Image processing apparatus for processing a bi-level image and method therefor
AssigneeOki Data Corporation
InventorsLiming Chen, Osamu Asada
Life of this patent
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Abstract
A bi-level image is pre-processed by dividing the image into rectangular blocks, and rearranging the dots in each rectangular block into a pattern determined by the density of black dots in the block. The resulting rearranged image is suitable for further processing such as resolution conversion or compressive encoding.
Claims9
An image processing apparatus for processing a bi-level image formed by dots having a first value and dots having a second value, comprising:
- an image regularizer dividing said bi-level image into rectangular blocks of a predetermined number of dot locations, counting the number of dots having the first value in each rectangular block among said rectangular blocks, rearranging the dots in said rectangular block into a predetermined pattern determined by the number of dots having said first value in said rectangular block, thereby producing a rearranged image, wherein said predetermined pattern is a spiral pattern beginning at a central dot location in said rectangular block, the number of dots having the first value in said spiral pattern is the same as the number of dots having the first value in said rectangular block before the dots are rearranged, and the number of dots having the second value in said spiral pattern is the same as the number of dots having the second value in said rectangular block before the dots are rearranged.
An image processing apparatus for processing a bi-level image formed by dots having a first value and dots having a second value, comprising:
- an image regularizer dividing said bi-level image into rectangular blocks of a predetermined number of dot locations, and in each of said rectangular blocks, rearranging the dots into a predetermined pattern determined by how many dots have said first value in said rectangular block, thereby producing a rearranged image;
- a first encoder for compressively encoding said rearranged image, thereby obtaining first coded data;
- a second encoder for compressively encoding said bilevel image, thereby obtaining second coded data;
- a code size counter coupled to said second encoder, for determining a size of said second coded data;
- a comparator coupled to said code size counter, for comparing said size with a threshold value;
- and
- a selector coupled to said comparator, for selecting said first coded data when said size exceeds said threshold value, and selecting said second coded data when said size does not exceed said threshold value, the coded data selected by said selector being used as output data of said apparatus.
A method of converting a bi-level image, formed by dots having a first value and dots having a second value, from a first resolution to a second resolution, comprising the steps of:
- dividing said bi-level image into rectangular blocks of a predetermined number of dot locations;
- counting the dots having said first value in each of said rectangular blocks, thereby obtaining a density count for each of said rectangular blocks;
- rearranging the dots in each rectangular block into a predetermined pattern determined by the density count of said rectangular block, thereby generating a rearranged image having said first resolution, wherein said predetermined pattern is a spiral pattern beginning at a central dot location in said rectangular block, the number of dots having the first value in said spiral pattern is the same as the number of dots having the first value in said rectangular block before the dots are rearranged, and the number of dots having the second value in said spiral pattern is the same as the number of dots having the second value in said rectangular block before the dots are rearranged;
- and
- converting said rearranged image from said first resolution to said second resolution.
Dependencies are inferred from the claim text.