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blend mode puzzle

Posted: 09 Jul 2018, 11:00
by Peter Wassink
i'm looking for a way to limit/mask/stencil a certain alpha range.
the alpha control FX was my goto tool but....alas....it falls short. its not possible to manipulate its range sufficiently enough, i can't flip it for instance...

this is what i need it for:

in a single color-shadow-layer with lots of alpha variation i need to bring down the opacity of the darkest pixels.
idealy i have a brush and where ever i paint over my layer it will bring down the opacity of the darker pixels(with less opacity) to a lower level
while at the same time leave the lighter pixels (with more opacity) as they are

inverse alpha diff blendmode-how.png
inverse alpha diff blendmode-v03.png
So a recap....
when you look at row 4

You start with the image on the left.. the dark part are pixels with low opacity(= little see through) and the light part being pixels with high opacity (=more see through.)
all pixels have the same RGB value only Alpha channel differs.

i want a brush that reduces the opacity of the darker pixels but not further than a certain threshold.
so that no matter how often i pass with my brush the pixels will not be made any more transparent than a certain valu.

it is the inverse effect of Alpha-diff blend mode (row 3)
Alpha-diff will not add aditional opaqueness to a pixel as long as the opaqueness value of the brush is lower then that of the pixels on the canvas.
i want to remove opaqueness from the pixels on the canvas ...unless they are already under the level of opaqueness of the brush. in that case they should not be made lighter but stay as they are.

Re: blend mode puzzle

Posted: 09 Jul 2018, 16:31
by Svengali
Peter,
Have you looked at FX>Color>Source? Not sure it will do what you want, but you have lots of alternatives for combining options: Source (+Speed Profile), Blending Mode, Opacity...

I've created a custom version in which I insert a variety of custom-created images in the Spare Buffer to modify/tweak the current frame...

Sven

Re: blend mode puzzle

Posted: 09 Jul 2018, 21:56
by Peter Wassink
Great suggestion Sven,

i will test around with this. Thanks.

Do you have an example of what kind of images you use in your customversion? i can't quite imagine what you mean.

Re: blend mode puzzle

Posted: 10 Jul 2018, 02:20
by Svengali
Peter Wassink wrote: 09 Jul 2018, 21:56 Do you have an example of what kind of images you use in your custom version? i can't quite imagine what you mean.
The custom FX is a renamed version of the SOURCE .bin ADDED to the Preset list with some predefined settings so I can directly load it when needed. I assign it to a button using the FX Stack Bin option, choosing the custom.bin name I'd just added to the list.

The source images I drop into the Spare Buffer are simple: full-frame-repeat patterns, textures or gradations which I've collected on line or which I create for a specific effect.

Sven