Image capture apparatus which synthesizes a plurality of images obtained by shooting a subject from different directions, to produce an image in which the influence of glare from a light is reduced

• US 7,760,962 B2
• Filed: 03/28/2006
• Issued: 07/20/2010
• Est. Priority Date: 03/30/2005
• Status: Expired due to Fees

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Sakurai, Keiichi, Sambongi, Masao
• Primary Examiner(s): Mehta; Bhavesh M
• Assistant Examiner(s): Thirugnanam; Gandhi
• Application Number:
  US11/390,808
• Publication Number:
  US 20060222260A1
• Time in Patent Office: 1,575 Days
• Field of Search: 382/115, 382153-154, 382/274
• 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 shoots a document plural times from different directions to obtain a plurality of images. An image processing device included in the digital camera 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 which corrects distortion of a shape of a subject in a plurality of captured images obtained by shooting the subject from different directions, to obtain distortion-corrected images;

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

wherein the image synthesis unit;

obtains a parameter indicating an intensity of a light when the subject is shot 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 first case in which 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 second case in which 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 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 cases other than the first and second cases,

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

2. The image capture apparatus according to claim 1, wherein the parameter indicating the intensity of the light when the subject is shot is obtained for each pixel based on a luminance value for the pixel.

3. The image capture apparatus according to claim 1, wherein the parameter indicating the intensity of the light when the subject is shot is obtained for each pixel based on a hue value for the pixel.

4. The image capture apparatus according to claim 1, wherein the parameter indicating the intensity of the light when the subject is shot is obtained for each pixel based on the pixel value of the pixel and pixel values of pixels in an area surrounding the pixel.

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

a base unit;

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

an imaging unit and an illuminator which are set on an upper portion of the arm.

6. An image processing method, performed by an image capture apparatus for capturing an image of a subject, the method comprising:

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

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

wherein performing the predetermined calculation and synthesizing the corrected image comprises;

obtaining a parameter indicating an intensity of a light when the subject is shot for each pixel from a first image and a second image which are to be synthesized, and obtaining 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;

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

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

selecting a value obtained by 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 cases other than the first and second cases,

thereby synthesizing the corrected image from the plurality of distortion-corrected images.

7. A tangible computer-readable recording medium storing a program that is executable by a computer to cause the computer to function as:

a correction unit which corrects distortion of a shape of a subject in a plurality of captured images obtained by shooting the subject from different directions, 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 a corrected image from the plurality of distortion-corrected images;

wherein the image synthesis unit;

obtains a parameter indicating an intensity of a light when the subject is shot 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 first case in which 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 second case in which 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 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 cases other than the first and second cases,

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