Posted: Tue Jun 08, 2010 4:01 pm
GCR stands for Gray Component Replacement. (Professional Photoshop 5th edition)
It is the base amount of black ink hitting the page in a press printed image.
To get your mind around CMYK you have to remember that the CMY are color complements to RGB; exact opposites....K is the Black ink...K is one of the stronger tools we have in color correction it is extremely useful as we will see in the coming weeks. K gives the image POP and fullness.
In press printing there are limits to the amount of ink you can put to a piece of paper under a given process. Let's say for discussion the limit is 120 to create an image you not only use CYM inks at various levels you also need to add black...the total of the inks cannot exceed 120 so you might have 20C 50Y 40M this leaves you with being able to add 10K to the mix to darken the shadows and make the overall colors richer.
You could add 3 to each color above to get the same 120 but the shadows would look flat and gray.
GCR gives you control over the amount of K adjustment you are applying to the image.
So the GCR value is dependent on the material you are printing on and the process the printer has chosen. You can almost always use Max Black in the class since we are not sending out to a CMYK profile for press printing.
Hope this helps...
Greg
It is the base amount of black ink hitting the page in a press printed image.
To get your mind around CMYK you have to remember that the CMY are color complements to RGB; exact opposites....K is the Black ink...K is one of the stronger tools we have in color correction it is extremely useful as we will see in the coming weeks. K gives the image POP and fullness.
In press printing there are limits to the amount of ink you can put to a piece of paper under a given process. Let's say for discussion the limit is 120 to create an image you not only use CYM inks at various levels you also need to add black...the total of the inks cannot exceed 120 so you might have 20C 50Y 40M this leaves you with being able to add 10K to the mix to darken the shadows and make the overall colors richer.
You could add 3 to each color above to get the same 120 but the shadows would look flat and gray.
GCR gives you control over the amount of K adjustment you are applying to the image.
So the GCR value is dependent on the material you are printing on and the process the printer has chosen. You can almost always use Max Black in the class since we are not sending out to a CMYK profile for press printing.
Hope this helps...
Greg