Image correction device and method, and image reading apparatus

• US 8,902,468 B2
• Filed: 01/15/2013
• Issued: 12/02/2014
• Est. Priority Date: 03/29/2012
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Shimizu, Masayoshi
• Primary Examiner(s): Nguyen, Madelein A
• Application Number:
  US13/741,487
• Publication Number:
  US 20130258428A1
• Time in Patent Office: 686 Days
• Field of Search: None
• US Class Current: 358/1.9
• CPC Class Codes: H04N 1/6041 for controlling uniformity of color across image area
• CPC Class Codes: H04N 1/6083 controlled by factors external to the apparatus

Abstract

An image correction device includes a processor that executes a procedure. The procedure includes: correcting an image of a read object based on images stored in a storage section of a self-illuminated reference chart image of a reference chart of size corresponding to a mounting region where the read object is mounted that has been read in advance in a state illuminated by only a self-illumination light, a uniform light standard color chart image of a standard color chart that has been read in advance in a state illuminated by only uniform light from a predetermined uniform light source, and a uniform light reference chart image of the reference chart that has been read in advance in a state illuminated by only the uniform light, and based on the image of the read object and a peripheral light standard color chart image read by a reading section.

Claims

1. An image correction device comprising:

a processor; and

a memory storing instructions, which when executed by the processor perform a procedure, the procedure including;

(a) controlling an image reading apparatus including an illumination section that illuminates self-illumination light from a first light source onto a read object in a state in which peripheral light from a second light source different than the first light source is being illuminated from a periphery of the read object onto the read object, a standard color chart that is provided in an illuminated region illuminated by the self-illumination light and outside of a mounting region where the read object is mounted, a reading section that reads an image of the read object and reads an image of the standard color chart, and a storage section that stores a self-illuminated reference chart image of a reference chart of size corresponding to the mounting region that has been read in advance by the reading section in a state illuminated by only the self-illumination light, that stores a uniform light standard color chart image of the standard color chart that has been read in advance by the reading section in a state illuminated by only uniform light from a predetermined uniform light source that illuminates light uniformly on a whole region of the standard color chart and the reference chart, and that stores a uniform light reference chart image of the reference chart that has been read in advance by the reading section in a state illuminated by only the uniform light, by controlling the illumination section of the image reading apparatus and the reading section such that an image of the read object is read in a state illuminated by combined light in which the peripheral light and the self-illumination light are combined, and such that a peripheral light standard color chart image of the standard color chart is read in a state illuminated by only the peripheral light when the illumination section is off and peripheral light is illuminated; and

(b) correcting the image of the read object based on the self-illuminated reference chart image, the uniform light standard color chart image and the uniform light reference chart image stored in the storage section, and based on the image of the read object and the peripheral light standard color chart image read by the reading section, wherein

the standard color chart is used to compute a peripheral light intensity ratio of the peripheral light with respect to the uniform light.

2. The image correction device of claim 1, wherein

in (b), the peripheral light intensity ratio of the peripheral light with respect to the uniform light is computed based on the uniform light standard color chart image and the peripheral light standard color chart image, pixel values of each pixel of the uniform light reference chart image are multiplied by the peripheral light intensity ratio, and respective correction coefficients are computed for each pixel by adding the pixel values of corresponding pixels of the self-illuminated reference chart image to the respective pixel values of each of the pixels that have been multiplied by the peripheral light intensity ratio, and an image of the read object in a state not illuminated by the combined light is generated by dividing the pixel values of the corresponding pixels of the image of the read object by the respective correction coefficients.

3. The image correction device of claim 2, wherein

in (b) an image of the read object in a state illuminated by only the self-illumination light is generated by multiplying pixel values of corresponding pixels of the self-illuminated reference chart image by respective pixel values of each of the pixels of the image of the read object in a state not illuminated by the combined light.

4. The image correction device of claim 1, wherein:

the reading section is a line shaped read sensor that has a length direction along a first direction and that reads an image of the read object while scanning in a second direction orthogonal to the first direction; and

in (a) the illumination section and the reading section are controlled such that in a single scan an image of the read object is read in a state illuminated by the peripheral light and the self-illumination light and a peripheral light standard color chart image of the standard color chart is read in a state illuminated by only the peripheral light.

5. The image correction device of claim 4, wherein

in (a) the illumination section and the reading section are controlled such that in a single scan the peripheral light standard color chart image of the standard color chart is read in a state illuminated by only the peripheral light after the image of the read object has been read in a state illuminated by the peripheral light and the self-illumination light.

6. The image correction device of claim 2, wherein:

the storage section stores a self-illuminated standard color chart image of the standard color chart read in advance by the reading section in a state illuminated by only the self-illumination light;

in (a) the illumination section and the reading section are controlled such that a combined light standard color chart image of the standard color chart is read in a state illuminated by the combined light; and

in (b) a self-illumination light intensity ratio is further computed of the self-illumination light when the combined light standard color chart image is read with respect to the self-illumination light when the self-illuminated standard color chart image was read in advance, based on the combined light standard color chart image, the peripheral light standard color chart image and the self-illuminated standard color chart image, and

respective correction coefficients are computed for each of the pixels by adding pixel values of corresponding pixels of the self-illuminated reference chart image that have been multiplied by the self-illumination light intensity ratio to respective pixel values of each of the pixels of the uniform light reference chart image that have been multiplied by the peripheral light intensity ratio.

9. An image reading apparatus comprising:

an illumination section that illuminates self-illumination light from a first light source onto a read object in a state in which peripheral light from a second light source different than the first light source is being illuminated from a periphery of the read object onto the read object;

a standard color chart that is provided in an illuminated region illuminated by the self-illumination light and outside of a mounting region where the read object is mounted;

a reading section that reads an image of the read object and reads an image of the standard color chart;

a storage section that stores a self-illuminated reference chart image of a predetermined reference chart that has been read in advance by the reading section in a state illuminated by the self-illumination light, that stores a uniform light standard color chart image of the standard color chart that has been read in advance by the reading section in a state illuminated by only uniform light from a predetermined uniform light source that illuminates light uniformly on a whole region of the standard color chart and the reference chart, and that stores a uniform light reference chart image of the reference chart that has been read in advance by the reading section in a state illuminated by the uniform light; and

the image correction device of claim 1.

7. An image correction method comprising:

(a) controlling, by a processor, an image reading apparatus including an illumination section that illuminates self-illumination light from a first light source onto a read object in a state in which peripheral light from a second light source different than the first light source is being illuminated from a periphery of the read object onto the read object, a standard color chart that is provided in an illuminated region illuminated by the self-illumination light and outside of a mounting region where the read object is mounted, a reading section that reads an image of the read object and reads an image of the standard color chart, and a storage section that stores a self-illuminated reference chart image of a reference chart of size corresponding to the mounting region that has been read in advance by the reading section in a state illuminated by only the self-illumination light, that stores a uniform light standard color chart image of the standard color chart that has been read in advance by the reading section in a state illuminated by only uniform light from a predetermined uniform light source that illuminates light uniformly on a whole region of the standard color chart and the reference chart, and that stores a uniform light reference chart image of the reference chart that has been read in advance by the reading section in a state illuminated by only the uniform light, by controlling the illumination section of the image reading apparatus and the reading section such that an image of the read object is read in a state illuminated by the peripheral light and by the self-illumination light, and such that a peripheral light standard color chart image of the standard color chart is read in a state illuminated by only the peripheral light when the illumination section is off and peripheral light is illuminated; and

(b) correcting, by the processor, the image of the read object based on the self-illuminated reference chart image, the uniform light standard color chart image and the uniform light reference chart image stored in the storage section, and based on the image of the read object and the peripheral light standard color chart image read by the reading section, wherein

the standard color chart is used to compute a peripheral light intensity ratio of the peripheral light with respect to the uniform light.

8. A non-transitory computer-readable recording medium having stored therein a program for causing a computer to execute an image correction process comprising:

(a) controlling an image reading apparatus including an illumination section that illuminates self-illumination light from a first light source onto a read object in a state in which peripheral light from a second light source different than the first light source is being illuminated from a periphery of the read object onto the read object, a standard color chart that is provided in an illuminated region illuminated by the self-illumination light and outside of a mounting region where the read object is mounted, a reading section that reads an image of the read object and reads an image of the standard color chart, and a storage section that stores a self-illuminated reference chart image of a reference chart of size corresponding to the mounting region that has been read in advance by the reading section in a state illuminated by only the self-illumination light, that stores a uniform light standard color chart image of the standard color chart that has been read in advance by the reading section in a state illuminated by only uniform light from a predetermined uniform light source that illuminates light uniformly on a whole region of the standard color chart and the reference chart, and that stores a uniform light reference chart image of the reference chart that has been read in advance by the reading section in a state illuminated by only the uniform light, by controlling the illumination section of the image reading apparatus and the reading section such that an image of the read object is read in a state illuminated by the peripheral light and the self-illumination light, and such that a peripheral light standard color chart image of the standard color chart is read in a state illuminated by only the peripheral light when the illumination section is off and peripheral light is illuminated; and

(b) correcting the image of the read object based on the self-illuminated reference chart image, the uniform light standard color chart image and the uniform light reference chart image stored in the storage section, and based on the image of the read object and the peripheral light standard color chart image read by the reading section, wherein

the standard color chart is used to compute a peripheral light intensity ratio of the peripheral light with respect to the uniform light.