Can I adjust my printer to handle unprintable colours better?
In PPL, Photoshop and other software, you can choose how to deal with out-of-gamut colours (colours in the image that fall outside the printer's range of printable colours) using the Rendering Intent setting.
Perceptual aims to preserve the overall visual impression of colours in the image. Any out-of-gamut colours will be adjusted to the nearest printable colours, and other colours may then be adjusted to preserve the relationship between all the colours in the image. The problem is, if all (or nearly all) the colours in your image are in-gamut, the image might be desaturated unnecessarily, and saturated colours in particular can be significantly dulled.
Relative Colorimetric will adjust only colours that can't be printed, leaving other colours untouched. This may result in slightly less saturated colours, but (assuming that not too many colours in the original image are out-of-gamut) brightness values will on the whole be more stable than if you use Perceptual.
So a good strategy is to check how much of the image is out-of-gamut first, and if there is a lot in important areas of the image, use Perceptual. If few colours or few areas are out-of-gamut, then Relative Colorimetric will alter the image less.
If you opt to use Relative Colorimetric, consider enabling Black Point Compensation to adjust the tone of the image so that the darkest point in the image matches the darkest point of the printer's ICC profile. It should not be needed if you choose Perceptual, because Perceptual is black point and white point relative. It should also not be required if you're using Canon papers and the built-in ICC profiles, Canon says. The consensus, however, seems to be that Black Point Compensation should do no harm and could help you achieve richer blacks particularly if you're printing on very absorbent papers.
"The more you print, the more experience you'll gain," Keith concludes. "And if you can't get the results that you want for any specific image, then you might be better off switching to a different paper with its separate, unique ICC profile."