Colors are the single most important aspect of a textile CAD. If we can't get the right color, we are not much better than ASCII production database.

If you know some other CAD systems, you may be accustomed to browsing through pages and pages of color atlases (different for each printer and print mode), or changing RGB sliders and printing ad infinitum. Without getting much closer to the right color. And with ever shorter deadlines, you simply can not afford to play the color game in this way.

So how do we get the right color?

Using colorimetry. All the colors are stored in device independent CIE Lab space, and all you need to do is enter three values that you read from a spectrophotometer. The screen and print colors are generated automatically based on device profiles. Using thousands of measurements and some mathematics, but you do not want to know that.

To give you an idea of or color accuracy: we get an average dE CIE Lab = 2.4 on Epson Stylus Photo 750/1200 for all of 1932 colors contained in PANTONE® TEXTILE. And you know that many of its colors are pretty much out of color gamut (area of printable colors) of any ink-jet printer.

In the following picture, you see the color editor with PANTONE® TEXTILE-paper palette loaded. Below are colors for warp (capital letters A-Y) and weft (small letters a-y), and the color editing area.

One of the unique features of ArahWeave is, that program gives you a feedback on the screen and print accuracy of the selected color. This is indicated with the dE values on the right side of the window. If it displays a dE less than 2, it means that you are within color gamut and that color is reasonably accurate. If you have a dE of 15, you know that you will not get the desired color. In this way you can at least warn your customer that this particular color is not correct, and attach a yarn sample to the printed fabric simulation. Note that the predicted dE is usually overly optimistic, since it represents the difference of the desired color and the color found by the color matching engine of ArahWeave. We did an experiment and printed out our simulation of all PANTONE colors, re-measured them and compared the predicted color with the actual simulated color. The dE was smaller than 2 for 92% of colors, and smaller than 3 for 99.5% of colors. There were no prediction errors bigger than dE 4. So you can be reasonably confident in the program's prediction.

To avoid any misunderstanding regarding color accuracy, you should understand the notion of color gamut.

One common mistake is to link the actual number of displayable colors with color accuracy. When we were making the transition form 8-bits graphics cards with 256 colors to 24 bits per pixel graphics card, we said we now have 16 millions colors at our disposal - in a sense - we can do any color we like. Surely, it was a big step forward, but it has nothing to do with color accuracy. Actually, we could have 16 millions levels of gray between black and white... We need much more for color accuracy - primary colors that have the most extreme values in CIE Lab space, then a method color mixing and which makes them as predictable and linear as possible. And finally, a method of finding the desired color out of those we can generate.

ArahWeave will find the best possible color, but it can not make a color, which is not within device's color gamut. In the following pictures, you can observe the gamut of two commercial color atlases and one ink-jet printer. Notice how the areas, which they cover are quite different. First group of colors represent a projection of L versus a, second is L versus b and third is a versus b. Since we want to reproduce them on the ink-jet printer, we can indicate out of gamut colors with a small point.

All measurements were executed using GretagMacbeth Spectrolino, D65 light, 2 degrees angle. Spectrolino is directly supported from ArahWeave - you do not need any additional software to use it.

The color gamut of all PANTONE Textile Color System® colors. Note that PANTONE colors are really a collection of colors without strict ordering in mathematical sense. In fact, some colors have very extreme out-of-gamut values, which makes them impossible to reproduce on any ink-jet printer, even on 6-color ones. The choice to include out of gamut colors still makes sense: PANTONE® TEXTILE is targeting the fashion market, where such extreme colors are actually used. We must know precisely what we want, even if we can not reproduce it on a ordinary ink jet printer.

The color gamut of all RAL© colors. You see that most of colors are within gamut of ink-jet printer. The equidistant arrangement of measurements confirm that RAL's color choice is really based on CIE Lab.

The color gamut of all colors printable on Epson Stylus Photo 750/1200, a 6-color ink-jet printer. Picture contains 5832 colors, which are basis for our printer's color profile. A careful observer will notice anomalies caused by under color removal and switch from light Cyan/Magenta to dark Cyan/Magenta. Note that the color gamut of ink-jet printer depends a lot on the printer driver. We have developed our own printer drivers, aiming for large color gamut and linearity in color reproduction. The supplied drivers, which we have examined, mainly aim for reasonable reproduction of screen RGB to printed output, and score poorly both on linearity and color gamut.

Competitive programs, which run under Windows, support all types of printers, since the driver is provided by the printer manufacturer. But the output of these programs is limited by the quality of the printer driver. So even if they create their own ICC profiles, to replace the factory provided one, which is usually of poor quality, they still can not escape the printer driver's limitations.