Image printing apparatus and image printing method
An image printing apparatus can print an image in which graininess is suppressed while using a color material of light blue. To achieve this, the color material of light blue satisfies the following condition. Δ L B ≧(Δ L C −ΔL B )>0 and Δ L B ≧(Δ L M −ΔL B )>0 Here, ΔL C represents a difference in lightness between cyan ink and a blank area, ΔL M represents a difference in lightness between magenta ink and the blank area, and ΔL B represents a difference in lightness between light blue ink and the blank area. Further, the color material of light blue satisfies the following condition. h C +( h (C+M) −h C )/2≦ h B ≦h M −( h M −h (C+M) )/2 Here, h C represents a hue of the cyan ink, h M represents a hue of the magenta ink, h (C+M) represents a hue of the image printed with the cyan ink and the magenta ink in the same amount, and h B represents a hue of the light blue ink.
1. An image printing apparatus for printing an image on a print medium by using a plurality of color materials including at least cyan, magenta, and light blue, the image printing apparatus comprising:
a print head to print a dot corresponding to each of the plurality of color materials according to a signal,
wherein
the color material of light blue satisfies:
Δ L B ≧(Δ L C −ΔL B )>0 and
Δ L B ≧(Δ L M −ΔL B )>0
where ΔL C represents a difference between lightness of the image printed on the print medium with the color material of cyan and lightness of a blank area in the print medium, ΔL M represents a difference between lightness of the image printed on the print medium with the color material of magenta and lightness of the blank area in the print medium, and ΔL B represents a difference between lightness of the image printed on the print medium with the color material of light blue and lightness of the blank area in the print medium; and
Δ L C <ΔL M and
h (C+M) <h B ≦h M −( h M −h (C+M) )/2
where h M represents a hue angle of the image printed on the print medium with the color material of magenta, h (C+M) represents a hue angle of the image printed on the print medium with the color material of cyan and the color material of magenta in the same amount, and h B represents a hue angle of the image printed on the print medium with the color material of light blue.
2. The image printing apparatus according to claim 1 , further comprising:
one or more processors which executes the following steps of:
generating a multi-valued density signal corresponding to each of the plurality of color materials; and
generating a signal for each of the plurality of color materials by quantizing each of the multi-valued density signals, the signal defining printing or non-printing of a dot on the print medium.
3. The image printing apparatus according to claim 2 , wherein, in a case where the multi-valued density signal corresponding to the color material of light blue represents a density between a highlight and a halftone, the signal defines printing or non-printing of a dot such that dots of the color material of light blue do not overlap each other on the print medium.
4. The image printing apparatus according to claim 1 , wherein the plurality of color materials further include color materials of yellow and black.
5. The image printing apparatus according to claim 1 , wherein the plurality of color materials are dye inks.
6. The image printing apparatus according to claim 1 , wherein the plurality of color materials are pigment inks.
7. The image printing apparatus according to claim 1 , wherein, in a gradation area from white to black through blue,
in a case of representing a tone of blue color, a printing rate of the color material of cyan and a printing rate of the color material of magenta are larger than a printing rate of the color material of light blue, and
in a case of representing a tone between blue color and white color, a printing rate of the color material of light blue is larger than a printing rate of the color material of cyan and a printing rate of the color material of magenta ink.
8. An image printing method for printing an image on a print medium by using a plurality of color materials including at least cyan, magenta, and light blue, the image printing method comprising:
a printing step of a print head printing a dot corresponding to each of the plurality of color materials according to a signal,
wherein
the color material of light blue satisfies:
Δ L B ≧(Δ L C −ΔL B )>0 and
Δ L B ≧(Δ L M −ΔL B )>0
where ΔL C represents a difference between lightness of the image printed on the print medium with the color material of cyan and lightness of a blank area in the print medium, ΔL M represents a difference between lightness of the image printed on the print medium with the color material of magenta and lightness of the blank area in the print medium, and ΔL B represents a difference between lightness of the image printed on the print medium with the color material of light blue and lightness of the blank area in the print medium; and
Δ L C <ΔL M and
h (C+M) <h B ≦h M −( h M −h (C+M) )/2
where h M represents a hue angle of the image printed on the print medium with the color material of magenta, h (C+M) represents a hue angle of the image printed on the print medium with the color material of cyan and the color material of magenta in the same amount, and h B represents a hue angle of the image printed on the print medium with the color material of light blue.
9. The image printing method according to claim 8 , further comprising:
a first generating step of generating a multi-valued density signal corresponding to each of the plurality of color materials; and
a second generating step of generating a signal for each of the plurality of color materials by quantizing each of the multi-valued density signals, the signal defining printing or non-printing of a dot on the print medium.
10. The image printing method according to claim 9 , wherein, in a case where the multi-valued density signal corresponding to the color material of light blue represents a density between a highlight and a halftone, the signal defines printing or non-printing of a dot such that dots of the color material of light blue do not overlap each other on the print medium.
11. The image printing method according to claim 8 , wherein the plurality of color materials further include color materials of yellow and black.
12. The image printing method according to claim 8 , wherein the plurality of color materials are dye inks.
13. The image printing method according to claim 8 , wherein the plurality of color materials are pigment inks.
14. The image printing method according to claim 8 , wherein in a gradation area from white to black through blue,
in a case of representing a tone of blue color a printing rate of the color, material of cyan and a printing rate of the color material of magenta are larger than a printing rate of the color material of light blue, and
in a case of representing a tone between blue color and white color, a printing rate of the color material of light blue is larger than a printing rate of the color material of cyan and a printing rate of the color material of magenta ink.
15. An image printing apparatus for printing an image on a print medium by using a plurality of color materials including at least cyan, magenta, and light blue, the image printing apparatus comprising:
a printing head to print a dot corresponding to each of the plurality of color materials according to signal,
wherein
the color material of light blue satisfies:
Δ L B ≧(Δ L C −ΔL B )>0 and
Δ L B ≧(Δ L M −ΔL B )>0
where ΔL C represents a difference between lightness of the image printed on the print medium with the color material of cyan and lightness of a blank area in the print medium, ΔL M represents a difference between lightness of the image printed on the print medium with the color material of magenta and lightness of the blank area in the print medium, and ΔL B represents a difference between lightness of the image printed on the print medium with the color material of light blue and lightness of the blank area in the print medium; and
Δ L C >ΔL M and
h C +( h (C+M) −h C )/2≦ h B <h (C+M)
where h C represents a hue angle on an a*b* plane of the image printed on
the print medium with the color material of cyan, h (C+M) represents a hue angle of the image printed on the print medium with the color material of cyan and the color material of magenta in the same amount, and h B represents a hue angle of the image printed on the print medium with the color material of light blue.
16. The image printing apparatus according to claim 15 , further comprising:
one or more processor which executes the following steps of:
generating a multi-valued density signal corresponding to each of the plurality of color materials; and
generating a signal for each of the plurality of color materials by quantizing each of the multi-valued density signals, the signal defining printing or non-printing of a dot on the print medium.
17. The image printing apparatus according to claim 16 , wherein, in a case where the multi-valued density signal corresponding to the color material of light blue represents a density between a highlight and a halftone, the signal defines printing or non-printing of a dot such that dots of the color material of light blue do not overlap each other on the print medium.
18. The image printing apparatus according to claim 15 , wherein the plurality of color materials further include color materials of yellow and black.
19. The image printing apparatus according to claim 15 , wherein the plurality of color materials are dye inks.
20. The image printing apparatus according to claim 15 , wherein the plurality of color materials are pigment inks.
21. The image printing apparatus according to claim 15 , wherein in a gradation area from white to black through blue,
in a case of representing a tone of blue color a printing rate of the color, material of cyan and a printing rate of the color material of magenta are larger than a printing rate of the color material of light blue, and
in a case of representing a tone between blue color and white color, a printing rate of the color material of light blue is larger than a printing rate of the color material of cyan and a printing rate of the color material of magenta ink.
22. An image printing method for printing an image on a print medium by using a plurality of color materials including at least cyan, magenta, and light blue, the image printing apparatus comprising:
a printing step of printing a dot corresponding to each of the plurality of color materials according to signal,
wherein
the color material of light blue satisfies:
Δ L B ≧(Δ L C −ΔL B )>0 and
Δ L B ≧(Δ L M −ΔL B )>0
where ΔL C represents a difference between lightness of the image printed on the print medium with the color material of cyan and lightness of a blank area in the print medium, ΔL M represents a difference between lightness of the image printed on the print medium with the color material of magenta and lightness of the blank area in the print medium, and ΔL B represents a difference between lightness of the image printed on the print medium with the color material of light blue and lightness of the blank area in the print medium; and
Δ L C >ΔL M and
h C +( h (C+M) −h C )/2≦ h B <h (C+M)
where h C represents a hue angle on an a*b* plane of the image printed on the print medium with the color material of cyan, h (C+M) represents a hue angle of the image printed on the print medium with the color material of cyan and the color material of magenta in the same amount, and h B represents a hue angle of the image printed on the print medium with the color material of light blue.
23. The image printing method according to claim 22 , further comprising:
a first generating step of generating a multi-valued density signal corresponding to each of the plurality of color materials; and
a second generating step of generating a signal for each of the plurality of color materials by quantizing each of the multi-valued density signals, the signal defining printing or non-printing of a dot on the print medium.
24. The image printing method according to claim 23 , wherein, in a case where the multi-valued density signal corresponding to the color material of light blue represents a density between a highlight and a halftone, the signal defines printing or non-printing of a dot such that dots of the color material of light blue do not overlap each other on the print medium.
25. The image printing method according to claim 22 , wherein the plurality of color materials further include color materials of yellow and black.
26. The image printing method according to claim 22 , wherein the plurality of color materials are dye inks.
27. The image printing method according to claim 22 , wherein the plurality of color materials are pigment inks.
28. The image printing method according to claim 22 , wherein in a gradation area from white to black through blue,
in a case of representing a tone of blue color a printing rate of the color, material of cyan and a printing rate of the color material of magenta are larger than a printing rate of the color material of light blue, and
in a case of representing a tone between blue color and white color, a printing rate of the color material of light blue is larger than a printing rate of the color material of cyan and a printing rate of the color material of magenta ink.