Image reading apparatus having aberration correction function

An image reading device and aberration technology, applied in image communication, electrical components, etc., can solve problems such as large distortion changes

CN103826030AInactive Publication Date: 2014-05-28JAI
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2014-05-28
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention relates to an image reading apparatus having an aberration correction function, which can correct color migration generated by a chromatic aberration and distortion aberration caused by an optical element through a digital filter in only one direction in a condition without using a switch for switching. An aberration correction unit has a digital filter group, a delay control unit, and a memory. The digital filter group take one of multiple colored lights controlled through a delay time caused of the aberration of the optical element of each read image of a line image sensor as a benchmark colored light and the rest colored lights are treated as other colored lights, and are disposed on the rest colored lights. The delay control unit, based on a calculation value of each delay amount between formed images of the benchmark colored light and other colored lights, controls a filter coefficient of the digital filter group. The delay control unit, when a picture transverse width of other colored lights gets wider with respect to a picture transverse width of the benchmark colored light, in a state of reading image positions of scanning finishing ends of the bench colored light and other colored lights, begins to read, from scanning beginning end formed images of the other colored lights, the calculation value of each delay amount which takes a scanning beginning end formed image of the benchmark colored light as a benchmark, controls the filter coefficient of the digital filter group, and thus the color migration generated by the aberration of the optical element can be corrected.
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Description

technical field

[0001] The present invention relates to an image reading device having an aberration correction function that corrects aberrations caused by an optical element that forms a read image of a document or the like. Background technique

[0002] There are aberrations in a lens that is an optical element that forms a read image of a document or the like, and one of the chromatic aberrations is caused by a slightly different refractive index of glass (dispersion) depending on the wavelength.

[0003] This appears as axial chromatic aberration and lateral chromatic aberration, and when three line image sensors are used for color, they need to be arranged at imaging point positions matching the respective wavelengths of RGB.

[0004] In addition, the above-mentioned aberrations are all aberrations related to smudges, imaging positions, and image size of the imaged image, but there are also distortion aberrations as aberrations related to distortion of the overall imag...

Examples

Embodiment 1

[0097] Embodiment 1 of the present invention is an image reading device having an aberration correction function in which, in the aberration distortion of an image such as lateral chromatic aberration caused by an optical element and color shift caused by distortion aberration, based on the reference The measured value of each delay between the imaging image of one color light and the imaging image of other color light, aberration distortion caused by barrel distortion or pincushion distortion caused by optical elements from the scanning start end of the screen to the center position and from the screen The opposite lead / lag is generated from the central position to the end of scanning, and further, in addition to the opposite aberration distortion, by controlling the delay in only one direction with a digital filter bank, it is also possible to correct the magnification color caused by the optical element Aberration is the color shift between the reference color light image an...

Embodiment 2

[0152] Embodiment 2 of the present invention is an image reading device with an aberration correction function, which electrically compares the pixel readout clock with accurate time intervals and no distortion with the W (RGB) image signal of the reference color light or each color light of other color lights. The aberration distortion of the W image signal generated by the chromatic aberration or the distortion aberration caused by the optical element is corrected, and the RGB image signal without aberration distortion can be obtained.

[0153] exist Figure 4 in figure 1 In the circuit block diagram of the first embodiment, a digital filter bank 22 for G is added.

[0154] according to Figure 4 ~ Figure 6 A calculation method for aberration correction due to barrel distortion, pincushion distortion, and lateral aberration in Embodiment 2 of the image reading device 1 having an aberration correction function will be described.

[0155] In addition, the basic structure a...