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Photoshop Tutorial: • Understanding Color • To RGB or not to RGB

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Greetings All,


This tutorial is designed to help Photoshop users understand the sometimes cryptic, often misunderstood Color Settings. It assumes you have a basic understanding of Photoshop and requires Photoshop 7 or later on either PC or Mac.


Let's Get Started!

First, begin by firing up Photoshop and choosing Edit - Color Settings. This will bring up the standard Color Settings window. For this tutorial, please click the "Advanced Mode" box in the upper left corner of the window.


Working Spaces.

The first (and most important) section of this window is the Working Spaces area. This is the nuts and bolts of color management in Photoshop. Here you make workflow critical decisions about how Photoshop displays color. Not only that, you are literally defining just how much color you get to play with. This may not seem important to the average user, but choosing carefully here makes the difference between good color management and nasty surprises down the road. Nasty surprises ALWAYS include your work looking different than what you designed.


First, let's examine the RGB space. You probably already know that RGB means Red, Green, Blue and essentially corresponds to the colors your monitor can reproduce. That's not really the end of the story though. RGB color spaces can vary greatly from one profile to another. Why choose one over the other? The answer is gamut. Gamut is the range (latitude) of colors available in a given profile. RGB gamuts tend to be much larger than CMYK gamuts, but some RGB gamuts are larger than others. HEY! Let's just rush out and pick the biggest damn gamut we can find!!! The more the merrier, right? Wrong. Ask yourself a very important question... what is the final purpose of my design? Is it for print? For video? For the Internet? For my own personal entertainment? Each of these questions requires a different color space to achieve the best results. I'll detail a few for you here.


sRGB - This is the most common gamut available. It closely represents the colors reproducible on most CRT monitors. Use this one if you are producing graphics for the Internet.

Apple RGB - Simulates the color gamut of most Apple monitors. Not used as much any more as many Mac monitors are no longer produced directly by Apple.

Adobe RGB - This is a custom RGB profile for Adobe programs. It is widely accepted in the print and digital graphics industry and represents a larger gamut than sRGB. Working in Adobe RGB but outputting for Internet may result in unwanted color shifts.

WideGamut RGB - Exactly like it sounds... a RGB color space that allows a wider gamut than Adobe RGB. Carefull, young Jedi... you'll end up making something with colors only YOU can see. Not advised for Internet work.

NTSC (1953) - This is the gamut you want to use for video production. It is a smaller gamut than most but represents accurately the color space of NTSC broadcast standards.


CMYK - C what I Mean? Y, because I said oK!

Why use CMYK at all? It's a smaller gamut and half my darn filters are suddenly grayed out!!! AUGGHHH!!! Ok, relax, there's a reason for CMYK that goes beyond what meets the eye. It helps if you understand that Photoshop has been an industry leader in print production design for ages. Originally Mac-based, it is now exactly the same on a PC and offers the same horsepower that Mac users have enjoyed for many years. What is CMYK? CMYK is the standard four-color printing inks used in print production. CMYK stands for Cyan, Magenta, Yellow and Black. Why did they name Black K? Maybe because B already stood for Blue? I dunno, go ask your mother. :P


Anyhoo, the CMYK color space is tricky indeed. It is important to understand that when using CMYK, your monitor has to "simulate" in RGB what your printer is going to produce in CMYK. That means that Photoshop has to secretly do a ton of work, instantly and behind the scenes on every single pixel on the screen to map it in and out of a CMYK workspace so what you see is (hopefully) what you get. Now, if you NEVER intend to have your work printed, then you can almost ignore this. Almost... I strongly recommend using US Web Coated (SWOP) as your default. That way, you're at least going to be in the same ballpark as a printshop. Incidently, Web Coated has NOTHING to do with the Internet... it's a term used for offset press equipment (SWOP=Standard Web Offset Press) and should not be confused with what your browser can display. A good gamut (imho) to use for CMYK is the Photoshop 5 Default CMYK. It's bigger than the SWOP profile and produces more brilliant colors.


It's Not Easy Being Gray.

Actually, it is. Gray gamut profiles are largely dependant on the gamma of your monitor. Gamma is closely related to the luminance (brightness) of your monitor and how RGB is blended to produce Gray. In theory, equal parts of RGB should produce shades ranging from pure white (255,255,255) to pure black (0,0,0) but this is not always the case. You should use a tool appropriate for checking the gamma of your monitor and select the appropriate gray profile to match. After that, forget all about it... chances are you'll never have to work in Grayscale again unless you're a professional printer type person.



Color Management Policies.

Moving down the window, you will now find yourself at the Management Policies area. This part is where you tell Photoshop what to do if a document comes in with a profile embedded in it already. More often than not, you'll want to convert RGB docs to your working space and preserve the embedded profiles of other color space documents. Photoshop can alert you to various situations it encounters if you check the available boxes. I'd rather know more than not know at all so I keep all three checked all the time.



Conversion Options.

Captain! The matter to antimatter converters can't take much more!!! Ok Scotty, relax and have a Scotch. This part isn't really a big deal and you shouldn't panic. It can be deceptively easy to screw yourself royally here though, so I strongly recommend at least a passing knowledge of the decisions you make.


Engine: First, the conversion engine. That's the bit of code in the background that does the pixel crunching when converting documents from one color space to another. If you're a diehard Microsoft fan, by all means choose Microsoft ICM (Internal Color Management) otherwise come play with the big boys and choose Adobe ACE (Adobe Color Engine). Mac users may have more options here... depending on your system-wide color management policies, you might want to set this to whatever you use for the rest of your Mac.


Intent: Now a bit of science, and we can go back to drinking Scotch with Scotty. Your intent is what determines how colors are actually mapped from one space to another. Generally, I use Relative Colorimetric. It tends to provide the most stable results. Perceptual color tries to keep the relationships between colors the same while not necessarily keeping the values identical. Basically, your document will look the same, but may not output what you had in mind. Saturation color is an intent I never use. It sacrifices the accuracy of your colors for making them "pretty". Screw that... if I want pretty I'll dang well make them pretty myself. Finally, Absolute color. This is a tricky one... you'll use it if color is mission critical and you spend a great deal of time working with Pantones and such. I recommend it if you have a Photoshop/Illustrator/Digital RIP workflow and do lots of mission critical color work. This one is about the hardest to set up properly, but the most rewarding in the end if accuracy is your goal.


Advanced Controls.

Desaturate Monitor Colors: This is a tough one to explain, which is probably why they call it "advanced". Essentially, when you start working in REALLY BIG gamuts (often provided by OEM manufacturers for their devices) you actually exceed the gamut of your monitor in a big way. Use this setting to "tone down" the saturation of your images. Like the warning says though... your output might not match. For standard Internet graphics, you don't EVER need to check this. No touchie, got it?


Blend RGB Colors: Depends again on what your final destination of your output is. For Internet, you can ignore this. For print production etc, you might consider trying this both ways and seeing which setting provides the most accurate monitor to output accuracy.



The Last Word.

Well congratulations... if you made it this far you probably are either twirling your finger beside your head or enjoying a slowly spreading grin as the lights go on in your head. Hopefully the latter... color management doesn't need to be difficult, but you can certainly make it so by making poor decisions with this panel. Once you have made a few settings to your satisfaction, I recommend saving them for recall later. You can try different "sets" and see what works for you! In the end, remember that although color is a pretty subjective medium, by taking an objective stance towards management you ensure accuracy and portability across your workflow!


Good luck and thanks for reading!!!



Phoenix :P

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CMYK stands for Cyan, Magenta, Yellow and Black. Why did they name Black K? Maybe because B already stood for Blue? I dunno, go ask your mother.

man you really have make some credits with such a loong post :)anyway in CMYK shortcut K stands for "Key" because in Offset printing maschine CMYK is a four color process of printing and often and almost always Black ink is printed last, as the ink that add contrast and realistick black to image... Because of that it's has "K" shortcut as "Key" or last color... :)

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