Illustrator color picker fails to detect a web color

Question

I opened a new document in Adobe Illustrator CS5, which defaults to CMYK as a color mode. I imported a raster image, used LiveTrace with 6 grayscale colors, expanded, and saved as SVG, which changed the color mode to RGB (which I believe makes no difference, since it's only grayscale colors at this point). In the text, I replaced black in the plain text of the SVG to one web color and gray with a tint of that web color, where the opacity is proportional to the amount of gray. In the example below, I used 7B68EE for MediumSlateBlue. I opened the SVG file in Illustrator and the color picker shows 6666FF instead of 7B68EE; when I click OK, the color changes to 6666FF.

Here is the color picker pointed at the area with 7B68EE in the source SVG file:

And here are three images of the difference for this case. The SVG with fill="#7B68EE" in the plain text:

The same SVG after clicking OK in the color picker for color 7B68EE, which becomes 6666FF:

I am using macOS Mojave 10.14.6 and Illustrator CS5 15.1.0 (yes, I really am, I was able to make them play nicely).

Why does the Illustrator color picker show a web color such as MediumSlateBlue (7B68EE) as 6666FF?

Answer 1

With the 'Only Web Colors' option checked, the panel will approximate whatever value from the picker to a predefined list of web-safe colors: https://helpx.adobe.com/illustrator/using/selecting-colors.html

So, just uncheck the 'Only Web Colors'.

Answer 2

To build on Lucian's accepted answer: a web color is different from a web-safe color. MediumSlateBlue is 7B 68 EE and web-safe colors only use doubled characters in multiples of 3 (00, 33, 66, 99, CC, and FF). For Illustrator, "web color" means "web-safe".

Similarly, if you are in CMYK color mode, the color picker will approximate your web colors without telling you. For example, make a rectangle with #800000, double-click on the foreground color to go to the color picker, quit the dialog, and double-click again on the foreground color. The dialog shows #800000 the first time and #7F1416 the second time. Illustrator approximates #800000, which is not in the CMYK gamut, to one that is. See Why does Adobe Illustrator change my web colors? .