# Re: [Gimp-developer] Icons for layer modes

```On 2009-10-01, yahvuu <yah...@gmail.com> wrote:
> Technically, these are diagrams where the x-axis is the bottom layer
> brightness
> and the y-axis denotes the top layer brightness. The brightness difference
> caused
> by the blending operation is then color-coded as described above.
> The full explanation is available at:
> http://yahvuu.wordpress.com/2009/09/27/blendmodes1/#brightness_diff```
```
Yet another idea: for most of "puzzling" layer modes the mode is just
a function F of two variables: "level in current layer", and "level L
in composite of layers below" (here "level" is the value of a
particular channel).  So for each value of "level in current layer",
one gets a *curve* applied to the "composite of layers below"
(essentially, I consider the effect of the mode when the current level
is a solid color).

Moreover, for most of the modes, F is linear in "level in current
channel" (or piecewise-linear on [0..128] and [128..255]).  So in this
variable, knowing F for very few values allows one to "reconstruct" F
for the rest of the values.  And it is not mentally hard to consider
simultaneously 3 graphs of 3 functions: F(20, L), F(128, L), F(245,
L).

So what about the following icon: take some background color in good
contrast with all gray20, gray128, and gray245.  On this back, plot
the graph of F(20,L) in gray20, etc.  One gets an icon with 3 graphs.

For me, it is going to be a much better visualization than "a
color-coded graph of a function of 2 variables".  But it is quite
probable that I'm not representative enough.  What do you think?

Yours,
Ilya

P.S.  One could also combine both icons (maybe even one layered on top
of another)...

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