Producing an optimized color image from a negative image and its developed print image

• US 6,295,115 B1
• Filed: 03/01/1999
• Issued: 09/25/2001
• Est. Priority Date: 03/01/1999
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Ahmad, Subutai, Zhang, HongJiang
• Primary Examiner(s): Adams, Russell
• Assistant Examiner(s): NGUYEN, HUNG
• Application Number:
  US09/260,712
• Time in Patent Office: 939 Days
• Field of Search: 355/32, 355/18, 355/22, 355/88.77, 355/40, 355/41, 355/35, 358/518-521, 358/448
• US Class Current: 355/32
• CPC Class Codes: G03B 27/32 Projection printing apparatus, e.g. enlarger, copying camera
• CPC Class Codes: H04N 1/60 Colour correction or control H04N1/54 takes precedence

Abstract

An image processing system for processing digitized color images is described. The image processing system includes a color matching processor that automatically produces an optimized color image from a negative image and its developed print image. The optimized color image processed by the color matching processor has the image resolution and the color appearance of the better one of the negative and the developed print. A method of automatically producing an optimized color image from a negative image and its corresponding print image is also described.

Claims

1. An image processing system for processing digitized color images, comprising:

a color matching processor that produces an optimized color image from a negative image and its developed print image, further comprising

a pixel registration module that builds pixel color correspondences between the negative image and the developed print image such that color shift between the negative image and the developed print is determined at each pixel;

a color mapping module coupled to the pixel registration module to generate a color map that can transform the colors between the negative image and the developed print image;

a color correction module coupled to the color mapping module to transform and correct colors of one of the negative image and the developed print image using the color map generated by the color mapping module.

2. The image processing system of claim 1, wherein the color map is represented as a three dimensional color histogram having a plurality of bins, each containing an update vector.

3. The image processing system of claim 1, wherein the color correction module transforms and corrects colors of the negative image globally by

computing an average update vector for each bin of the color histogram;

applying the color components of the update vector of a bin to the corresponding pixel in the negative image such that details in the negative image are preserved.

4. The image processing system of claim 1, wherein the color correction module transforms and corrects colors of the negative image locally by

updating the color values of each pixel of the negative image to match with that of the corresponding pixel of the print image;

applying a global scale factor to the intensity value of the negative image.

5. The image processing system of claim 1, wherein the pixel registration module builds pixel color correspondences between the negative image and the developed print image by

computing a grey scale, histogram equalized version of each of the negative image and the developed print image;

and

determining a set of affine parameters that best transform one of the negative image and the print image into the other one of the negative image and the print image.

6. A method of producing an optimized color image from a negative image and its corresponding print image, comprising the steps of:

(A) building pixel color correspondences between the negative image and the corresponding print image such that color shift of the negative image from the corresponding print image is determined at each pixel; and

(B) producing the optimized color image using the color map by transforming the color distribution of the print image to the negative image at each pixel, wherein the color map is represented as a three dimensional color histogram having a plurality of bins, each containing an update vector.

7. The method of claim 6, wherein the step (B) is performed globally by

computing an average update vector for each bin of the color histogram;

applying the color components of the update vector of a bin to the corresponding pixel in the negative image such that details in the negative image are preserved.

8. The method of claim 6, wherein the step (B) is performed locally by

updating the color values of each pixel of the negative image to match with that of the corresponding pixel of the corresponding print image;

applying a global scale factor to the intensity value of the negative image.

9. The method of claim 6, wherein the step (A) further comprises the steps of

computing a grey scale, histogram equalized version of each of the negative image and the corresponding print image;

and

determining a set of affine parameters that best transform the corresponding print image into the negative image.

10. The method of claim 9, wherein the step (A) further comprises the step of generating a color map that can transform the colors of the negative image to look like the corresponding print image.