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Color Management

Introduction:
Back in the days of black and white photography, no one worried about color. Sure you have different filters to cause specialized effects but that was it. Once color photography came around, you simply chose the type of film for the color effect you wanted to achieve. The photo lab understood the film that was used and knew how to develop it to achieve the results that you would expect.

With the introduction of digital photography, this all changed. All of a sudden there were discrepancies between the initial photo, image displayed on the the monitor, and the final print. Given the number of available cameras with varying recording sensor manufacturers, types and styles of monitors, and finally brands of printers, no wonder there is such a wide variation between images on one device vs. images on another.
 
ICC Profiles:
All film manufacturers label their film in order to tell the photo lab which channel to use to correctly develop the film. This label includes the manufacturers name, channel information, and film speed. The photo lab just looks at the film and processes it according to the label.

In digital photography, there is no such information provided. You must ensure that the images you decide to display or print contain the correct information (label) so that they can be shown or printed correctly. This is very important, given that each device in your digital workflow has its own color characteristics, which are defined by an ICC profile for that device. An ICC profile should also be attached to every image (Adobe RGB, sRGB etc.). This tells the device that is using that photo (be it a monitor to display, photo lab, home printer) how the colors within that image should be shown. If there is no ICC profile embedded in an image, most devices assume that it is in the default color space, usually sRGB. sRGB is generally not the best profile to use for photographers due to its small gamut.
 
Camera Profile:
Before you go out and start shooting, it is important to decide which color space to use in camera. The two most common color spaces are sRGB and Adobe RGB. The differences between the two and why you should use one over the other are discussed here. Most high end cameras also have the ability to shoot in RAW mode, with the option of converting to a color space of your choice during editing. Adobe RGB and sRGB are both used with the jpeg image format while RAW is a format on its own. More on that here.

It has to be noted at this point that images shot in any color space, also have to be shot using the correct white balance, otherwise colors will not appear natural. Using the correct white balance will ensure that a neutral grey in your shot will match a neutral grey displayed on a color calibrated monitor.
 
Monitor Profile:
In order for images to be correctly displayed on your monitor, it has to have a profile associated with it. A monitor should be calibrated every month using a hardware calibration tool. There are a number of such devices available and it is usually best to spend a fair amount of money here to ensure the best possible calibration. When choosing a calibration tool, keep in mind that CRT monitors are much better for displaying accurate colors than LCD's. However when a photographer is shooting in the field a CRT is out of the question. If you use both, check to see if the calibration too will work on both types of monitors. This will save you money down the road.

All of the available hardware calibration tools will come with their own instructions and usually a wizard that you can follow along with to calibrate your monitor. Typically the calibrations will generate a monitor profile, store it, and apply it as the default profile. Once this is finished, colors will be displayed correctly.
 
Printer Profiles:
If you send your images to a photo lab, ask what color space they prefer to use. In your image editing software, covert your image to that profile using the perceptual rendering intent (Photoshop). This will scale the existing color space to the output color space, rather than clipping colors. There are other rendering types available but perceptual is the safest to use.

If you print your images at home on an inkjet printer, you will need a specific printer profile. Most home inkjet printers come with a set of profiles already built in, all you have do it specify the type of paper and the correct profile is automatically used. There are hardware devices that can be used to create custom printer profiles, but they are expensive and generally excessive for home users. Calibrating a printer using these devices involves printing a vast amount of color patches and measuring their colors. The software then uses this date to generate a profile.
 
Final Thoughts:
Color management can be a very complicated topic to understand, but here is a simple list to follow to ensure that your colors always look good.
  • check the color space in your camera and use the correct white balance.
  • use a hardware calibration device to calibrate your monitor.
  • make sure that the program you use for editing your photos is "color aware" and uses your image's embedded profile to display it correctly.
  • for web output, your image must be converted to the sRGB color space. This is because 99% of monitors used to view images are not calibrated and display all images as if they were sRGB.
  • if you send your photos to a printing lab, converted to their color space to avoid problems.
  • if you print at home, use the correct paper and printer profile
  • all color space conversions should be done using the perceptual rendering intent.
If you have any questions or suggestions please feel free to contact me.

Cheers.

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