Image capture apparatus, image processing method for captured image, and recording medium

• US 20060222260A1
• Filed: 03/28/2006
• Published: 10/05/2006
• Est. Priority Date: 03/30/2005
• Status: Active Grant

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Sakurai, Keiichi, Sambongi, Masao
• Granted Patent: US 7,760,962 B2
• Time in Patent Office: Days
• US Class Current: 382/274
• CPC Class Codes: G06T 5/50 using two or more images, e.g. averaging or subtraction
• CPC Class Codes: G06T 5/80 Geometric correction

Abstract

A digital camera (1) shoots a document plural times from different directions to obtain a plurality of images. An image processing device included in the digital camera (1) corrects the keystone distortion of each image to generate an image which seems as if the document were shot from in front of it. The image processing device synthesizes the images by addition-averaging the pixel values of each pixel in the plurality of corrected images. Even if captured images are illuminated by glare from a light because a document made of glossy paper is shot, the influence of the glare is reduced by addition-averaging the pixel values of each pixel in the plurality of images.

Claims

1. An image capture apparatus for capturing an image of a subject, comprising:

a correction unit (25) which corrects distortions of a plurality of captured images obtained by shooting the subject from different directions, to obtain distortion-corrected images; and

an image synthesis unit (25) which performs a predetermined calculation for each pixel in the plurality of distortion-corrected images obtained by the correction unit (25) in order to reduce a change in a pixel value which is caused by glare from a light, and synthesizes an corrected image from the plurality of distortion-corrected images.

2. The image capture apparatus according to claim 1,

wherein the image synthesis unit (25) synthesizes an corrected image from the plurality of distortion-corrected images by obtaining an addition average of pixel values in the plurality of distortion-corrected images for each pixel.

3. The image capture apparatus according to claim 1,

wherein the image synthesis unit (25) synthesizes an corrected image from the plurality of distortion-corrected images by obtaining a smallest value among pixel values in the plurality of distortion-corrected images for each pixel.

4. The image capture apparatus according to claim 1,

wherein the image synthesis unit (25) synthesizes an corrected image from the plurality of distortion-corrected images by obtaining a parameter indicating an intensity of a light when the subject is shot for each pixel in the plurality of distortion-corrected images, comparing values of the obtained parameters for each pixel at a corresponding position in the plurality of distortion-corrected images, and selecting a pixel value of a distortion-corrected image in which the value of the parameter is smaller.

5. The image capture apparatus according to claim 4,

wherein the image synthesis unit (25):

obtains the parameter for each pixel from a first image and a second image which are to be synthesized, and obtains a difference obtained by subtracting a value of the parameter of the first image from a value of the parameter of the second image for each pixel;

selects a pixel value of the second image to be a pixel value of a synthesized image, in a case where the obtained difference is smaller than a preset first threshold;

selects a pixel value of the first image to be a pixel value of a synthesized image, in a case where the first image is already a synthesized image having been synthesized before, and the obtained difference is larger than a preset second threshold; and

selects a value obtained by addition-averaging the pixel value of the first image and the pixel value of the second image based on a number of times image synthesis has been performed, to be a pixel value of a synthesized image, in other cases than above,

thereby to synthesize an corrected image from the plurality of distortion-corrected images.

6. The image capture apparatus according to claim 4,

wherein the image synthesis unit (25) synthesizes an corrected image from the plurality of distortion-corrected images by obtaining a luminance value of the distortion-corrected images, comparing the luminance values for each pixel at a corresponding position in the plurality of distortion-corrected images, and selecting a pixel value of a distortion-corrected image in which the luminance value is smaller.

7. The image capture apparatus according to claim 4,

wherein the image synthesis unit (25) synthesizes an corrected image from the plurality of distortion-corrected images by obtaining a hue value of the distortion-corrected images, comparing the hue values for each pixel at a corresponding position in the plurality of distortion-corrected images, and selecting a pixel value of a distortion-corrected image in which the hue value is smaller.

8. The image capture apparatus according to claim 1,

wherein the image synthesis unit (25) synthesizes an corrected image from the plurality of distortion-corrected images by adding up luminance values of an area surrounding a pixel being focused to obtain a pixel value of the pixel being focused.

9. The image capture apparatus according to claim 1, comprising:

a base unit (115);

an arm (117) axially supported by the base unit (15) in a free-to-swing state; and

an imaging unit (111) and an illuminator (112) which are set on an upper portion of the arm (117).

10. An image processing method for a captured image obtained by shooting a subject, comprising:

a step of shooting the subject from different directions, and correcting distortions of a plurality of images obtained by the shooting to obtain a plurality of distortion-corrected images; and

a step of performing a predetermined calculation for reducing a change in a pixel value caused by glare from a light, and synthesizing an corrected image from the plurality of distortion-corrected images.

11. A recording medium storing a program for controlling a computer to function as:

a correction unit which shoots a subject from different directions, and corrects distortions of a plurality of images obtained by the shooting to obtain a plurality of distortion-corrected images; and

an image synthesis unit which performs a predetermined calculation for reducing a change in a pixel value caused by glare from a light, and synthesizes an corrected image from the plurality of distortion-corrected images.