adobe cs — colour #01

colour management has come a long way in the last few years. there are still a lot of the old guard who are yet to update their knowledge, and a lot of young guns who are yet to gain it. here’s the first of a couple of posts about colour management in adobe creative suite.

in the olden days (about ten years or so ago) the recommended practice for dealing with colour images was to save at least three copies of a photographic image : one rgb for onscreen, one cmyk corrected for sheet offset, and one cmyk corrected for press (newsprint). the most pedantic operators saved a different correction/conversion for every output scenario their image was destined for (eg. three different papers might have three different output profiles). so, many copies of each image — a wailing and gnashing of teeth — madness reigned.

this was also the time when raster images destined for print were always saved as tifs, unless they had spot colours or clipping paths, then they were saved as eps because it was the only importable file type that could retain such information. but now, of course, you save all your print ready rasters in psd format (you DO, don’t you? … no? then you should).

but back to colour management … de rigueur nowadays is to save raster images in rgb and allow InDesign to do any colour management on the fly. what? blasphemy and anathema to the old guard! page layout programs are for page layout and imaging programs are for images and that’s that. but such contentions are now piffle. there are good reasons why the adobe software is now called creative suite — it’s no longer a bunch of separate programs — it’s now an integrated set with many things in common, including colour conversion algorithms.

so, here’s a little demonstration for the non-believers (click to enlarge) :
screen grab of four versions of one image in InDesign

that’s a screen grab of the same rgb psd placed in four separate InDesign files. each InDesign file is assigned a separate colour profile as indicated by the labels. these are the same four colour profiles that could be assigned permanently through photoshop but, by being assigned to the InDesign files, they DO NOT change the image file (psd) in any way — just the way it is interpreted by InDesign.

assigning a colour profile in InDesign is as simple as choosing convert to profile from your edit menu and choosing the appropriate profile from the relevant dropdown :
screen grab showing convert to profile menu and window with dropdown options

the difference between the four InDesign files is more obvious when we turn on separations preview (windows > output > ) and have a look at some of the numbers. here are the same four files with only the black plates showing (again, click to enlarge) :
screen grab of four versions of one image in InDesign — black plates only

the readings in the separations preview panel come from the black background — which is r0g0b0 in the psd. you can see that fogra 27 allows for a total ink limit (also known as total ink coverage or total area coverage) of 350% and a solid black, whereas swop only allows 300% with 90% black, and poor old newsprint is restricted to 220% and has to pull the black back to 71%. NOTE: these are the exact same numbers you’d get if you did a cmyk conversion of the psd in photoshop.

what does all this mean?
it means that a single image can be sent to multiple output types by simply changing the InDesign profile. you do not need a separate image file for each destination.

now, converting the file to an output profile is not strictly necessary if your final output is pdf — because the conversion can be done at export. but, as the first screen grab shows, doing the conversion gives you a better idea on screen of what your final output is likely to look like.

we’ll have a nice little chat about this topic some more in a future post.

til then, keep grunting.

• related post : InDesign tip : #24 : checking the black plate in separations preview.
• related post : adobe cs — colour #02 : you really need to get your shit together.
• related post : adobe cs — colour #03 : what’s the best colour profile?.

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One thought on “adobe cs — colour #01

  1. Pingback: mac IT pro » Blog Archive » Converting Adobe InDesign files to Black and White output

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