Layer Blend: why no additive blending?

[AnotherBoringNickname webforumsuser@macromedia.com]

I was slightly taken aback when I realized that Fireworks MX does not have an "additive" layer blend feature. It has "multiply" and variations thereof, "lighten" and "darken", but no "add" or "average".

So, what do I want? An additive blend feature! It shouldn't be that hard! In fact, I've been over to Macromedia Exchange and took a quick look around -- but I didn't find any additive or average blending techniques.

Am I the only person who is missing an additive blend? Photoshop has it!

P.S. yes, I tried a work-around...

Yes, I know, Fireworks does have a difference blend -- and one could (theoretically) do an additive blend using difference blends. The key is this equation:
A + B = -(-A - B)

that means if you set up layers this way:
"layer A" (normal)
"invert layer" (invert)
"layer B" (difference)
"invert layer" (invert)

then you should end up getting A + B, right?

WRONG! I use the process above and it didn't work. My two original images were gradient sweeps between green, black, and gray (the preset Emerald). My result looked mostly ok, but had some RED! Ok, so I admit it looked cool, but it wasn't mathematically correct. That's no good.

The culprit? I assume the problem comes from the "difference" blend! "The color with less brightness is subtracted from the color with more brightness." This is the problem. Mathematical subtraction can sometimes give you negative numbers, but Fireworks Difference Blending guarantees "positive" numbers -- because all legal colors must be positive!

[Linda Rathgeber]

"AnotherBoringNickname" [email]webforumsuser@macromedia.com[/email] wrote:

> I was slightly taken aback when I realized that Fireworks MX does not
> have an "additive" layer blend feature. It has "multiply" and
> variations thereof, "lighten" and "darken", but no "add" or
> "average".

There is probably another way to arrive at the result you want in
Fireworks. You just have to know how. How we can't say, because we don't
know what you want the end result to look like.


Linda Rathgeber
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Design Aid: 10-Palette Pack for Fireworks & Flash
[url]http://www.webdevbiz.com/graphics.cfm[/url]
Playing with Fire | [url]http://www.playingwithfire.com[/url]
Victoriana | Theme Pack 03 - Club | [url]http://www.projectseven.com[/url]
Team MM Fireworks Volunteer | [url]www.macromedia.com/go/team[/url]
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[AnotherBoringNickname webforumsuser@macromedia.com]

Have you really never seen an additive blend? I'll bet you have but maybe didn't realize it. What does this look like? See [url]http://www.pegtop.net/delphi/blendmodes/[/url]

Notice that Photoshop has many more blends than fireworks. I don't expect to have ALL of them -- but the most simple (ADDITIVE) definitely should make the cut!

---

Mathematically speaking I want this:
NewLayer = PreviousLayers+CurrentLayer
(for each pixel)

even better would be an "weighting function":
NewLayer = (PreviousLayers + CurrentLayer)*k

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If you want more info on how light-based color is additive (R+G+B=White and "no light"=black), see [url]http://www.pixelart.es/pdf/ARTICULOS/Colour%20Blending.pdf[/url]

This is different from pigment-based color, where the primary colors are different (R,Y,B) and their combination yields Black. No pigment = white.

This makes me wonder... is there any image-editing software that allows you to operate in "pigment-based color" mode, where you can mix colors like you would on canvas?

[Linda Rathgeber]

"AnotherBoringNickname" [email]webforumsuser@macromedia.com[/email] wrote:

> I don't expect to have ALL of them -- but the most simple (ADDITIVE)
> definitely should make the cut!

Here's the URL of the Macromedia Software Feature Request form.


Linda Rathgeber
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Design Aid: 10-Palette Pack for Fireworks & Flash
[url]http://www.webdevbiz.com/graphics.cfm[/url]
Playing with Fire | [url]http://www.playingwithfire.com[/url]
Victoriana | Theme Pack 03 - Club | [url]http://www.projectseven.com[/url]
Team MM Fireworks Volunteer | [url]www.macromedia.com/go/team[/url]
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