A bit more comlicated example, per Bob-...'s "Too Cyan..." example: If your print is too cyan, you want to do the wrong thing, which is to add more cyan. However, conventionally, we don't adjust cyan; you want to do the equivalent thing, which is to remove red. However, we don't usually handle red filters, either, so you jump to the equivalent of removing both magenta and yellow. Once you work with this a bit, these equivalents will become second nature. In the meantime, you might want to consult that diagram, with three overlapping circles, labeled red, green, and blue. The little section opposite red is cyan, opposite green is magenta, and opposite blue is yellow.
Hello, Mr. Bill. I have two sets of questions.

1)What does "filtering" connote? In other words, does the name of a colored filter designate the color that is being blocked or the color that is being allowed to pass through?

2)In the portion of your entry which I quote above, you mention that to block red light, you instead do the equivalent thing which would be to block magenta and yellow. To block magenta and yellow would assume that these two colors "mix" to create the red you are trying to block. Doesn't this assumption contradict the very fact that, in the additive system where light is concerned, magenta and yellow are secondary colors, which when combined, cannot form red (a primary additive), but rather form white?

Thank you.