Printer Tip: Basic Color Management

March 29, 2011

Absolute Colorimetric should only be used when converting from a smaller color space to a larger one

First, what is a color space? Color space is a range of saturated colors that a device or file can embody. Various types of devices such as cameras, monitors, and printers all have different color spaces.

Here is an analogy so you better visualize how different color spaces are related and how to go from one color space to another. Color space is like a ‘home’ for the color in your files. If you have ever brought an image into Photoshop and it is “untagged RGB” then it is homeless and needs to be given a home. Some color spaces are larger than others. The Pro Photo color space, for example, would be like the mansion of color spaces. Adobe RGB is like your nice 3-bedroom home and sRGB would be your basic 2-bedroom apartment. Now, you may think that putting your files into a larger color space would automatically change your color. But, keeping with analogy as before, you can easily fit the space of the apartment inside the mansion without changing any of the furniture inside. In order to give your files better-saturated colors, you have to optimize them. Like putting an addition onto your apartment to create more space. Now onto profiles!

Profiles

An output profile is a mathematical description of a color space. Now what exactly does that mean? An easy way to think about profiles is to think about communication. Like I said earlier every device has a different color space and this is like speaking different languages. For this example, I’m going to use my monitor and printer. So, lets say my monitor speaks Spanish and my printer speaks French. How are they going to communicate with each other? They need a translator and that would be the job of a color engine. The color engine can be selected when converting profiles directly underneath the profile being selected. The most important thing to notice about a color engine, consistency is key. Pick one and stick with it.

So, when the translation is made with our two languages that is where our profile fits in. The profile is the Spanish to the French translation book used to create a complete understanding on both. Basically, a profile creates a mathematical equation for my monitor to communicate to my printer and produces as close to the same color as possible. That is why calibrating monitors is so important. So, now that we understand profiles, when should we assign them and when should we convert them?

Assigning Profiles

If you have ever brought an image into Photoshop and it comes in as Untagged RGB, then we must give the file a space to work in. This is when you want to assign a space such as Adobe RGB, for example. Now, if you open a file and it is already in a working space, you can first work on the file and optimize if needed. Then, you finish by converting to a printer profile in the Print Dialog.

Rendering Intents

Now, I am sure you are saying, “well, I got my color spaces and profiles, what is the correct Rendering Intent to select for my images?” Well, we can immediately rule out two of the rendering intents, Absolute Colorimetric and Saturation. Absolute Colorimetric should only be used when converting from a smaller color space to a larger one. For example, a lot of shooters capture their images in sRGB and if you want to increase the gamut or in other words, the saturated colors, convert to Adobe RGB and use Absolute colorimetric.

Rendering Intent in Photoshop

The other rendering intent to avoid is Saturation, which will not take into consideration any of the real photographic elements and should only be used on banners or signs composed of text and graphic art. The two rendering intents that you should test all of your images on are Relative Colorimetric and Perceptual. Relative is good for images with natural colors like skin tones and landscapes. Perceptual can be good for images with a lot of saturation or out of gamut colors, but once perceptual is applied you may want to bring up the saturation if you loose any bit of high saturated colors.


What should you be working with?

So, which color space should you be working in for Canon printers? You want to capture and work with images that are as close to your output device as possible. So, you have the ability to capture in Adobe RGB using your Canon Digital SLR cameras and you can print in a color space very similar to Adobe RGB with the image PROGRAF printers. So, when working with Canon printers, Adobe RGB is the way to go!

Image Optimization using Soft Proofing in Photoshop

  1. Configure Soft proofing
    1. Configure soft proofing options in Photoshop by selecting View < Proof Setup < Custom. Select the paper profile you created or downloaded. If you are using the print driver to automatically manage color, use the Adobe RGB profile. I’m going to go ahead and select my paper profile -- let's say we select 5100_PR300_HWSGP2_D50.icc, for example

 

  1. Enable Gamut Warning
    1. Now you need to enable Gamut Warning. Gamut warning indicates what areas of your photograph are out of gamut and thus cannot be printed. If areas of your image are out of gamut, the printer software will change the out of gamut color to one that can be printed. The problem with this is that the computer does this automatically, leaving you with no control over the situation.
    2. In order to be sure that your image will print properly, and that your adjustments are correct, turn on Gamut Warning. Click View < Gamut Warning. When enabled, any out of gamut colors will turn gray. If you have an sRGB image, and a good paper profile, the whole image will be in gamut.

 

  1. Increase Saturation
    1. In order to increase saturation and keep the image within gamut, go to “create a new fill or adjustment layer” and select Hue/Saturation. Click on the Edit drop down menu and select the color you want to adjust. For this image of the sunset, I’m going to select Yellow, Magenta, and Red, for instance. However, every image will need a different combination of Saturation compensation's for enhancing the color gamut.
    2. Slowly increase the saturation until you see the gamut warning gray areas, and then reduce the saturation slightly.
    3. Be careful not to overdue this and over saturate the image – even if it’s in gamut.

 

  1. Now you’re ready to print!

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