With the recent change in photography from film to digital, a whole new series of problems have arisen. The main misunderstanding is in the conversion of RGB files. As all digital cameras (and indeed scanners) work in RGB, prepress and production houses are used to receiving digital files in the CMYK format. These were converted on-the-fly by the scanner operator to a predetermined set of values. Most photographers have little knowledge of CMYK, when we shoot on film we are producing RGB images. As the photographers usually have no knowledge as to where and by what method their digital images will be reproduced I have always maintained that it is safer for the prepress or production houses to convert these images to CMYK settings that are appropriate for their job.
In an attempt to
to get better colour management the International Colour Consortium (ICC)
came up with a way of describing colours and a set of lookup tables that
were embedded into the digital file, this was called an
I CC profile (Windows call it an ICM profile). A monitor profile will
tell the computer that is opening the file what the settings were on the
computer that created the file, and adjust the colour rendition, on the
monitor, to match those settings. This way the image on your monitor is
as close as possible to the image, as seen, during capture. There are
profiles for RGB, CMYK, Spot colour etc. You first need to calibrate or
characterise your monitor. MONITOR CALIBRATION
Photoshop is the leading image editing software, sadly, very few people set it up correctly. They happily accepted the settings that Adobe have placed as standard. The main problem is Adobe's use of the sRGB colour space. This is a Microsoft profile and is designed to simulate the RGB colour gamut of the cheapest monitor available, you would only use this for web images. By using this profile you have seriously downgraded your high-end monitor, not to mention getting colour that sucks. Also in the profile setup you have the choice, when opening a file with a mismatched profile, of 1..ignoring, 2..ask when opening, or 3..convert on opening. Most people have the ignore box ticked, big mistake! By doing that you may speed up the opening of the file but you have now stopped the computer from using the I CC profile to display the colours in their correct hues. Converting the file in no way changes it, you can prove this by opening a file, converting it and then closing it. It will close immediately, if you have changed anything Photoshop would ask if you wanted to save the changes. The only changes to the file will be when you save it on your system, it will then save with whatever profiles you have on your system.
The other misunderstanding is by prepress houses who only work in CMYK, they think the RGB conversion is not important as they will be converting to CMYK. If you get the RGB wrong the CMYK then converts from those values, your colour is now on a downhill slide. I know this from experience, I photographed a whole catalogue and sent the images to the prepress house. I even warned them on the CD to convert the RGB images. A few days later, I received a very distraught call from my client saying the colour printing look awful. The prepress house immediately blamed the digital files from my camera. On going down and talking to the guys I found out that not only did they have the sRGB profile setup for their monitor, they did not convert the RGB files either. On showing them the error of their ways and converting the files correctly full colour was restored. Not only was embarrassing for the prepress house, it was expensive as they had to reprint the brochure. When I pointed out that I have mentioned this on the CD their answer was well we're converting to CMYK so the RGB is not important. I guess they learned a very expensive lesson that day. Sadly this scenario has repeated it's self a number of times with different people, that's why I have put this page here.
Setting up Photoshop with the correct monitor profile only takes a few minutes, and will make your life much easier. Below I have reproduced dialog boxes from both Photoshop 5 & Photoshop 6. Unless you have a really good reason (in which case you don't need to read this) use the Adobe 1998 profile, after all they wrote it for their program and the chances are they know a lot more about it you do. If you work in Colorsync then you must use AppleRGB.
I hope the 2 images below prove this point. Even with the Web's limited reproduction I'm sure you will be able to see the difference.
Go to file / color settings / RGB setting. Mac users will notice that the Gamma changes to 2.2. Thats O.K. leave it as is (trust me you won't move to the dark side with this change). White point at 5000k is correct but most people use 6500k. You will notice that the monitor has been profiled and that has been applied. In the profile setup The assumed profiles are as indicated. In profile mismatch handling use "ask when opening" for RGB as it is good to know this is happening. With CMYK & Grayscale use the profiles the file came with unless you have a good reason to change them. N.B. As Photoshop is an American program it installs S.W.O.P. CMYK settings. In Australia we use Euroscale, they are not interchangeable.
