Color proofing method and apparatus, and recorded medium on which color proofing program is recorded

A color proofing method for improving the color reproducibility of printed matter to be produced by a printing press in proof print produced by a proof press, the color proofing method comprising the steps of:

• creating a look-up table containing converted values of image data over the entire color space with respect to the proof press;
• correcting the look-up table based on the color of printing paper for the printing press and a paper exposed area factor in the proof print;
• making proof print by the use of the corrected look-up table;
• in the case where the proof print is produced based on area gradation and the colors of the printing paper for the printing press and a printing paper for the proof press are approximated to each other to such an extent as not to need to take the ink transmittance into account, the step of correcting the look-up table includes the steps of:
• determining a paper exposed area factor α in accordance with the following equation when arbitrary reference data P in the look-up table has color values (Cp, Mp, Yp, Bkp), each of which is N-bit data:
• α=(1−Cp/(2N−1))×(1−Mp/(2N−1))×(1−Yp/(2N−1))×(1−Bkp/(2N−1)),
• in contrast, determining the paper exposed area factor α in accordance with the following equation when the arbitrary reference data P in the look-up table has the color values (Cp, Mp, Yp, Bkp), each of which is percentage data:
• α=(1−Cp/100)×(1−Mp/100)×(1−Yp/100)×(1−Bkp/100);
• and determining corrected values (Ci′, Mi′, Yi′, Bki′) of color values (Ci, Mi, Yi, Bki) of arbitrary reference data I in the look-up table in accordance with the following equations when color values (Ca, Ma, Ya, Bka) of the printing paper for the printing press are added to a part where a paper exposed area factor is 100%:
• Ci′=Ci+Ca×α, Mi′=Mi+Ma×α, Yi′=Yi+Ya×α and Bki′=Bki+Bka×α,
• to thus replace the color values of the reference data with the corrected values.

A color proofing method for improving the color reproducibility of printed matter to be produced by a printing press in proof print produced by a proof press, the color proofing method comprising the steps of:

• creating a look-up table containing converted values of image data over the entire color space with respect to the proof press;
• correcting the look-up table based on the color of printing paper for the printing press and a paper exposed area factor in the proof print;
• making proof print by the use of the corrected look-up table;
• in the case where the colors of the printing paper for the printing press and a printing paper for the proof press are different from each other to such an extent as to need to take the ink transmittance into account, the step of correcting the look-up table includes the step of:
• determining corrected values (Ci′, Mi′, Yi′, Bki′) of color values (Ci, Mi, Yi, Bki) of arbitrary reference data I in the look-up table in accordance with the following equations when color values (Ca, Ma, Ya, Bka) of the printing paper for the printing press are added to a part where a paper exposed area factor is 100%, wherein address values (Cid, Mid, Yid, Bkid) express the color values (Ci, Mi, Yi, Bki) by N-bit:
• Ci′=Ci+Ca×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• Mi′=Mi+Ma×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• Yi′=Yi+Ya×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• and
• Bki′=Bki+Bka×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• to thus replace the color values of the reference data with the corrected values.

A color proofing method for improving the color reproducibility of printed matter to be produced by a printing press in proof print produced by a proof press, the color proofing method comprising the steps of:

• creating a look-up table containing converted values of image data over the entire color space with respect to the proof press;
• correcting the look-up table based on the color of printing paper for the printing press and a paper exposed area factor in the proof print;
• making proof print by the use of the corrected look-up table;
• in the case where the proof print is produced based on both of density gradation and area gradation and the colors of the printing paper for the printing press and a printing paper for the proof press are approximated to each other to such an extent as not to need to take the ink transmittance into account, the step of correcting the look-up table includes the steps of:
• specifying an influence range defining how far reference data is influenced in the color space when the color values of the printing paper for the printing press are added to the color space;
• and
• determining an influence value for each of the reference data based on the color values of the paper and the value of the influence range, to thus add the influence value to the reference data.

A computer readable medium recording therein a color proofing program for improving the color reproducibility of printed matter to be produced by a printing press in proof print produced by a proof press by the use of a computer, the color proofing program instructing the computer to execute the processes of:

• creating a look-up table containing converted values of image data over the entire color space with respect to the proof press;
• correcting the look-up table based on the color of printing paper for the printing press and a paper exposed area factor in the proof print;
• creating proof print by the use of the corrected look-up table;
• in the case where the proof print is produced based on only area gradation and the colors of the printing paper for the printing press and a printing paper for the proof press are approximated to each other to such an extent as not to need to take the ink transmittance into account, the look-up table correcting process includes the processes of:
• determining a paper exposed area factor α in accordance with the following equation when arbitrary reference data P in the look-tip table has color values (Cp, Np, Yp, Bkp), each of which is N-bit data:
• α=(1−Cp/(2N−1))×(1−Mp/(2N−1))×(1−Yp/(2N−1))×(1−Bkp/(2N−1)),
• in contrast, determining the paper exposed area factor α in accordance with the following equation when the arbitrary reference data P in the look-up table has the color values (Cp, Mp, Yp, Bkp), each of which is percentage data:
• α=(1−Cp/100)×(1−Mp/100)×(1−Yp/100)×(1−Bkp/100);
• and
• determining corrected values (Ci′, Ni′, Yi′, Bki′) of color values (Ci, Ni, Yi, Bki) of arbitrary reference data I in the look-up table in accordance with the following equations when color values (Ca, Ma, Ya, Bka) of the printing paper for the printing press are added to a part where a paper exposed area factor is 100%:
• Ci′=Ci+Ca×α, Mi′=Mi+Ma×α, Yi′=Yi+Ya×α and Bki′=Bki+Bka×α,
• to thus replace the color values of the reference data with the corrected values.

A color proofing apparatus for improving the color reproducibility of printed matter to be produced by a printing press in proof print produced by a proof press by the use of a computer, the color proofing apparatus comprising:

• a look-up table creating section for creating a look-up table including converted values of image data over the entire color space with respect to the proof press;
• a noise strength and distribution amount input section for setting the noise strength and distribution amount indicating the level of a variation of the color of the printing paper for the printing press;
• a paper color input section for specifying the color of the printing paper for the printing press;
• a look-up table correcting section for correcting the look-up table based on the color inputted to the paper color input section and a paper exposed area factor in the proof print and
• an image data converting section for changing the image data converted by the use of the look-up table corrected by the look-up table correcting section based on the noise strength and distribution amount inputted to the noise strength and distribution amount input section, to thus output the changed image data
• in the case where the proof print is produced based on both of density gradation and area gradation and the colors of the printing paper for the printing press and a printing paper for the proof press are approximated to each other to such an extent as not to need to take the ink transmittance into account, the look-up table correcting section includes:
• an influence range input section for specifying an influence range defining how far reference data is influenced in the color space when the color values of the printing paper for the printing press are added to the color space;
• and
• an influence value calculating section for determining an influence value for each of the reference data based on the color values of the paper and the value of the influence range, to thus add the influence value to the reference data.

A color proofing apparatus for improving the color reproducibility of printed matter to be produced by a printing press in proof print produced by a proof press by the use of a computer, the color proofing apparatus comprising:

• a look-up table creating section for creating a look-up table including converted values of image data over the entire color space with respect to the proof press;
• a noise strength and distribution amount input section for setting the noise strength and distribution amount indicating the level of a variation of the color of the printing paper for the printing press;
• a paper color input section for specifying the color of the printing paper for the printing press;
• a look-up table correcting section for correcting the look-up table based on the color inputted to the paper color input section and a paper exposed area factor in the proof print and
• an image data converting section for changing the image data converted by the use of the look-up table corrected by the look-up table correcting section based on the noise strength and distribution amount inputted to the noise strength and distribution amount input section, to thus output the changed image data;
• in the case where the colors of the printing paper for the printing press and a printing paper for the proof press are different from each other to such an extent as to need to take the ink transmittance into account, the look-up table correcting section includes:
• a second color corrected value calculating section for determining corrected values (Ci′, Ni′, Yi′, Bki′) of color values (Ci, Mi, Yi, Bki) of arbitrary reference data I in the look-up table in accordance with the following equations when color values (Ca, Ma, Ya, Bka) of the printing paper for the printing press are added to a part where a paper exposed area factor is 100%, wherein address values (Cid, Mid, Yid, Bkid) express the color values (Ci, Mi, Yi, Bki) by N-bit:
• Ci′=Ci+Ca×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• Mi′=Mi+Ma×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• Yi′=Yi+Ya×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2−1));
• and
• Bki′=Bki+Bka×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• to thus replace the color values of the reference data with the corrected values.

A computer readable medium recording therein a color proofing program for improving the color reproducibility of printed matter to be produced by a printing press in proof print produced by a proof press by the use of a computer, the color proofing program instructing the computer to execute the processes of:

• creating a look-up table containing converted values of image data over the entire color space with respect to the proof press;
• correcting the look-up table based on the color of printing paper for the printing press and a paper exposed area factor in the proof print:
• creating proof print by the use of the corrected look-up table;
• in the case where the proof print is produced based on both of density gradation and area gradation and the colors of the printing paper for the printing press and a printing paper for the proof press are approximated to each other to such an extent as not to need to take the ink transmittance into account, the look-up table correcting process includes the processes of:
• specifying an influence range defining how far reference data is influenced in the color space when the color values of the printing paper for the printing press are added to the color space;
• and
• determining an influence value for each of the reference data based on the color values of the paper and the value of the influence range, to thus add the influence value to the reference data.

A computer readable medium recording therein a color proofing program for improving the color reproducibility of printed matter to be produced by a printing press in proof print produced by a proof press by the use of a computer, the color proofing program instructing the computer to execute the processes of:

• creating a look-up table containing converted values of image data over the entire color space with respect to the proof press;
• correcting the look-up table based on the color of printing paper for the printing press and a paper exposed area factor in the proof print;
• creating proof print by the use of the corrected look-up table;
• in the case where the colors of the printing paper for the printing press and a printing paper for the proof press are different from each other to such an extent as to need to take the ink transmittance into account, the look-up table correcting process includes the processes of:
• determining corrected values (Ci′, Mi′, Yi′, Bki′) of color values (Ci, Mi, Yi, Bki) of arbitrary reference data I in the look-up table in accordance with the following equations when color values (Ca, Ma, Ya, Bka) of the printing paper for the printing press are added to a part where a paper exposed area factor is 100%, wherein address values (Cid, Mid, Yid, Bkid) express the color values (Ci, Mi, Yi, Bki) by N-bit:
• Ci′=Ci+Ca×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• Mi′=Mi+Ma×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• Yi′=Yi+Ya×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• and
• Bki′=Bki+Bka×(1−Cid/(2N−1)×Mid/(2N−1)×Yid/(2N−1)×Bkid/(2N−1));
• to thus replace the color values of the reference data with the corrected values.