# How to determine the equivalent opaque RGB color for a given partially transparent RGB color against a white background

I have found that reducing the opacity against a white background is a good way to find usable lighter and less saturated tints of a base color.

As an example take this picture of an orange color:

The lower row shows the variants. The percentages are the opacities.

Having a white background and reducing the opacity is good when I search good tints, but I like to use equivalent 100% opaque RGB colors in the final product.

How do I calculate or otherwise find the equivalent RGB numbers, when the RGB numbers of the base color and the opacity are already selected?

I have tried color picker, but in Illustrator it at least gives only the base color.

## Answer

Use formula Y=255 – P*(255-X) where X is a RGB number, P=opacity (0…1), Y=new RGB number which should give the same appearance with 100% opacity as X gives with 100p% opacity against white background.

The formula is the general opacity formula, only simplified for this special case – the partially transparent top layer is against pure white.

Note: the white background should be a white object, not the artboard white. White background object is color managed.

If you are in Illustrator and want to copy the color with the color picker, make a copy of the partially transparent object and rasterize it. Select white background in the rasterizing dialog. Now the color picker gives the color, no calculations are needed.

Attribution
Source : Link , Question Author : Jonas Praem , Answer Author : user287001