Image processing apparatus, image processing method, and computer-readable medium

• US 8,842,914 B2
• Filed: 04/23/2013
• Issued: 09/23/2014
• Est. Priority Date: 07/16/2010
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Umeda, Kiyoshi, Sakai, Hiroyuki, Nakagawa, Junichi
• Primary Examiner(s): COUSO, JOSE L
• Application Number:
  US13/869,019
• Publication Number:
  US 20130251258A1
• Time in Patent Office: 518 Days
• Field of Search: 382162-168, 382/190, 382/254, 382/274, 382/275, 358/1.9, 358/3.27, 358/516, 358518-520, 358/523, 348/221.1, 348/223.1
• US Class Current: 382/167
• CPC Class Codes: G06K 15/1878 Adjusting colours image colour correction or control for documents in general H04N1/60
• CPC Class Codes: G06T 5/40 using histogram techniques
• CPC Class Codes: H04N 9/643 Hue control means, e.g. flesh tone control
• CPC Class Codes: H04N 9/73 Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88

Abstract

An image processing apparatus for applying a color balance correction to input image data, comprises a first highlight color calculation unit which estimates a light source at the time of shooting from pixel values of the image data, converts color values of the image data based on a condition of the estimated light source at the time of shooting, and calculates a first highlight color; a second highlight color calculation unit which calculates a second highlight color from the image data; a third highlight color calculation unit which calculates a third highlight color based on a positional relationship between the first highlight color and the second highlight color on a color space; and a correction unit which attains the color balance correction by converting the pixel values of the image data using the third highlight color.

Claims

1. An image processing apparatus comprising:

one or more processors;

an estimation unit configured to estimate a capturing light environment of an image;

a calculation unit configured to calculate a highlight color using the estimated capturing light environment and a histogram calculated from a luminance component of the image; and

a correction unit configured to correct a color balance of the image using the highlight color calculated by the calculation unit.

4. The image processing apparatus according to claim 1,

wherein the calculation unit calculates the highlight color based on a color corresponding to a color temperature of the capturing light environment and luminance obtained from the histogram.

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

a detection unit configured to detect an object included in the image,

wherein the highlight color is calculated further using a color of the object detected by the detection unit.

2. An image processing method comprising:

using one or more processors to perform the steps of;

estimating a capturing light environment of an image;

calculating a highlight color using the estimated capturing light environment and a histogram calculated from a luminance component of the image; and

correcting a color balance of the image using the highlight color calculated in the calculation step.

3. A non-transitory computer-readable storage medium storing a program for controlling a computer to function as:

an estimation unit configured to estimate a capturing light environment of an image;

a calculation unit configured to calculate a highlight color using the estimated capturing light environment and a histogram calculated from a luminance component of the image; and

a correction unit configured to correct a color balance of the image using the highlight color calculated by the calculation unit.