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Color Calibration Charts
For CafePress Designers
See below for how to read the chart and why you need one.
Click an image to browse or buy products:
Charts on garments are full 10 x 10 inch image size.
[Solid Color Chart] [Spaced Color Chart]
Solid Color Chart
Best for color resolution checks
Spaced Color Chart
Best for color vs. background checks

How to read the chart:
[Color Chart Demo]

This is an RGB (Red, Green, Blue) color chart, showing all possible colors with a step size of 20 hex (32 decimal). For each primary color, there are 9 steps:

00, 20, 40, 60, 80, A0, C0, E0, FF hex.

There are 3 primaries with 9 steps each, so the chart holds 9 x 9 x 9 = 729 total colors.

You can quickly "read" the values for any color, once you know the system. Notice that there are 9 large squares. Each is a step in the Blue primary, as shown at top right:

Within each major Blue square is a 9 x 9 array with Green steps vertical and Red horizontal. The 00 Blue square is shown alone at right:

Examples of R,G,B values:
Bottom left is Black (00,00,00).
Top left is Green (00,FF,00).
Bottom right is Red (FF,00,00),
Top right is Yellow (FF,FF,00).

In the full chart at top, the top right is White (FF,FF,FF).
Within that FF Blue square, the top left is Cyan (00,FF,FF).
Bottom right in that FF Blue square is Magenta (FF,00,FF).


Why you need a color chart:

Simply put, the colors available as print pigments are not the same as those on a monitor. A monitor has a much larger possible brightness range, since it is actually emitting light. The light we see from a printed image depends upon the ambient illumination as well as the color reflectance of the pigments, which is only a fraction of the total incident light. This means that the print process has a smaller available color space... you can't get as many distinct print colors as you see on your monitor.

In addition, the colors on a monitor are formed by adding Red, Green, and Blue primary colors (RGB color). On a printed image, colors are formed by subtraction of Cyan, Magenta, and Yellow, as well as Black (CMYK color). So the print process has to map the original RGB colors to its internal CMYK system.

Also, printed images must deal with real-world chemical pigments. Different printing processes have different available pigments and hence different color palettes. So, the mapping of RGB colors from the original image to CMYK must take into account the specific available pigments as well as the reduced overall range. Since the target mapping has less possible colors than the original, a perfect mapping isn't possible. Setting the mapping is part science and part art; reasonable people can differ on what is the "best" mapping.

For example, the Heat Transfer process yields colors that are much more saturated than Direct Printing, particularly greens. The maximum RGB green (00,FF,00) from Heat Transfer appears much darker that you see on your monitor. Direct Printing gives a much lighter green than Heat Transfer, with subjective appearance more like the monitor... except that it also has a slight yellow cast.

However, absolute color is usually not as important as relative color, and here the difference in apparent brightness can translate into a big difference in color contrast. A thin black vein on a green leaf is barely noticeable with Heat Transfer, but it is very conspicuous with Direct Printing.

In addition, you may want your image to be printed on a colored garment. Will that green leaf even show up on a green shirt? If not, should you make a special version for green shirts, or avoid offering them entirely? Or maybe it will be fine with Heat Transfer but not Direct Printing... or vice versa. You might want to advise your customers which process to choose for a particular design on a particular color of shirt.

A related issue is that the "shorter" range of printed images means that detail is lost where there are subtle color changes... in some sections of the printed color chart you will find you can't see a difference among colors in certain regions. You may want to "punch up" the color curve to increase contrast and preserve detail.

Which brings us to the difference between the two chart styles. The colors are exaclty the same, but the divided chart has a white (clear) line between adjacent colors, where the garment color will show through. That makes it easy to see how any given color will show up against the color of the garment. The undivided chart, on the other hand, makes it easy to see if there is (or is not) a visible difference between adjacent colors where they meet.

If you are only going to get one type of chart, get the divided style if you are doing mostly line art. You will almost certainly be offering white garments, so get a Value T-Shirt (the least expensive), but get one with Heat Transfer and one with Direct Print. If you plan to offer colored garments, think about the cases that are most likely to offer problems, as in the above example of green leaves on a green shirt. There you'd want to get a Green T-Shirt using each process, but you could probably skip the other shirt colors.

If your designs tend more toward photos or realistic images, you might want the undivided chart style to evaluate color realism and contrast. This type of image tends to cover larger areas of the garment, so you are less concerned about how well a line stands out from the background garment color. You may not need to worry about that issue at all if you only offer white garments. However, if your image has lots of white in it and you are offering colored garments, note that (except for black garments) there is no white pigment... white areas just allow the background to show through. In that case, you may indeed want to go for the divided chart style. In either case, note that you still need to be prepared for the color differences between Heat Transfer and Direct Print.

Happy designing, and best wishes in your CafePress venture!



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