In Graphic Design & Desktop Publishing, Overprinting is the process of printing one color over another.
Your Background in your publication may be pure black and your graphic may also be pure black, and they both look the exact same on the monitor, but will print completely differently
Monitors can only display one color of black, RGB Black, which is R0 G0 B0 Black, as black as it can be made in RGB terms this is known as “Absolute Black” or RGB Absolute Black (0R, 0G, 0B)
“Plain Black,” or 100% black ink, also known as 100k ink for its CMYK Black Color Value (0C, 0M, 0Y, 100K)
When RGB Black is converted to CMYK, the color values change depending on applications.. in the ‘old’ Photoshop Industry standard, Absolute RGB Black becomes 63C, 52M, 51Y 100K, also known as “Rich Black”, Adobe RGB 1998 Color Profile, its RGB Absolute Black becomes CMYK C75, M68, Y67, K90
“Rich Black” is different mixtures of colors to create richer and different tones of Black which vary my mixture depending on program / standard
Other variations include “Cool Black” (60C, 0M, 0Y, 100K) and “Warm Black” (0C, 60M, 30C, 100K)
All of the above blacks are represented as R0 G0 B0 on the computer screen, so they all look the same on a computer monitor, but they all print differently
Black in Page Layout Software such as InDesign & QuarkXpress and commercial publishing programs is always represented as 100K Plain Black, which looks kind of brownish on our computer screens
“Registration Black” is used for Registration Marks, and has a CMYK value of 100C, 100M, 100Y, 100K, but also appears as RGB R0 G0 B0 on the computer screen
If a value is CMYK + Pantone 285, then the Registration Color would be 100C, 100M, 100Y, 100K, 100 Pantone 285.
Registration Black should not be used for any printing besides registration marks, because it lays down the most ink of any color, which causes many printing problems
Plain Black (100K) is great for text, but doesn’t look good for large spreads, backgrounds, or graphics..
To make Adobe RGB 1998 Color Profile Black match your Publication Black, Create a new color in your Publication Application with a CMYK value of C75, M68, Y67, K90
Potential Problems with Black in Photoshop is not having the right Black formula, so one thing you should always do is Create a copy of your work periodically in the CMYK color mode, then click on the “Info” Panel and drag your mouse around to the different black locations in your document and see if the Black all reads the same, C75, M68, Y67, K90, or one of your own design
Then go through and make sure all of your blacks in QuarkXpress or InDesign also read C75, M68, Y67, K90
You can create your own black, but your CMYK Percentages should not add up to more than 300% (C75%, M68%, Y67%, K90% = 300%)
C50 M50 Y50 K50 is another option for creating your own individual color
If you don’t match colors, you will have “Knock-out” or Color Blending from Overprinting, which is sometimes desirable, but not usually.. knock-out occurs when your color knocks out the color underneath it , because the color values are different
Knock-out is especially common when putting an image created in photoshop with Black colors, into a publication with the standard 100k Plain Black
Some Common Blacks:
- Standard black 0C, 0M, 0Y, 100K Normal black.
- Rich black 63C, 52M, 51Y 100K The ‘old’ Adobe Photoshop black.
- Photoshop CMYK from Adobe RGB 1998 C75, M68, Y67, K90
- Cool black 60C, 0M, 0Y, 100K Black with a bluish tone.
- Warm black 0C, 60M, 30Y, 100K Black with a reddish tone.
- Registration black 100C, 100M, 100Y, 100K Used for registration marks.
- ‘Designer’ black 70C, 50M, 30Y, 100K A dark slightly cool black.