Is there any advantage in using one against the other. Material design guidelines have used Alpha values to signify contrast for fonts. I could not really find a reason for doing so(as compared to using absolute colour values).
2 Answers
When using an alpha value, the color you see depends on the color in the layer below the color with alpha value.
See the example below.
When using a black (#000000) with 50 alpha on a white background you will get the 'actual color code' #7F7F7F, but when you but a blue color behind it, it will influence the actual color code of the #000000 with 50 alpha. In that case it is #277160.
Developers (the ones I've worked with) prefer actual color codes because of this.
answered Apr 28, 2017 at 10:17
The Material design guidelines use opacity for readability and accessibility reasons. The example they use on https://material.io/guidelines/style/color.html#color-usability demonstrates the issue:
