How to create colors of the same Value that have different Chroma and Hue?

Question

I think this should be simple. Using the HSB color tab, I'm trying to create colored shapes of the same VALUE such that when I desaturate the image as a whole, the shapes disappear. But when I use the tab, and Place the image in Photoshop with a Hue and Saturation Adjustment Layer and set Saturation to zero, removing the color information, the shapes remain distinct.

I think I must be fundamentally confused about the interaction of these three variables: Chroma/Saturation must add to Value, thus these aren't independent variables.

So, is there a way in Illustrator of achieving my goal? Thanks.

johnm27994604 · Accepted Answer

Forgive me, but "do this in an RGB document" is not a workflow. No need to comment again. I'll keep working on it myself. And if I figure it out I'll post my solution.

By @johnm27994604

It won't work in CMYK. Period.

When defining your colors in HSB you are using a very large color space. In an RGB ocument those colors are preserved. In a CMYK document they get converted to CMYK the moment you lift your finger from the mouse button. This is a CMYK color space inside an RGB color space. There might be slight deifferences between this plot and the specific color spaces you are using, but basically this is it:

So you are difining something outside of the small space, it will automatically be moved to the inside and of course changed.

Next thing is that you are opening this in Photoshop (or placing, doesn't matter. I presume your Photoshop document is in CMYK as well. Trouble is that those blending modes work best in RGB. In CMYK they will work differently or not at all.

So good luck with your project. Maybe you want to read a bit about color and color management.

Works in RGB https://youtu.be/oN1yKAn9EO4

I finally got it to work, and yes, both docs, in Photoshop and Illustrator are set to RGB. You're right, when in Illustrator the Document Color Mode was set to CMYK, using the HSB sliders wouldn't stick. But I do need to learn more about color, particularly about how the warnings work (Out of Web Color Warning and Out of Gamut Warning)

The solution, which is imperfect, I think because of antialiasing, requires that the Brightness AND Saturation be equal, letting the Hue be the only variable. Which is interesting, because I thought these three would be independent variables, but Saturation and Brightness both affect to Value. Not sure why.

If you look at the gray png you can see the contours of the shapes. Which means that the antialiasing must be adding brightness or contrast, just a little. I see tutorials online for turning this off, so I'll have a look at these.

Thanks for your help!

johnm27994604 · Answer

ChatGPT has given me a method:

Open Adobe Illustrator and create a new document.
Select the Rectangle tool from the toolbar on the left.
Create a rectangle by clicking and dragging on the artboard. Set the fill color to a solid color of your choice.
Duplicate the rectangle by pressing "Ctrl + C" and "Ctrl + F" to paste it in front.
Change the fill color of the duplicated rectangle to a different solid color.
Ensure that both rectangles are the same size and position them so that they overlap.
With both rectangles selected, open the Transparency panel by going to "Window > Transparency."
Change the Blending Mode of the top rectangle to "Difference."
If the colors of the rectangles are not the same value, adjust the opacity of the top rectangle until the overlap color is a neutral gray.
Save your document and you're done!

By adjusting the opacity of the top rectangle, you can make the overlapping area appear as a neutral gray, indicating that both colors have the same value. This ensures that if you desaturate the image, both shapes will be the same exact shade of gray.

Sign up

To post, reply, or follow discussions, please sign in with your Adobe ID.

Sign in to Adobe Community

To post, reply, or follow discussions, please sign in with your Adobe ID.

Scanning file for viruses.

This file cannot be downloaded