Method for including traditional photographic calibration into digital color management

• US 6,501,850 B2
• Filed: 06/19/1998
• Issued: 12/31/2002
• Est. Priority Date: 02/04/1998
• Status: Expired due to Fees

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Setchell, John S. Jr.
• Primary Examiner(s): Wu, Jingge
• Application Number:
  US09/100,217
• Publication Number:
  US 20020085749A1
• Time in Patent Office: 1,656 Days
• Field of Search: 382/162, 382/167, 358/516, 358/515, 358/524, 358/525, 358/500, 358/504, 358/527, 358/518, 358/521, 358/506, 358/523, 358/406, 358/1.9, 358/1.6, 358/520, 356/243, 345/431, 345/150, 345/154, 345/432, 345/589, 345/605, 708/290, 708/847, 347/19, 347/115, 347/172, 348/223, 348/254
• US Class Current: 382/162
• CPC Class Codes: G06K 15/02 using printers
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

A method for including photographic calibration into digital color management having an abstract color transformation profile, the method comprises the steps of measuring a density from a patch of an optically created image; inputting the measured densities to a computer workstation; computing a density to colorimetry matrix that is received by the computer workstation; and interpolating the matrix based on the inputted density for creating the abstract profile for ultimately permitting modification of an image manipulated by the abstract profile.

Claims

1. A method for including photographic calibration from a photographic process into digital color management having an abstract color transformation profile operative in a profile connection space, the method comprising the steps of:

(a) measuring density values from one or more density patches on a test image produced by the photographic process and which represents an optical process aim, thereby providing measured density data;

(b) providing a transform for transforming between density data and colorimetry data based on spectrophotometric data of a particular paper representative of typical dye sets used in the photographic process, wherein the transform is operative in a CIE psychometric lightness space;

(c) providing a 3-dimensional table having table values for uniformly sampling the profile connection space;

(d) converting the table values into a lightness function;

(e) transforming the table values into a density function using said transform provided in step (b);

(f) finding table values corresponding to physically realizable colors;

(g) adjusting the table values corresponding to physically realizable colors to the optical process aim by 1-D interpolation from a digital process aim using the measured density values from step (a);

(h) transforming the adjusted table values back to colorimetric values by using an inverse of said transform provided in step (b);

(i) transforming the colorimetric values to the profile connection space by using a relationship inverse to that used in step (d); and

(j) saving the transformed colorimetric values as an abstract color transformation profile.

2. The method as claimed in claim 1 wherein the particular density function in step (e) is a psychometric lightness function of the antilogarithm of a negative density.

3. The method as claimed in claim 1 wherein the transform in step (b) is a 3×

3 matrix transformation translating between density data and colorimetry data that is computed using a least squares regression technique.

4. A computer program product for including photographic calibration from a photographic process into digital color management having an abstract color transformation profile operative in a profile connection space, said computer program product comprising:

a computer readable storage medium having a computer program stored thereon for performing the steps of;

(a) measuring density values from one or more density patches on a test image produced by the photographic process and which represents an optical process aim, thereby providing measured density data;

(b) providing a transform for transforming between density data and colorimetry data based on spectrophotometric data of a particular paper representative of typical dye sets used in the photographic process, wherein the transform is operative in a CIE psychometric lightness space;

(c) providing a 3-dimensional table having table values for uniformly sampling the profile connection space;

(d) converting the table values into a lightness function;

(e) transforming the table values into a density function using said transform provided in step (b);

(f) finding table values corresponding to physically realizable colors;

(g) adjusting the table values corresponding to physically realizable colors to the optical process aim by 1-D interpolation from a digital process aim using the measured density values from step (a);

(h) transforming the adjusted table values back to colorimetric values by using an inverse of said transform provided in step (b);

(i) transforming the colorimetric values to the profile connection space by using a relationship inverse to that used in step (d); and

(j) saving the transformed colorimetric values as an abstract color transformation profile.

5. The computer program product as claimed in claim 4 wherein the particular density function in step (e) is a psychometric lightness function of the antilogarithm of a negative density.

6. The computer program product as claimed in claim 4 wherein the transform in step (b) is a 3×

3 matrix transformation translating between density data and colorimetry data that is computed using a least squares regression technique.