Image processing apparatus and method

• US 6,449,060 B1
• Filed: 07/22/1997
• Issued: 09/10/2002
• Est. Priority Date: 07/22/1996
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Aoyagi, Takeshi, Kawai, Takashi, Matsuya, Akihiro
• Primary Examiner(s): ROGERS, SCOTT A
• Application Number:
  US08/898,255
• Time in Patent Office: 1,876 Days
• Field of Search: 358/1.9, 358/504, 358/500, 358/515, 358/530, 382/162
• US Class Current: 358/1.9
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/20192 Edge enhancement; Edge preservation
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 5/73 Deblurring; Sharpening
• CPC Class Codes: H04N 1/40012 Conversion of colour to monochrome
• CPC Class Codes: H04N 1/4092 Edge or detail enhancement
• CPC Class Codes: H04N 1/46 Colour picture communication systems
• CPC Class Codes: H04N 1/6072 adapting to different types of images, e.g. characters, graphs, black and white image portions

Abstract

This invention provides an image processing apparatus which simplifies the circuit arrangement required for edge emphasis correction. For this purpose, the apparatus has a first color conversion unit (102) for color-separating input image data into lightness data and chromaticity data, a delay unit (103) for delaying the separated lightness data by N lines, and delaying the chromaticity data by N/2 lines, an image edge amount extraction unit (113) for extracting an image edge portion from the lightness data, a saturation amount extraction unit (114) for extracting the saturation component from the chromaticity data, and an image edge emphasis amount distribution unit (116) for distributing the emphasis amount of the edge portion to an edge emphasis unit (104) so that the distribution ratio for chromaticity correction is higher than that for lightness correction when the saturation component extracted by the saturation extraction unit (114) is large, and the distribution ratio for lightness correction is higher than that for chromaticity correction when the saturation component extracted by the saturation extraction unit (114) is small.

Claims

1. An image processing apparatus having a function of discriminating whether an input image is a color image or not, comprising:

determination means for determining whether a pixel of interest is a chromatic color pixel; and

discrimination means for discriminating in accordance with continuity of determination results of said determination means in two-dimensional directions whether the input image is a color image,

wherein said discrimination means includes first decision means for deciding if chromatic color pixels continue in a main scanning direction,

wherein said discrimination means further includes second decision means for deciding if the number of portions including continuous chromatic color pixels in the main scanning direction is not less than a predetermined value, and

wherein said discrimination means further includes third decision means for deciding if not less than a predetermined number of chromatic color lines continue in a sub-scanning direction.

2. An image processing method having a function of discriminating whether an input image is a color image or not, comprising:

a determination step of determining whether a pixel of interest is a chromatic color pixel; and

a discrimination step of discriminating in accordance with continuity of determination results in the determination step in two-dimensional directions if the input image is a color image,

wherein the discrimination step includes the first decision step of deciding if chromatic color pixels continue in a main scanning direction,

wherein the discrimination step further includes a second decision step of deciding if the number of portions including continuous chromatic color pixels in the main scanning direction is not less than a predetermined value, and

wherein the discrimination step further includes a third decision step of deciding if not less than a predetermined number of chromatic color lines continue in a sub-scanning direction.