Fill opacity influence on blendmodes?

T
Posted By
Trickster
May 5, 2005
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375
Replies
2
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Closed
I’ve been trying to find information on how fill opacity controls the different blendmodes, but all relevant topics seems to stop where it gets interesting :-S (note: I’m not asking about the general purpose of the Fill opacity.. I understand how it works with layer fx)

As you may or may not have discovered, the fill opacity slider have a different influence than the normal opacity slider.

But this seems only to be true for some blendmodes.
From my observations there’s a difference in the following modes:

Color Burn/Dodge
Linear Burn/Dodge
Vivid Light
Linear Light
Hard Mix
Difference

In the rest of the blendmodes it seems that Fill Opacity and normal Opacity controls is similar.

So the mysterious question is: why is there differences in the way Fill Opacity controls the blendmode?
Moreover, what I’m really interested in, is wether there’s a general pattern or system behind this behaviour?

It doesn’t seem to follow the blendmode categorizations or technical properties (is the mode symmetrical, assymmetrical etc. see http://www.pegtop.net/delphi/blendmodes/)

Is there anyone out there who knows the whats going on with blendmodes and fillopacity?
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N
neon
May 5, 2005
Trickster wrote:

I’ve been trying to find information on how fill opacity controls the different blendmodes, but all relevant topics seems to stop where it gets interesting :-S (note: I’m not asking about the general purpose of the Fill opacity.. I understand how it works with layer fx)
As you may or may not have discovered, the fill opacity slider have a different influence than the normal opacity slider.

But this seems only to be true for some blendmodes.
From my observations there’s a difference in the following modes:

Color Burn/Dodge
Linear Burn/Dodge
Vivid Light
Linear Light
Hard Mix
Difference

In the rest of the blendmodes it seems that Fill Opacity and normal Opacity controls is similar.

So the mysterious question is: why is there differences in the way Fill Opacity controls the blendmode?
Moreover, what I’m really interested in, is wether there’s a general pattern or system behind this behaviour?

It doesn’t seem to follow the blendmode categorizations or technical properties (is the mode symmetrical, assymmetrical etc. see http://www.pegtop.net/delphi/blendmodes/)

Is there anyone out there who knows the whats going on with blendmodes and fillopacity?
it’s my understanding based on experience and the ps manual & help that fill opacity affects pixels painted or shapes drawn on a layer. to quote: "Fill opacity affects pixels painted in a layer or shapes drawn on a layer without affecting the opacity of any layer effects that have been applied to the layer". in other words: fill opacity affects only pixels painted or drawn on a layer. seems pretty straightforward to me. or am i not understanding the question?
T
Trickster
May 5, 2005
Yeah well thats exactly what I didn’t ask 😉 … its straightforward as you say… try the following, then you’ll understand what I mean:

Create an image with two layers (two different photographies or something with good color variance and difference btwn the layers). *Don’t* put any layerstyles on any of the layers.

Set the foreground blendmode to one of the modes I mention (e.g. hardmix or difference),
now first check how the normal opacity slider affects the blending (it just lowers the opacity), then set it back to 100% and try the fill opacity in the same manner
now you’ll see that the lowering of opacity is quite different!

follow?

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