copy/paste into a specific color channel

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2018-08-01 19:21:14

I have recently purchased Pixelmator Pro with hopes of transitioning away from Photoshop CS6. I'm wondering if it is possible to paste an image into a specific color channel of an RGB image. This is trivial in Photoshop and is an absolute must for me.

Example:

1) We obtain multple images using a microscope that is captured on a single channel camera (greyscaled). One image is captured from a green channel and another from a red channel. Both images are saved as individual grey scale files — the colors are psuedo color.

2) We then copy each single channel image and paste them into a specific channel of an RGB file. The green channel grayscale image is pasted into the green channel and the red channel greyscale image is pasted into the red change. This generates an overlayed image.

Currently, I cannot see a way to do this with pixelmator. I'm hoping someone can make a suggestion. While I appreciate all suggestions, please note that the layer approach mentioned in another thread is not a viable solution.

Thanks for the help/advise
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2018-08-01 21:26:23

...please note that the layer approach mentioned in another thread is not a viable solution.
OK, then. I'm guessing the method that doesn't work for you is this: viewtopic.php?f=12&t=15254

Kudos for searching through the archives!

Can you let me know where it misses? Because this (or something similar) would be what I would suggest based on your needs as stated. If I know where it misses I can try to see if there is another way that meets all your needs.

- Stef.
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2018-08-02 12:24:39

Thanks for the reply Stef.

I've been watching Pixelmator for several years (since Adobe went to the subscription model) and have hesitated on purchasing it because of this single issue.

The layer approach becomes impossible for me as I have protanopia (a version of colorblindness) and I cannot see the blended color between layers. This makes adjustments impossible using layers. Also, I'm not actually sure what it would look like with muliple panels (see image). I generate mult-panel figures and use the channel displays in Photoshop (presented in grey scle) to make color adjustments. Each channel might have a unique image. So, a 10 panel (each a layer) figure could potentially have 30 images if I use all three channels. The layer approach would not be practical from a workflow point of veiw and color complexity. Other applications could be used to help like ImageJ for the National Institute of Health, but I'm looking for a solution to something that is trivial in Photoshop.


Thanks again for any help.

Image
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2018-08-02 14:28:44

First things first, those are awesome images. Thanks for sharing.

I do have another idea which preserves layers as monochrome images but I think it's probably too cumbersome. I thought I'd share it anyway and let you make that call yourself.

For each image:
1. Add a layer above that contains a solid fill (red or green) with a blend mode of Multiply.
2. Put the two layers in a group with the blend mode of Screen.

So for each blended image, you end up with:
Group (Screen)
- Colour (Multiply)
- Image in mono.
Group (Screen)
- Colour (Multiply)
- Image in mono.

Example below (like I said, probably too cumbersome - if you want to see a mono layer to edit it, you have to turn off not only its colour filter but the other group that makes up the compound image.).
Image
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2018-08-02 15:21:29

Thanks for the idea.

That is an interesting approach to solving the problem. While it would work, cumbersome is certainly the appropriate description. A 10 panel figure would require 60 layers — a nightmare to keep track and a significant time investment to not only setup but edit. My lab makes a lot of figures and this approach certainly wouldn't be efficient.

I'm surprised that Pixelmator Pro doesn't offer the needed functionality regarding channels. It doesn't seem all that difficult to implement (says the non-programmer) given that individual channel level control is already built into the application. The other major limitation is that we often get pixel level shifts from the microscope between channel acquisitions. This requires that we move individual channels a pixel or two to maintain proper alignment.

Maybe this type of feature will be implemented in future updates, but for right now it looks like I'm out $60. I realize there is a demo, and I tried it when Pro came out. Then I saw channel control on the website again and thought it would do what I needed. The previous demo timed out so I just bought the app and hoped.

Thanks for the input. If anyone else has suggestions, I'd love to hear them.
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2018-08-03 16:12:29

Hi pix.

Something just occurred to me so I thought I'd post another reply (then I'll stop pulling on this thread, honest). It's an adaptation of the first method.

Pixelmator Pro's Color Adjustments and Effects are non-destructive. Once you have applied your red or green adjustment with a single click of a preset you can then disable the Channel Mixer to do your edits on the layer (which is now black-and-white again). After editing you can re-enable the Channel mixer (which will have kept your settings).

Three things to bear in mind:
1. If you edit any pixel directly (e.g. by painting on the layer), any Styles, Color Adjustments and Effects will be applied permenently to the layer. I don't think that this will affect you but I thought I'd bring it up just in case.
2. If you have the Channel Mixer red and green saved as presets remember to apply them before any other adjustments. A Color Adjustment preset will over-ride any other Color Adjustments you have made to that layer (including removing any adjustments you may have added).
3. To combine the red/green layers you still need the blend mode of the top one to be set to Screen.

This may be something you have already considered and rejected. If not, I thought you might want to have a look at it.

All the best.

- Stef.