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US 9,195,160 B2Granted
Image forming apparatus and image forming method for correcting registration deviation
AssigneeCanon Kabushiki Kaisha
InventorSeijiro Morita
Life of this patent
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Abstract
Since memory access is performed on a large number or discontinuous address regions, the performance of memory access is significantly degraded; in a system that performs high speed image formation, registration deviation cannot be corrected. Sub scanning position information corresponding to the profile of registration deviation is set, and image correction processing is divided into two stages, high resolution correction processing using line buffers formed with a memory which allows high speed random access and low resolution correction processing using a memory whose capacity is easily increased.
Claims15
An image forming apparatus including an image forming unit, comprising:
- an obtaining component configured to obtain shift amounts in a sub scanning direction of a scanning line formed by the image forming unit at respective positions in a main scanning direction for an image which includes pixels, each of the shift amounts at the respective positions including a first shift amount equivalent to a first number of pixels and a second shift amount equivalent to a second number of pixels, wherein the first number of pixels corresponds to an integer less than a predetermined number of pixels for a predetermined resolution, and the second number of pixels corresponds to a multiple of the predetermined number of pixels for the predetermined resolution;
- a first correction component configured to correct the image by shifting, in the sub scanning direction, a pixel included in the image at each of the positions in the main scanning direction on a basis of the first shift amount to write the shifted pixel to a corresponding address in a memory;
- and
- a second correction component configured to correct the image corrected by the first correction component, by shifting a read address in the sub scanning direction in the memory at a corresponding position among the respective positions in the main scanning direction, at which the second shift amount shifts, on a basis of the second shift amount and reading out, by continuous address access in the main scanning direction in a unit which is determined based on the second shift amount, pixels stored in addresses continuous in the main scanning direction in the memory.
1 more element
An image processing apparatus comprising:
- a first memory configured to store an image including pixels;
- an obtaining component configured to obtain shift amounts of sub scanning position of pixels at respective main scanning positions of the image, each of the shift amounts of sub scanning position being sum of a first shift amount and a second shift amount, wherein the first shift amount corresponds to less than a fixed number of pixels, the second shift amount corresponds to a multiple of the fixed number of pixels;
- a first correction component configured to store the image in the first memory into a second memory, and to output pixels from the second memory sequentially, whose sub scanning positions at the respective main scanning positions in the second memory is determined based on respective first shift amounts, to respective continuous addresses in a third memory as much as number of pixels corresponding to one main scanning line, so that sub scanning positions of pixels at continuous main scanning positions in the second memory, where respective second shift amounts are equivalent, are shifted by the respective first shift amounts to store the pixels to continuous addresses in the third memory;
- and
- a second correction component configured to read out, by continuous address access in a unit which is determined based on the respective second shift amounts, the pixels corresponding to one main scanning line sequentially output in the third memory, so that the sub scanning positions of the pixels at the continuous main scanning positions in the third memory, where the respective second shift amounts are equivalent, are shifted by the respective second shift amounts.
2 more elements
An image processing method using a first memory, a second memory and a third memory, comprising:
- obtaining shift amounts in a sub scanning direction at respective main scanning positions of an image in the first memory, each of the shift amounts being sum of a first shift amount and a second shift amount, wherein the first shift amount corresponds to less than a first predetermined lines, and the second shift amount corresponds to a multiple of the first predetermined lines;
- and
- repeating following (i), (ii) and (iii) so that the third memory stores part of the image corresponding to a second predetermined lines, wherein the number of the second predetermined lines is larger than the first predetermined lines:
- (i) storing to the second memory, among the image in the first memory, an image within a processing window consist of the number of first predetermined lines;
- (ii) outputting pixels one by one at the respective main scanning positions from the first predetermined lines in the second memory to continuous addresses of one line as a output destination line in the third memory based on the respective first shift amounts;
- and
- (iii) shifting the processing window and the output destination line in the sub scanning direction by one line;
- and
- reading out pixels one by one at the respective main scanning positions from the second predetermined lines in the third memory by continuous address access in the main scanning direction in a unit which is determined based on the respective second shift amounts, to output the read out pixels as one line.
6 more elements
Dependencies are inferred from the claim text.