Troubleshooting color

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This reserved article originally appeared in CHROMiX ColorNews Issue 55 on June 25, 2014.

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Contents

Troubleshooting Color - Part One (Displays)


Here’s one of those articles that may not have relevance for you now, but it’s good to tuck it away for when you need it. This is a compilation of tips for how to diagnose the more common causes of color problems.

If you’re just about to file this article away for the day when you actually DO have a color problem, read the next few paragraphs at least. Some of this you should do now.

One of the best things you can do to prepare for the eventuality of a color problem is to take note of what you’re doing while everything is working great. Having the files and the settings to duplicate what you’re doing now, and some samples to confirm what it is that you like, is enough to solve half the problems you are likely to run into.

Backup your computer files regularly

Yes, I know… half of my readers are already saying “Yeah I really need to figure out how to do backups someday…” and they’ll never get around to it. For you who are too busy, I have the next points of advice:

At least make backup copies of your profiles and other vital files

Most RIPs will have a way to save your settings in configuration files or “environment” files or something of the sort. Locate where they are on your hard drive and copy them off to someplace safe on a different computer in another building at least. Printer drivers have presets which save the printer settings. The file location of presets are not so easy to locate on your computer, but give it a try or follow the next step:

Record your settings

Besides backups of your important files, it’s good to have a record of the actual settings you’re using. This does not have to be as tedious as it might have been back in the days of notepads and pencils. Today there are several screenshot capturing programs available, or even screen recording programs that can make it very easy and quick to capture the settings in your color programs. A video of you browsing through all the tabs in your RIP may not garner a lot of “Likes” on YouTube, but will be invaluable if your color suddenly starts going south. It does not have to be fancy or long. You just have to be able to look back and see what your settings were.

Save sample prints

When everything is looking good and you’re happy, print some of your favorite test images and squirrel them away in a refrigerator or freezer somewhere. If you don’t have any favorites, grab some common industry test images. You can start by looking here: ColorWiki Test Images
Storing them in a cool, dark place will ensure that they will look the same several years in the future.

Without a hard copy example of what your printing should look like, it’s easy to be fooled by poor memory. Humans are not very good at remembering specific shades of color. You could find yourself faced with a change of color, but you don’t have any samples of what you printed before, so you don’t really know if you’re truly “off” or what things should look like when you are “back to normal” again. I have seen people try to solve an *apparent* image quality problem by comparing against some ethereal memory of what they used to print before they replaced the (fill in the blank). For all they know their discernment may have gotten sharper with more experience over time, and the work they printed before wasn’t so good after all.

Now that you have some settings and sample prints to fall back on, let’s tackle the diagnosis of the color problem you’re facing today.

Displays

On the one hand, there seems like only one thing you can do to help the color on a monitor, and that is to calibrate and profile it. If that does not work, there’s not much more you can do. On the other hand, the *accuracy* of a display’s calibration is always open for dispute. The next question to ask after someone claims their monitor is producing bad color is “compared to what?” Our eyes will tend to “auto white balance” to whatever scene they are looking at, including the display you’re staring at 8 hours a day. So a monitor can be off-color and still appear correct to the eyes if you’re used to what it looks like. That’s why it’s good to have an instrument reading, or a physical image, or something solid to compare to.

It is known that most monitor calibrating colorimeters are designed for consistency, not for true color accuracy. You’d have to spend between $1000 for a DISCUS colorimeter and $10,000 for a Photo Research device to get true accuracy. Still, your average Spyder or i1 Display Pro will do a pretty good job of getting you consistent color you can depend on.

Check your settings

Typical color correction curves in a graphics card
Color corrections curves - something is wrong here

When it comes to solving your color problem, start by checking the settings you’re using when profiling. Display calibration should be set to reasonable values, as discussed in other newsletters ColorWiki Monitors Part Two. If you are trying to get a printer to match your screen, try the options in this article on Print to Screen matching: How to get my Printer to Match my Screen.

The above article describes the importance of setting the white point correctly. Both in color and in brightness, the white point of your monitor should match the white point of the paper you are trying match. If an image of a white house with snow in the foreground is coming out “too dark” when printed, well there’s just not much you could expect a printer to do to make that white paper any whiter. Instead it’s probably your monitor that is too bright.

If you have calibrated and profiled your monitor, and your settings are correct for your situation and are still getting bad color, try this:

One secret to troubleshooting anything is to swap out components one at a time to see which one changes things, makes them worse or better. Fortunately most of us have ready access to alternate monitors, cables and even a friend’s laptop if we ask nicely. See which switch gives you a change in the right direction and that will be a good clue to figuring out where the problem lies.

Next time I’ll cover some ideas about troubleshooting color on a printer.



Thanks for reading,



Patrick Herold

CHROMiX

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