Why Color Management?

[René Damkot]

Color Management

Definition:
Color management is a term that describes a technology that translates the colors of an object (images, graphics or text) from their current color space to the color space of the output devices like monitors, printers, ...

One word: Consistency.
Color management is about making sure that your images look the same on your screen, as well as on your friends' screen as well as on the print. Now as well as in a few years.

People see color. Machines (camera, computer, printer) see 3 numbers.
What are the difference or similarities here?

You might call a certain color "deep red", while a friend of yours would call it "kinda orangy-red". So, two names for the same color. Which is is?
Likewise, not all machines will name the same color with the same numbers:
Here's how this color is "called" in different color spaces:



Also, when you and that same friend get sent to buy a "green" T-shirt, you might get home with two different colored T-shirts.
Likewise, not all machines will display the same color if the same numbers are sent:
That's where color management comes in: It tells the machines what the numbers mean.




It does that with the help of ICC profiles.
ICC profiles "describe" a color space. They tell the machine what a certain number means.

ICC profiles are either a working space ("standardised" profile, describing a fixed range of colors) or a device profile (specific for your display or printer for instance).

Color management needs three legs to stand:

1. An image with an embedded icc profile;
2. A color managed application;
3. A device profile for the output device.

If one of these three goes missing, so does color management.

[René Damkot]

Color Spaces

Definition:
A color space is a model for representing color numerically in terms of three or more coordinates. e.g. The RGB color space represents colors in terms of the Red, Green and Blue coordinates.

1) Color space of the image.

This starts easy: The images come straight out of the camera with sRGB or AdobeRGB tag. If you shoot raw, you have even more choice for color spaces: sRGB, AdobeRGB, ProPhotoRGB, WideGamut RGB, or some others. We've seen in the examples above what a difference for the numbers it makes if another working space is used. So you can imagine what will happen if you (or the software) mess up here, and assume the wrong working space. (Numbers get a different meaning, so the colors are wrong)

So. Which is better? sRGB, AdobeRGB or ProPhotoRGB?

Easy answer: If you have to ask, use sRGB. Since sRGB provides the least chance of errors. Why? Read on:
sRGB has been around since 1999, and is basically "the average CRT screen". So it's (still) the standard on the WWW and for most printing companies. If an image doesn't contain an .ICC profile, chances are it's (meant to be) sRGB, and is often assumed to be sRGB by software.

Why use another color space then?
It might be a better choice: AdobeRGB for instance has a bigger Gamut: It can contain a wider range of colors (Not more colors, just more saturated colors.)
This means for instance that you can take an image of a landscape with very saturated fall colors, and maintain this saturation. In sRGB, some of the colors might be out of Gamut, and therefore will be clipped. (one or more color channels blocking up against the "wall" at either 0 or 255. It "wants to go" to either lower then 0 or higher then 255, but can't: You loose detail)

For quite a few types of images however, chances are that you will not be able to see a difference.

Whatever color space you use, remember that the computer only has 8 bits per channel to work with. That is 256 ^3 = 16.777.216 colors. While this might seem a lot (it is ), it still means that a larger color space has bigger steps between each adjacent color. So best practice is to use the smallest color space that fits the image content.

When doing big color / luminosity edits on 8bpc files, you might "stretch" adjacent colors too far apart: Two pixels get values too far apart, leaving a "gap" in the middle. This might lead to jagged transitions in gradients that should be smooth (banding) and creates "spikes" in the histogram. A dead giveway for improper editing.

To overcome that problem (mainly affecting even larger color spaces, such as ProPhotRGB), edits can be made in 16bpc. This provides (don't ask) 32768*32768*32768 = Plenty colors. Worth noting that ProPhotoRGB and WideGamutRGB should only be used in 16bpc.

[René Damkot]

2) Color managed software

Not complete, but most known:

• Photoshop
• LightRoom
• DPP
• Other Raw converters.
• Browsers: FireFox 3 when enabled, Safari, OmniWeb 5.1.3 (Mac), Microsoft EXPLORER (Mac), Flock 2.5 (with Firefox Color Management Add-on), Upcoming version of Chrome. (Not the current version)
• Anything Mac on OSX
• Just about nothing Windows on XP, limited on Vista.

If your software is not color managed, you'll see the difference between your monitor profile and the document profile. So the colors will be off by that difference.

3) Output profile

This will be a monitor profile or printer profile most commonly.

Let's start off with the monitor profile, since it's the most frequently used (anytime you use the screen ):

By default, your Mac or PC will have some profile installed.
Your job is to make sure this profile is an accurate profile. (It most likely isn't)

This "default profile" is probably wrong for several reasons:
It's targeted at the "average" home user. Who plays games, views movies, works with text, and might edit a photo. Also, most LCD screens are so bright they burn your retinas out of the box, so they need to be dialed down, or your prints will appear darker then your screen.

The best option is to create a monitor profile using a calibration device, such as an EyeOne Display, one of the various flavours of Spyders or a ColorMunki. The cheapest solution is a Pantone Huey. There are various methods of "calibrating" by eye, but I've never been able to get consistent results that way. YMMV.

Printer Profile: This profile is specific to your printer, the ink and paper used. Most paper manufacturers have .icc profiles available for download.
It's also possible to create "custom" profiles, using a calibrating device, such as a Spyder2Pro, Spyder3Elite (?), or a ColorMunki. This will ensure that the display is accurate and gives you the first step to get prints that match the display. It'll also ensure that what you see is the same as what other people with a calibrated screen will see.

Color management isn't that difficult. But as with all technical things: To err is human, but with the help of a computer you can create a REAL mess.

[René Damkot]

Some very common types of "user error":

• "Images look desaturated in a non color managed program (the wrong web browser) compared to PS".
  Probable cause: You are viewing in a non color managed program. The image is not in sRGB, but for instance in AdobeRGB. You are seeing the difference between your monitor profile and the image profile. Since AdobeRGB is likely to be much wider then your monitor profile, the colors will appear muted.
  
• "images look over saturated in a non color managed program (web browser) on my new wide gamut monitor"
  Probable cause: You are viewing in a non color managed program. The image is in sRGB. You are seeing the difference between your monitor profile and the image profile. Since sRGB is likely to be much smaller then your monitor profile, the colors will appear over saturated.
  
• "Images print a lot darker then they are on screen"
  Probable cause: Your monitor is too bright. Use a calibrator. Most common advise is to aim for a brightness of somewhere between 80 and 120 Cd/m^2 (depending on screen and ambient lighting)
  
• "Prints don't look like the monitor at all"
  Probable cause: Double managing of color (both PS and printer) or no managing at all.
  
• "Image doesn't look the same in AdobeCameraRaw and DPP / on camera"
  This is not a color management issue, but the difference in rendering between Adobe and Canon Raw converters. Choose a "Camera" profile in the ACR "Camera Calibration" tab.
  
• "image looks way too yellow in LR or PS, correct in other applications"
  Probable cause: Not user error, but a corrupted monitor profile.

More troubleshooting in the original "Color Problems?" thread, which is here.

[René Damkot]

Place holder

Please do not respond to this thread if you have a question: Create a new thread instead.

C&C for the thread is appreciated, I'll clean up later

[calvinnemail]

Great info! thank you.

[Paul Barrett]

Wonderful, succinct intro. Thank you!

[thanhnamtt2]

thankyou

[hugh650uk]

nice info! thanks

[aperturetrading]

calibrate your display/monitor to render your desired print output ^_^

[bsmotril]

Here is a really nice test page to see if your web browser is color managed by rolling over test images and looking for changes: http://www.gballard.net/psd/go_live_...Gprofiles.html

[cdiver2]

A interesting article that explains color space very well http://www.digital-photo-secrets.com...7c+Photo+Links

[QTran0320]

What do i send to the printing company for my color to come out as I would in my display?

Jpg, Tiff?? and with proof color turn on in photoshop and ymck color checked?

thanks

[xpfloyd]

Originally Posted by QTran0320

What do i send to the printing company for my color to come out as I would in my display?

Jpg, Tiff?? and with proof color turn on in photoshop and ymck color checked?

thanks

Im not sure if this happens with all printers but the one I use (Loxley colour) here in the UK have a downloadable colour profile for photoshop so that I can check the proof colours using their profile. It might be worth checking with the company you are using for something similar

[tonylong]

Originally Posted by QTran0320

What do i send to the printing company for my color to come out as I would in my display?

First off, have a monitor that is good and reliable with colors. A lot of consumer monitors and especially laptop monitors are, well, cheap and not good for high-quality edits and proofing.

Then, you can calibrate that monitor that "reads" your monitor tones and with software that will display specific tones, and then take the output of the device and will determine what corrections are needed and make the appropriate adjustments.

When done with the calibration the software will store a "profile" in the Look Up Table (LUT) of your graphics card, and will normally set up your system with that profile so that it can be loaded at startup.

Programs like Photoshop, Lightroom, Digital Photo Professional, Aperture, and I guess other photo programs can make use of that profile in giving accurate color renditions.

Also, it's important that you realize that consumer monitors are generally way to bright out of the box. The first thing I do with a monitor is to dial down the brightness!

Then, many print labs/services enable you to go one step further: they provide "profiles" that can instruct programs with "print proofing" as to how the printer/paper/ink would put out the image. So follow the instructions on where to store the profile, then you point the Proof Setup dialog to that specific profile. Don't use cmyk.

From there you will want to go through a process of working with your print provider, sending them photos that you have edited (including softproofing and adjusting where needed) and they can send you "proof" test prints. Evaluate, you are the judge, repeat the process as needed until you are confident in the results and that the results will be repeatedly good.

From there, be happy!

Jpg, Tiff?? and with proof color turn on in photoshop and ymck color checked?

As to jpeg or tiff, most print providers work with jpegs, use a high quality jpeg unless the print provider specifically asks for tiffs. And, like I said, don't use cmyk to proof for the prints. Use the profile provided by the print provider!

thanks

Hope we can help!