Overlapping single colour layers

James McNangle wrote:

I want to compare two similar shapes, and would like to put masks of each shape on separate layers, with each layer coloured in a single primary colour, and overlap the layers in such a way that both colours are printed where the two shapes overlap, but only the corresponding colour is printed where one shape is larger than the other. As far as I can see, the only way to do this is to give the top layer of 50% transparency, making its colour diluted.
Is there a way to print both colours at full intensity?

James McNangle

Not sure what you’re after but have you tried the Blending Modes? Top of the Layers palette "Mode". Set upper layers to Multiply or Overlay for instance at 100% Opacity.

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"James McNangle" wrote in message

I want to compare two similar shapes, and would like to put masks of each shape
on separate layers, with each layer coloured in a single primary colour, and
overlap the layers in such a way that both colours are printed where the two
shapes overlap, but only the corresponding colour is printed where one shape is
larger than the other. As far as I can see, the only way to do this is to give
the top layer of 50% transparency, making its colour diluted.

Play with layer modes. You might try Screen first.

James McNangle wrote:

I want to compare two similar shapes, and would like to put masks of each shape on separate layers, with each layer coloured in a single primary colour, and overlap the layers in such a way that both colours are printed where the two shapes overlap, but only the corresponding colour is printed where one shape is larger than the other. As far as I can see, the only way to do this is to give the top layer of 50% transparency, making its colour diluted.
Is there a way to print both colours at full intensity?

Sure,

set:
Background: white
Layer 1: Solid color with shape 1 as layer mask: 100R 0G 0B

Layer 2: Solid color with shape 2 as layer mask: 100R 0G 100B (= M!); Layer Mode of Layer 2: Difference

Layer 3: Selective color adjustment layer with blues adjusted to: -100C -100M +100Y

This gives you red and green as the colors of the shapes without overlap and yellow (R + G) in the overlapping area.
With proper adjustments every combination of primaries is possible. The layer masks should be sharpenend to minimize black dots at the boundaries as far as possible. For a final printout, merge down and blur slightly in order to prevent jaggies.

HTH, Peter

edjh wrote:

James McNangle wrote:

I want to compare two similar shapes, and would like to put masks of each shape on separate layers, with each layer coloured in a single primary colour, and overlap the layers in such a way that both colours are printed where the two shapes overlap, but only the corresponding colour is printed where one shape is larger than the other. ….

Is there a way to print both colours at full intensity?

Not sure what you’re after but have you tried the Blending Modes? Top of the Layers palette "Mode". Set upper layers to Multiply or Overlay for instance at 100% Opacity.

Thank you for this suggestion. I put some diagrams showing what I was trying to achieve on my web page, before I read your suggestion. These are shown at http://www.corybas.com/Overlays.htm. ‘Multiply’ gives the effect I was looking for. I am not sure what ‘Overlay’ does, but it doesn’t give this effect.

James McNangle

"James McNangle" wrote in message

Thank you for this suggestion. I put some diagrams showing what I was trying to
achieve on my web page, before I read your suggestion. These are shown at http://www.corybas.com/Overlays.htm. ‘Multiply’ gives the effect I was looking
for. I am not sure what ‘Overlay’ does, but it doesn’t give this effect.

It would be easier if you used the RGB model.

James McNangle wrote:
….

Thank you for this suggestion. I put some diagrams showing what I was trying to achieve on my web page, before I read your suggestion. These are shown at http://www.corybas.com/Overlays.htm. ‘Multiply’ gives the effect I was looking for. I am not sure what ‘Overlay’ does, but it doesn’t give this effect.

Seeing what you actually want, the solution is quite simple:

RGB model, white Background
Layer 1: shape with 255 R 255 G 0 B; mode = Normal
Layer 2: shape with 255 R 0 G 0 B; mode = Difference
Layer 3: shape with 0 R 255 G 0 B; mode = Difference;
that’s all

BTW, IMHO you have a misconception of "adding" colors. You want the colors to subtract, not to add! CMY are the subtractive primaries and black represents zero luminosity.

Peter

(Peter Wollenberg) wrote:

……….

Seeing what you actually want, the solution is quite simple:
RGB model, white Background
Layer 1: shape with 255 R 255 G 0 B; mode = Normal
Layer 2: shape with 255 R 0 G 0 B; mode = Difference
Layer 3: shape with 0 R 255 G 0 B; mode = Difference;
that’s all

BTW, IMHO you have a misconception of "adding" colors. You want the colors to subtract, not to add! CMY are the subtractive primaries and black represents zero luminosity.

Thank you for your interest. I know what you mean about colours adding, but for me school paints came first, so I normally think blue plus yellow equals green, etc.

To try to get a better idea of what was going on, I set up three experiments.

1. I set up a new file, white background and RGB colour mode. Then I created three overlapping circles on separate layers, set each layer to ‘Difference’, and coloured them respectively 100% red, green and blue. Rather to my surprise, each layer came up as the complementary colour, but these combined as I expected, with true black in the middle. However the individual colours appeared rather desaturated compared with the following experiments.

2. I set up another new file, as before, but this time I set each layer to ‘Multiply’, and coloured them 100% cyan, magenta and yellow. This looked much the same as the first diagram, except that the individual colours appeared more fully saturated, but the black in the middle was less saturated.

3. I set up a third new file using CMYK colour mode, and used the same arrangement of layers as in experiment 2. This time the black was fully black, and the reds greens and blues appeared stronger than in experiment two.

When I sampled the colours in each region of each image, I found that in experiment 1 the primary colours were each 100% of the opposite two colours (ie the nominally red region was 100% green and 100% blue), the secondary colours were 100% of a single colour, and the triple colour was true black.

In experiment 2 each region was the appropriate combination of C M & Y, but these were achieved by various combinations of R, G & B, but generally at significantly less than 100%. This made the single and double colours appear more saturated than in experiment 1, but the triple colour had quite large percentages of R, G., and B, so that it was really a dark grey.

In experiment 3 (with the CMYK colour scheme) the double and triple colours had significant components of K. In particular the triple colour had 90% K, and R,
G., and B were all zero.

When I used the techniques of experiment 2 for an actual test case, I found that it did not work nearly as well as I had hoped, because I tended to see the overlap region as a separate shape, so that was difficult to visualise the two shapes I was actually comparing. So now I am wondering about alternative ways of achieving a similar result. I suspect I might do better if I drew constant width outlines around each shape, in different colours, and only displayed the outlines.

Anyone know a good way to draw a constant width outline around an irregular shape?

James McNangle

Layer effect>stroke

"James McNangle" wrote in message

(Peter Wollenberg) wrote:

………

Seeing what you actually want, the solution is quite simple:
RGB model, white Background
Layer 1: shape with 255 R 255 G 0 B; mode = Normal
Layer 2: shape with 255 R 0 G 0 B; mode = Difference
Layer 3: shape with 0 R 255 G 0 B; mode = Difference;
that’s all

BTW, IMHO you have a misconception of "adding" colors. You want the colors to subtract, not to add! CMY are the subtractive primaries and black represents zero luminosity.

Thank you for your interest. I know what you mean about colours adding, but for
me school paints came first, so I normally think blue plus yellow equals green,
etc.

To try to get a better idea of what was going on, I set up three experiments.

1. I set up a new file, white background and RGB colour mode. Then I created
three overlapping circles on separate layers, set each layer to ‘Difference’,
and coloured them respectively 100% red, green and blue. Rather to my surprise,
each layer came up as the complementary colour, but these combined as I expected, with true black in the middle. However the individual colours appeared rather desaturated compared with the following experiments.
2. I set up another new file, as before, but this time I set each layer to ‘Multiply’, and coloured them 100% cyan, magenta and yellow. This looked much
the same as the first diagram, except that the individual colours appeared more
fully saturated, but the black in the middle was less saturated.
3. I set up a third new file using CMYK colour mode, and used the same arrangement of layers as in experiment 2. This time the black was fully black,
and the reds greens and blues appeared stronger than in experiment two.
When I sampled the colours in each region of each image, I found that in experiment 1 the primary colours were each 100% of the opposite two colours (ie
the nominally red region was 100% green and 100% blue), the secondary colours
were 100% of a single colour, and the triple colour was true black.
In experiment 2 each region was the appropriate combination of C M & Y, but
these were achieved by various combinations of R, G & B, but generally at significantly less than 100%. This made the single and double colours appear
more saturated than in experiment 1, but the triple colour had quite large percentages of R, G., and B, so that it was really a dark grey.
In experiment 3 (with the CMYK colour scheme) the double and triple colours had
significant components of K. In particular the triple colour had 90% K, and R,
G., and B were all zero.

When I used the techniques of experiment 2 for an actual test case, I found that
it did not work nearly as well as I had hoped, because I tended to see the overlap region as a separate shape, so that was difficult to visualise the two
shapes I was actually comparing. So now I am wondering about alternative ways
of achieving a similar result. I suspect I might do better if I drew constant
width outlines around each shape, in different colours, and only displayed the
outlines.

Anyone know a good way to draw a constant width outline around an irregular
shape?

James McNangle

"KatWoman" wrote:

Layer effect>stroke

Thank you for this. It has some tricks to it, but it can be persuaded to work.

To allow the shapes to overlap transparently you have to set their mode to ‘difference’, then fill them with black. If you try to delete the contents of the layer, the border gets much wider, with gaps at 90°. And if you try to select the object and then move it, the border doesn’t move.

Also, although the layer is in ‘difference’ mode the borders aren’t, so where they overlap the top one obliterates the lower ones. The only way I can see to overcome this, if it matters, is to put each shape on a different page, put a border on it and fill it with white, so that only the border shows. Combine the layers so that all the layer information is lost, then copy all the shapes to a new page, so that the individual borders becomes separate normal layers, which you can then define as ‘difference’. The border colours would be inverted in the process so you would have to correct for this somewhere along the line.

James McNangle

James McNangle wrote:

"KatWoman" wrote:

Layer effect>stroke

Thank you for this. It has some tricks to it, but it can be persuaded to work.
To allow the shapes to overlap transparently you have to set their mode to ‘difference’, then fill them with black. If you try to delete the contents of the layer, the border gets much wider, with gaps at 90°. And if you try to select the object and then move it, the border doesn’t move.
Also, although the layer is in ‘difference’ mode the borders aren’t, so where they overlap the top one obliterates the lower ones. The only way I can see to overcome this, if it matters, is to put each shape on a different page, put a border on it and fill it with white, so that only the border shows. Combine the layers so that all the layer information is lost, then copy all the shapes to a new page, so that the individual borders becomes separate normal layers, which you can then define as ‘difference’. The border colours would be inverted in the process so you would have to correct for this somewhere along the line.

Better use "Stroke" as a layer effect on your shapes and not Edit-> Stroke.

Peter