I am making a document in Adobe Illustrator the problem is I want to be able to print it in both monotone and color just visible fine, however for monotone the values of each element don't match, and I don't know how to do that. I tried copying the element's "S" and "B" values of it HSB to another elements but it did not work.





  • I spent 30 or so minutes on this and I am frustrated because it seems simple but I can't just figure it out. – MathCubes Jul 15 '18 at 22:51
  • Why not just make them the same color? Surely I'm missing something here – Zach Saucier Jul 15 '18 at 22:56
  • Why are you trying to do this in the first place? – Zach Saucier Jul 15 '18 at 22:57
  • @ZachSaucier So I have two colors in a document, Adobe Illustrator, That I want to make them have the same value, so that when I print them out on a monotone printer they look the same value of gray. – MathCubes Jul 15 '18 at 22:59
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    Again, why not just change their color to make them be the same color?? – Zach Saucier Jul 15 '18 at 23:02

I guess you cannot control how the document will be printed. People print it with what they happen to have. Someone prints it with BW laser printer, someone has colors.

When people print your document with random printers do not expect that they mix colors equally to greyshades. Office printers will do as they will. Actually you have no way to force them use the wanted CMYK values because office printers need RGB input altough internally (if color) they operate in CMYK. Your only way to control the result is to make a file that has same color in places which should have same greyshade.

I believe a professional printhouse wants you to give a proper greyshade print PDF prepared for their process, if you intensively enough demand consistent greyshades. Then it's up to you how you place the greyshades. I haven't met this situation.

Assuming that different printers will print colors as greyshades "right", you need still a compatible set of colors. You can make them in Photoshop or in any program which has HCL (hue-chroma-lightness) or CieLAB color mode by selecting one color and making from it variations with Hue adjustment.

The following image is in Photoshop. Color mode = Lab. The leftmost color is the original, others are made of it with Hue&Saturation dialog:

enter image description here

Those colors have equal perceptional luminosities and they will produce the same greyshades if they are converted to geyshades honoring the perceptional luminosities.

If we add a white stripe with blending mode Saturation over the image, we get constant greyshade:

enter image description here

This of course works only in Lab mode.

Let's convert it to RGB:

enter image description here

There's no sameness left. But the RGB values are still quite right. If we convert the RGB image to greyshade color mode, we get:

enter image description here

Making the mode change directly from Lab to greyshade would give a flat grey image.

Unfortunately in Lab mode is possible to produce unprintable colors, even colors which cannot be shown in RGB screens. Also in RGB is possible to make unprintable colors. Keep saturation levels far from the extreme. Preferably start in CMYK mode.

If you keep in Lab color mode the Gamut Warning ON, you see as grey those colors which do not fit in the selected proof color space (= usually the used CMYK printing method but you can also select RGB in custom proof color setup )

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  • Thanks for the time to answer. With HSL, Why when I only change the last value and only change the hue, it affect the value of the gray so that they aren't the same in Gray scale? That is at-least in illustrator and Inkscape that I tested it in. Is there something that I don't get about color theory because its seems so counter intuitive. – MathCubes Jul 17 '18 at 14:58
  • Thanks for taking you time to answer. I didn't knew something that seems to have a simple answer didn't. To me it's seems possible because I thought what was going on was simply it just remove the hue value and left the other values the same. Do you know what is exactly going on? – MathCubes Jul 17 '18 at 14:59
  • @MathCubes HSL is a mechanical transform from RGB numbers. There's no serious effort done to make visual brightness independent from H ans S. System named HCL or LCH (hue-chrom a-luminance) resembles HSL, but its L is based on human sight research and should be considered more accurate than HSL's L. I'm not sure how Adobe converts RGB values to a single greyshade number . GIMP has easy to find conversion formulas. See this: johndcook.com/blog/2009/08/24/… – user287001 Jul 17 '18 at 15:57
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    @MathCubes (continued) The mechanical transform from RGB to HSL can be seen here: rapidtables.com/convert/color/rgb-to-hsl.html HSL's L=the avg of highest and lowest RGB number. That really doesn't make L "the seen brightness". I believe Adobe's conversion RGB -> Grayscale succeeds better. (as said, I cannot see the formula in Photoshop manual) Some effort to get perceptual lightness right in RGB->Grayscale conversion makes it, of course, different than simply desaturating a HSL color. That's why you cannot pretend with saturation reduction what conversion to grayscale will result. – user287001 Jul 17 '18 at 18:24

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