data, dot image data corrected by using the highest priority dot pattern group is selected and outputted, so that optimal correction can be performed as required according to the state of the input dot image, and with this feature, it is possible to preferentially improve image quality of an outside shape.
With the present invention, when a matching dot pattern is not detected, each dot diameter based on the inputted dot image data is corrected to the default size, and the corrected dot image data is selected and outputted, so that any input dot image having no specified dot pattern can even be subjected to a minimum default correction, and with this feature, it is possible to improve image quality of an outside shape even in any of input dot images.
With the present invention, a dot diameter is varied and corrected in each dot pattern in which a single remarked dot or remarked dots aligned in any of horizontal, vertical or diagonal directions are surrounded by dots having a different color or gray scale from that of remarked dot or dots, and in which between first and second lines of remarked dots have at least three or more lines with dots having a different color from that of the remarked dots, so that it is possible to reproduce a point of a remarked dot and a line with remarked dots so that the point and the line can be recognized without being filled up by surrounding dots having a different color or gray scale, and appropriately maintain the density of the image patterns.
With the present invention, an output dot image is formed by performing pulse width modulation, output current modulation or both to the selected and outputted dot image data, so that it is possible to realize image formation optimal to an output mode.
With the present invention, when a dot pattern based on inputted dot image data requires both of smoothing processing and emphasizing processing, the smoothing processing is preferentially outputted over the emphasizing processing, so that optimal correction can be performed as required according to the state of input dot image, and with this feature, it is possible to preferentially improve the image quality of an outside shape.
With the present invention, when corresponding dot pattern is not detected, dot diameter based on inputted dot image data is corrected to the default size, and the corrected dot image data is selected and outputted, so that any input dot image having a dot pattern not required to be subjected to smoothing processing or emphasizing processing can even be subjected to minimum default correction, and with this feature, it is possible to improve the image quality of an outside shape even in any of input dot images.
Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings.
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Horie Hiromitsu
Kamata Takao
Sasaki Eiji
Sato Kazuhiko
Armstrong, Westerman, Hattori, McLeland & Naughton, LLP.
Brinich Stephen
Fujitsu Limited
Lee Thomas D.
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