Colorant-amount transforming method

• US 5,687,000 A
• Filed: 08/29/1995
• Issued: 11/11/1997
• Est. Priority Date: 03/24/1995
• Status: Expired due to Term

• Current Assignee: TOYO Ink Manufacturing Company Limited (artience Co. Ltd.)
• Original Assignee: TOYO Ink Manufacturing Company Limited (artience Co. Ltd.)
• Inventors: Nakaoka, Ikuo
• Primary Examiner(s): FRAHM, ERIC S
• Application Number:
  US08/520,760
• Time in Patent Office: 805 Days
• Field of Search: 358/296, 358/298, 358/500, 358/501, 358/503, 358/504, 358/515, 358/518-521, 358/523-525, 358/530, 358/534, 382/162, 382/167, 347/106, 347/172, 347/183, 347/184
• US Class Current: 358/296
• CPC Class Codes: H04N 1/6011 with simulation on a subsidiary picture reproducer H04N1/622 takes precedence; matching two or more picture reproducers H04N1/6052
• CPC Class Codes: H04N 1/6019 using look-up tables H04N1/6025 takes precedence

Abstract

A colorant-amount transforming method for transforming a first colorant amount for forming an image on a first medium into a second colorant amount for forming the image on a second medium whose colorimetric value differs from that of the first medium. The first colorant amount is transformed into a colorimetric value by a first transformation for transforming the first colorant amount into a colorimetric value corresponding to a tristimulus value (or a spectral reflectance) in which a portion of contribution of the tristimulus value (spectral reflectance) of the first medium itself to the tristimulus value (spectral reflectance) of the image formed on the first medium with the first colorant amount is replaced by the tristimulus value (spectral reflectance) of the second medium itself in accordance with a contribution rate. The colorimetric value obtained in the first transformation is transformed into the second colorant amount by a second transformation for transforming the colorimetric value of the image formed on the second medium into the second colorant amount.

Claims

1. A colorant-amount transforming method for transforming a first colorant amount for forming an image on a first medium into a second colorant amount for forming the image on a second medium whose colorimetric value differs from that of the first medium, comprising the steps of:

(a) transforming the colorant amount subject to transformation into a colorimetric value by a first transformation for transforming the first colorant amount into a colorimetric value corresponding to one of a tristimulus value and a spectral reflectance in which a portion of contribution of one of the tristimulus value and the spectral reflectance of the first medium itself to one of the tristimulus value and the spectral reflectance of the image formed on the first medium with the first colorant amount is replaced by one of the tristimulus value and the spectral reflectance of the second medium itself in accordance with a contribution rate; and

(b) transforming the colorimetric value obtained by the transformation in step (a) into a colorant amount targeted in the transformation by a second transformation in which the colorimetric value of the image formed on the second medium with the second colorant amount is transformed into the second colorant amount.

2. A colorant-amount transforming method according to claim 1, wherein the colorimetric value in the first transformation in step (a) is a colorimetric value corresponding to one R'"'"'a of the tristimulus value and the spectral reflectance which is given by the following formula:

space="preserve" listing-type="equation">R'"'"'a=RA+Ka(Wb-Wa)

where,

RA is one of the tristimulus value and the spectral reflectance of the image formed on the first medium with the first colorant amount,

Ka is the contribution rate,

Wa is one of the tristimulus value and the spectral reflectance of the first medium itself, and

Wb is one of the tristimulus value and the spectral reflectance of the second medium itself.

3. A colorant-amount transforming method according to claim 1, wherein when a first colorant for forming the image on the first medium is of n kinds, and each of colorant amounts thereof ranges in steps of from a1 to an %, the contribution rate Ka is given by the following formula:

space="preserve" listing-type="equation">Ka=(1-a.sub.1 /100)×

(1-a.sub.2 /100) x . . . x (1-a.sub.n /100).

4.

4. A colorant-amount transforming method according to claim 1, wherein the contribution rate Ka is given by the following formula:

space="preserve" listing-type="equation">Ka=(Ra-Rb)/(Wa-Wb)

where,

Ra is one of the tristimulus value and the spectral reflectance of the image formed on the first medium with a predetermined colorant amount,

Rb is one of the tristimulus value and the spectral reflectance of the image formed on the second medium with a predetermined colorant amount,

Wa is one of the tristimulus value and the spectral reflectance of the first medium itself, and

Wb is one of the tristimulus value and the spectral reflectance of the second medium itself.

5. A colorant-amount transforming method according to claim 1, wherein in a case where the image is formed by an area gradation method, the contribution rate is given by a ratio of an area of a portion of the first medium not covered with the colorant to an overall area of the first medium.

6. A colorant-amount transforming method according to claim 1, wherein, in step (a), the colorant amount subject to transformation is transformed into a colorimetric value corresponding to one of the tristimulus value and the spectral reflectance in which the portion of contribution of one of the tristimulus value and the spectral reflectance of the first medium itself to one of the tristimulus value and the spectral reflectance of the image formed on the first medium with the first colorant amount is replaced by one of the tristimulus value and the spectral reflectance of a third medium itself in accordance with the contribution rate.

7. A colorant-amount transforming method according to claim 6, wherein, in step (b), the colorimetric value obtained by the transformation in step (a) is transformed into a colorant amount for displaying on an image displaying device, by the second transformation for transforming into the second colorant amount the colorimetric value of the image formed on the second medium with the second colorant amount.

8. A colorant-amount transforming method according to claim 6, wherein the first colorant amount in step (a) is made correctable.

9. A colorant-amount transforming method for transforming a first colorant amount for forming an image on a first medium into a second colorant amount for forming the image on a second medium whose colorimetric value differs from that of the first medium, comprising the steps of:

(a) transforming the colorant amount subject to transformation into a colorimetric value by a first transformation for transforming the first colorant amount into a colorimetric value of the image formed on the first medium with the first colorant amount; and

(b) transforming the colorimetric value obtained by the transformation in step (a) into a colorant amount targeted in the transformation by a second transformation for transforming into the second colorant amount a colorimetric value corresponding to one of a tristimulus value and a spectral reflectance in which a portion of contribution of one of the tristimulus value and the spectral reflectance of the second medium itself to one of the tristimulus value and the spectral reflectance of the image formed on the second medium with the second colorant amount is replaced by one of the tristimulus value and the spectral reflectance of the first medium itself in accordance with a contribution rate.

10. A colorant-amount transforming method according to claim 9, wherein the colorimetric value in the second transformation in step (b) is a colorimetric value corresponding to one R'"'"'b of the tristimulus value and the spectral reflectance which is given by the following formula:

space="preserve" listing-type="equation">R'"'"'b=RB+Kb(Wa-Wb)

where,

RB is one of the tristimulus value and the spectral reflectance of the image formed on the second medium with the second colorant amount,

Kb is the contribution rate,

Wa is one of the tristimulus value and the spectral reflectance of the first medium itself, and

Wb is one of the tristimulus value and the spectral reflectance of the second medium itself.

11. A colorant-amount transforming method according to claim 9, wherein when a second colorant for forming the image on the second medium is of m kinds, and each of colorant amounts thereof ranges in steps of from b₁ to b_m %, the contribution rate Kb is given by the following formula:

space="preserve" listing-type="equation">Kb=(1-b.sub.1 /100)×

(1-b.sub.2 /100) . . . x (1-b.sub.m /100).

12.

12. A colorant-amount transforming method according to claim 9, wherein the contribution rate Kb is given by the following formula:

space="preserve" listing-type="equation">Kb=(Ra-Rb)/(Wa-Wb)

where,

Ra is one of the tristimulus value and the spectral reflectance of the image formed on the first medium with a predetermined colorant amount,

Rb is one of the tristimulus value and the spectral reflectance of the image formed on the second medium with a predetermined colorant amount,

Wa is one of the tristimulus value and the spectral reflectance of the first medium itself, and

Wb is one of the tristimulus value and the spectral reflectance of the second medium itself.

13. A colorant-amount transforming method according to claim 9, wherein in a case where the image is formed by an area gradation method, the contribution rate is given by a ratio of an area of a portion of the second medium not covered with the colorant to an overall area of the second medium.

14. A colorant-amount transforming method according to claim 9, wherein, in step (b), a colorimetric value, corresponding to one of the tristimulus value and the spectral reflectance in which the portion of contribution of one of the tristimulus value and the spectral reflectance of the second medium itself to one Of the tristimulus value and the spectral reflectance of the image formed on the second medium with the second colorant amount is replaced by one of the tristimulus value and the spectral reflectance of a third medium itself in accordance with the contribution rate, is transformed into a colorant amount targeted in the transformation.

15. A colorant-amount transforming method for transforming a first colorant amount for forming an image on a first medium into a second colorant amount for forming the image on a second medium whose colorimetric value differs from that of the first medium, comprising the steps of:

(a) transforming the colorant amount subject to transformation into a colorimetric value by a first transformation for transforming the first colorant amount into a colorimetric value corresponding to one of a tristimulus value and a spectral reflectance in which a portion of contribution of one of the tristimulus value and the spectral reflectance of the first medium itself to one of the tristimulus value and the spectral reflectance of the image formed on the first medium with the first colorant amount is replaced by one of the tristimulus value and the spectral reflectance of some standard white in accordance with a contribution rate; and

(b) transforming the colorimetric value obtained by the transformation in step (a) into a colorant amount targeted in the transformation by a second transformation for transforming into the second colorant amount a colorimetric value corresponding to one of a tristimulus value and a spectral reflectance in which a portion of contribution of one of the tristimulus value and the spectral reflectance of the second medium itself to one of the tristimulus value and the spectral reflectance of the image formed on the second medium with the second colorant amount is replaced by one of the tristimulus value and the spectral reflectance of the white used in step (a) in accordance with a contribution rate.