Illustrator CS "Additive" Blend?

[Ashton...@adobeforums.com]

Illustrator CS/WinXP

If I draw two overlapping circles, each shaded 50% grey, I can't find a blend mode in Illustrator CS that will make the overlapping region 100% black. Does one exist? The closest I can get is 'multiply', but this only gives me 75% grey in the overlapping area.

What I really want is an 'add' blend, where the value of the overlapping area is a simple addition of the two circles on either side.

CorelDraw 12 is able to do this with an 'add' blend mode, and Photoshop CS can do it with the 'linear burn' layer blend mode.

Is there any way I can do this in Illustrator CS?

[Harron_K....@adobeforums.com]

Color Burn should do it.

[Ashton...@adobeforums.com]

Thanks for the quick reply. You are correct, color burn does work for this simple case.

However, what I am really wanting to do is have more than two circles.

For example, if I have three circles overlapping now, and each is 33% grey, the area where all three overlap is not 99% grey if I use the color burn tool.

When I use the 'subtract' blending mode in CorelDraw, the central area is 99% grey, as the RGB values are simply subtracted in the overlapping area.

It appears that Photoshop's 'linear burn' will do the job in Photoshop, but Illustrator doesn't seem to have this mode.

All I'm after is a simple subtraction of color values in the overlapping areas, so, for example, if I had ten overlapping circles (each @ 10% grey), the area where all ten overlap is 100% black, where 9 overlap 90% grey, etc...

[Bert Philippus]

Hey Harron:

Gotta love posters like that.

"I want 2 overlapping circles, can you explain that to me?"

"Here you go!"

"Oh, that's great, but what I really want is THREE overlapping circles!"

"OK, here you go... <sigh>"

"Well, what I'm trying to do involves more like all the planets in the solar system..."

"BLAM!"

[Harron_K....@adobeforums.com]

There is no direct equivalent in AI, but you can get close.

Apply Multiply mode to the fill for the selected objects. Then, in the Appearance palette, apply Multiply mode to the Default Transparency layer.

It'll get you 93.73% K with three 33% K objects.

{Hey, Berto!}

[Ashton...@adobeforums.com]

> Gotta love posters like that.

I apologise for modifying my request after my OP. I assumed that what I was experiencing for 3 circles would also hold for two circles, which it did not. Sorry to waste the time of the original responder. My intention was to give as simple an example as possible.

Harron, thanks for the response. I tried what you said, and yes, I get much closer to where I want to be. The issue with this technique is that for example, if I have 5 circles all 20%K, my resulting shades are 20%K, 49%K, 79%K, 96%K and 100%K. I need to have 20%, 40%, 60%, 80%, 100%K. (as I stated before, I am looking for a technique that is scalable to N circles of 100/N %K shading).

If it's not possible for me to do a simple linear color addition (or subtraction as in this case) in Illustrator, I guess I'll admit defeat. I'd really like to avoid using CorelDraw though...

Thanks again for your responses.

[Harron_K....@adobeforums.com]

If it's not possible for me to do a simple linear color addition (or subtraction

as in this case) in Illustrator...

I don't know how to do it, but someone else might.

You're welcome.

[Ashton...@adobeforums.com]

> I don't know how to do it, but someone else might.

OK. It would be dead simple if Illustrator had a 'subtract' blend mode like Corel, but as it doesn't appear to, I think the solution (if there is one) will be a bit of a hack, and might not be as accurate as I would like.

I played with using combinations of multiply and color burn for the default transparency and objects, and the closest I managed to get (for my 5 circle example) was 20%, 40%, 70%, 96%, 100%K (using a multiply on the default transparency layer, and a color burn on the circles). Unfortunately, this isn't close enough for my final application.

Cheers.

[Harron_K....@adobeforums.com]

It would be dead simple if Illustrator had a 'subtract' blend mode like

Corel...

Agreed!

[Kdod]

<Ashton...@adobeforums.com> wrote in message
news:3bc29...@webcrossing.la2eafNXanI...

Just "flatten and ungroup" and make the piece black..........

[Kdod]

"Kdod" <kmha...@comcast.net> wrote in message
news:6-CdnesIEqGs7BXY...@comcast.com...

Dupilicate and 180 rotate.....unless I am completely lost here.....does this
make sense?
>
>

[ti...@adobeforums.com]

maybe just use the pathfinder tool and just expand them and manually apply the colors you need.

[Ashton...@adobeforums.com]

maybe just use the pathfinder tool and just expand them and manually apply
the colors you need

Unfortunately, the images (quite a few) I am working with are imported from another program, and have large numbers (>50) of overlapping circles, meaning that any manual work beyond a 'select circles, specify settings' is too time-consuming. Thanks for the idea though.

I have managed to tweak things upstream in my workflow so that this lack of linear blending is no longer an obstacle.

Thanks for the contributions to this issue. I guess what has come out of it is a feature request for a simple 'add/subtract' blend mode in a future version of Illustrator...

[Jacob...@adobeforums.com]

Ashton,

I guess what has come out of it is a feature request for a simple 'add/subtract'
blend mode in a future version of Illustrator...

Not unless someone posts it as a feature request form: <http://www.adobe.com/support/feature.html>

[ti...@adobeforums.com]

maybe do the work in CorelDRAW then save as PDF or whatever format that "MAY" retain what you need?