Color image conversion method and system for reducing color image data size

• US 7,298,894 B2
• Filed: 06/18/2003
• Issued: 11/20/2007
• Est. Priority Date: 06/18/2003
• Status: Expired due to Fees

• Current Assignee: Pirmax Electronics, Ltd.
• Original Assignee: Primax Electronics Limited
• Inventors: Chen, Guo-Tai
• Primary Examiner(s): Alavi, Amir
• Application Number:
  US10/463,334
• Publication Number:
  US 20040258298A1
• Time in Patent Office: 1,616 Days
• Field of Search: 382/162, 382/166, 382/167, 382/172, 382/218, 382/219, 382/305, 345/589, 345/592, 345600-604, 358/515, 358/518, 375/240.25, 348/143
• US Class Current: 382/167
• CPC Class Codes: H04N 1/40012 Conversion of colour to monochrome
• CPC Class Codes: H04N 1/40062 Discrimination between different image types, e.g. two-tone, continuous tone
• CPC Class Codes: H04N 1/56 Processing of colour picture signals H04N1/52 takes precedence

Abstract

A color image conversion method and the associated system are disclosed. An allowed error range of pixels is determined. After an image input device reads a document, the pixel information and the pixel allowed error range are compared to determine whether the document is a color or black-and-white (BW) one. If it is a BW document, the image file is directly converted into a monochromic and grey-level one and stored in 8-bit or even 1-bit format, thereby reducing the storage space occupied by the image file.

Claims

1. A color image conversion method for reducing the image data size of a monochrome document scanned by a image input device, comprising the steps of:

setting a tolerable error range for pixels;

reading a source document to generate an original color image file;

checking whether the pixel values derived from the original color image file fall within the tolerable error range;

converting the original color image file into a monochrome image file to reduce the data, if all of the pixel values derived from the original color image file fall within the tolerable error range; and

storing the converted file.

2. The method of claim 1, wherein the original color image file is a 24-bit image file.

3. The method of claim 1, wherein the monochrome image file is a 1-bit monochromatic image file.

4. The method of claim 1, wherein the monochrome image file is an 8-bit grey-level image file.

5. The method of claim 1, wherein the original color image file is stored when its pixel values are determined to fall outside the tolerable error range.

6. The method of claim 1, wherein the step of converting the original color image file into a monochrome image file to reduce the data is followed by the step of checking whether the monochrome image file is a grey-level image file.

7. The method of claim 6, wherein the image file is stored as a black-and-white image file when it is determined not to be a grey-level image file.

8. The method of claim 1, wherein the image, input device detects red, green, and blue values for each pixel, and further comprising the step of combining color values for each pixel before conducting the checking step.

9. A color image conversion system for reducing the image data size of a monochrome scanned document, comprising:

a reading module, which scans the document to generate an original color image file;

a central processing module, which analyzes the pixel information in the original color image file and converts the original color image file into a monochrome image file, the analysis including determining whether pixel values derived from the original image file fall within a predetermined error range; and

a storage module, which stores the monochrome image file converted by the central processing module.

10. The system of claim 9, wherein the original color image file is a 24-bit image file.

11. The system of claim 9, wherein the monochrome image file is a 1-bit monochromatic image file.

12. The system of claim 9, wherein the monochrome image file is an 8-bit grey-level image file.