US 5,208,874 AGranted

Method for correcting image signal deteriorated by flare and image reading unit

AssigneeRicoh Company, Ltd.

InventorKatsuyuki Omura

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Abstract

A method for correcting image information deteriorated by flare generated in an image reading unit having a light source for irradiating a document, a scanning system optically scanning the document irradiated by the light source and outputting the image information, and a reference image having a predetermined density distribution is provided. The method includes the following steps of: optically scanning the reference image irradiated by the light source, the scanning system outputting reference image information corresponding to the reference image; generating a function denoting a response with respect to the deterioration of the image information caused by the flare based on the reference image information obtained by the scanning system; optically scanning the document irradiated by the light source by the scanning system; and performing a deconvolution operation in which the image information obtained by the scanning system and the above function are used.

Claims8

Dependent claims

A method for correcting image information deteriorated by flare generated in an image reading unit having a light source for irradiating a document, a scanning system for optically scanning the document irradiated by said light source line by line and outputting the image information, and a reference image having a step shaped density distribution in a direction parallel to each scanning line of said scanning system, said method comprising the following steps (a) through (d) of:

(a) optically scanning, with said scanning system, the reference image having a step shaped density distribution irradiated by said light source, and said scanning system outputting reference image information corresponding to the reference image;
(b) generating a function representing an effect surrounding points have on the density of a specified point, said effect being caused by the flare, using the reference image information obtained by said scanning system in said step (a);
(c) optically scanning the document irradiated by said light source with said scanning system, such that said scanning system outputs image information of the document;
and
(d) performing a deconvolution operation in which the image information of the document outputted by said scanning system in said step (c) and the function generated by said step (b) are used to calculate corrected image information of the document.

2 more elements

An image reading unit comprising:

a light source for irradiating a document;
a scanning system for optically scanning the document irradiated by said light source line by line and outputting image information of the document;
a reference image having a step shaped density distribution in a direction parallel to scanning lines of said scanning system;
generating means for generating a function, which represents an effect surrounding points have on a density of a specified point, said effect being caused by flare, using reference image information obtained by using said scanning system to optically scan said reference image irradiated by said light source;
and
deconvolution means for performing a deconvolution operation in which the image information of the document and the function generated by said generating means are deconvoluted to obtain corrected image information.

3 more elements

Dependencies are inferred from the claim text.