Why are there different possibilities for active and inactive icons in material design?

Question

I'm really curious why there are different possibilities for active and inactive icons in here :

And here :

Therefore, I am confused in these two cases:

1- Inactive dark icon on a light background should have an opacity of 26% or 38%?

2- The inactive light icon on a dark background should have an opacity of 30% or 50%?

Answer 1

why there are different possibilities for active and inactive icons

As Material Design evolves, and specifications are updated inconsistently.

So, I got confused in these two cases

Since IMO is more a theme of color than icons, and because I don’t remember to see the tables in the second link, I would say that the second link is more relevant and sticks to it.

The design library design_tint_password_toggle.xml uses 54% and 38%, which also indicates that the second link is "correct."

For further reference, from 2016-11-09, these "correct" values ​​are:

• Dark theme
  • Active: 100% white icon on a dark background.
  • Inactive: 50% white icon on a dark background.
• Light theme
  • Active: 54% black icon on a light background
  • Inactive: 38% black icon on a light background.