Image analysis – Image compression or coding – Adaptive coding
Reexamination Certificate
1992-04-22
2001-05-22
Chang, Jon (Department: 2623)
Image analysis
Image compression or coding
Adaptive coding
C382S244000, C382S248000, C358S001150, C358S001170
Reexamination Certificate
active
06236755
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an output method and apparatus for outputting an image in accordance with data input from an external apparatus, such as a host computer or the like.
2. Description of the Related Art
FIG. 2
is a block diagram showing the flow of processing in a control unit
1
of a conventional output apparatus such as a printing apparatus.
In
FIG. 2
, an external apparatus
2
outputs print data from a host computer or the like. An input unit
3
receives the data. An analyzing unit
4
analyzes input data. A developing unit
5
develops data into an output image, for example, in the form of a bit-map memory according to analysis of the analyzing unit
4
. A frame memory
6
stores the developed output image, and comprises a RAM (random access memory). An output unit
7
controls an output mechanism
8
, such as a laser-beam printer or the like, in accordance with the data stored in the frame memory
6
so as to cause the output mechanism
8
to output the data onto recording medium
9
such as paper or the like.
In the control unit
1
, print data output from the external apparatus
2
are received by the input unit
3
, and are analyzed by the analyzing unit
4
. According to the result of the analysis, the developing unit
5
forms an output image, for example, in the form of a binary bit-map memory for one page in the frame memory
6
. The output unit
7
performs, for example, on/off control of a laser beam for the output mechanism
8
in accordance with the data stored in the frame memory
6
, whereby a print result is recorded on the recording medium
9
.
Because of the large memory capacity needed for frame memory
6
, such a conventional approach is not satisfactory. Specifically, since data are stored in the frame memory
6
in the form of a bit-map memory or the like which is convenient for development, a very large capacity is needed for the frame memory
6
. For example, if the user desires to develop a black-and-white A4-size image with a resolution of 600 dpi (dots per inch), a binary bit-map memory with a capacity of about 4 megabytes is needed for one page. In order to deal with a multivalue output or a color output, a binary bit-map memory with a capacity of several times the above-described value is needed.
SUMMARY OF THE INVENTION
The present invention has been made in order to solve the above-described problems.
It is An object of the present invention to provide an output apparatus for outputting data after developing an output image in a memory, for example, in the form of a bit map or the like. The apparatus comprises means for controlling a memory for developing an image, for example, in the form of a bit map or the like by dividing the memory, means for developing an output image in the divided memory, means for compressing data stored in the divided memory, means for performing recompression by changing to a more-efficient method of compression when the compression ratio in the compression is insufficient, storage means for storing the divided compressed memory, storage means for storing methods of compression for respective compressed portions, and means for expanding the compressed memory to the original divided part.
It is another object of the present invention to provide an output method and apparatus, wherein a memory stores data to be developed that is compressed and divided into a plurality of portions, methods of compression for respective divided portions are stored, recompression is performed by changing to a more-efficient method of compression when the compression ratio is insufficient, the recompressed portion is stored in a small-capacity memory, only a portion necessary for development is taken out while being expanded whenever necessary, the taken-out portion is developed and expanded for output while portions not to be developed are stored in compressed form.
It is still another object of the present invention to provide an output method and apparatus, wherein a memory for development is stored while being divided and compressed, and only a necessary portion is utilized while being expanded when the portion is developed and output, whereby the capacity of the memory can be greatly reduced.
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Canon Kabushiki Kaisha
Chang Jon
Fitzpatrick ,Cella, Harper & Scinto
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