Out of Gamut Fix

Andy

So, sometimes, you get ka-razy colors that are just out of gamut, and won't print right. Our own Shay Stephens taught me a little trick that helped me fix the out of gamut blue and orange/yellow in this night shot:



I use Photoshop CS2's Gamut Warning (View>Gamut Warning) and it will paint grey blobs over the areas that won't print right due to being out of gamut:




So the trick, is really quite simple. First set-up a softproof of the output device - then perform gamut warning on the selected softproof. Do a new empty layer, set the blend mode to multiply, and grab a grey color on your brush, and brush over the area with a nice fat brush, feathered (soft edges). You'll actually see the gamut warning disappear. For the out of gamut yellow, I used a lighter shade of grey. All in, about 1 minute of work. I was going nuts trying different things, and then I hollered for Shay :bow

saurora

That's really cool. I just wish I could remember all this stuff when I need it! I'm sure I have a few out-of-gamut shots at home I should practice on! Seems simple enuf...:D

wxwax

Cool tip. Must print more.

gluwater

Great tip Andy, I mean Shay. I bet this will be awsome to use on Macro where I always seem to have out of gamut colors.

BinaryFx

By default the gamut warning is tied to the CMYK working space, so if your output is a wider gamut inkjet - you may be proofing the wrong device! Gamut warning is a legacy setting that still uses legacy behaviour, so it can be a little confusing for many users of later versions that do not have the grounding from early versions.

First set-up a softproof of the output device - then perform gamut warning on the selected softproof.

Hope this helps,

Stephen Marsh.
http://members.ozemail.com.au/~binaryfx/

Andy

BinaryFx wrote:

First set-up a softproof of the output device - then perform gamut warning on the selected softproof.

Hope this helps,

I had done this, but it's a great point to not leave out of the steps. Thanks!

BinaryFx

Andy wrote:

I had done this, but it's a great point to not leave out of the steps. Thanks!

Not a problem Andy - glad to be of help in bringing up this point, using gamut warning is pointless if one is using the wrong warning!

Of course, before undertaking this work - it may be helpful to do actual output tests, comparing your regular workflow that does not include correcting out of gamut colours, against one that does. Gamut warning is only as good as the profile used for proofing and it is often a very subjective thing to evaluate.

What you mention is one common approach to Out of Gamut (OoG) issues, correcting a dupe or via non destructive methods for a specific output condition - usually affecting hue, saturation and or luminosity to bring the OoG detail into better shape for the soft-proofed output device. This attempts to reduce/remove the issue before conversion.

Another approach is to simply use perceptual rendering (if the printer output profile contains this table, common working space profiles do not) - this will compress the wider gamut into the smaller output space.

Then there are post conversion methods that can be used. One may perform a relative colorimetric conversion, clipping OoG colours and then to blend in a second perceptual conversion over the top of the relcol conversion, to add back missing detail that was clipped. In theory perceptual offers a better conversion, but often relative colorimetric does a better overall job (apart from detailed OoG areas)...so one can combine both methods in one file using layers, masks, blend if options and or blending modes.

Another approach is to use channel blends from the original file into the final conversion, to add variation and detail that may be lost in the original conversion.

One can combine all of these pre/post conversion methods, it can become an endless process!