I was hoping for some assistance please.

I would like to process an image to only have the information in the blue colour channel - thereby eliminating the red and green colour information. I would then like to composite this with another image - then on this blue colour channel only layer; mask out various areas to reveal certain parts of the full colour image of the background full coloured layer.

I want to end up with an image which has sections of full colour, and sections which look a bit greyscale...but I want definite channel information eg, blue channel, not greyscale.

I just can't seem to do it. Is is possible? I can't seem to permanently delete the red and green channels on the channel pallette, nor can I seem to get Channel mixer to just leave the blue channel information.

Any ideas would be greatly appreciated.

Thank you,
Julie

to disable R and G channels on a layer:

double click the layer icon to open the "layer style" palette and untick R and G channels...

Thanks rovanpera for your reply, but I don't really want to use the colour channel as a blending option, I want to use an image with only the blue channel and then place it as a layer on a fully coloured image, then mask out and revela different areas.

For example - I want to take out all the red and green from an image so that just the blue information is left. The example scene is a boat on the ocean. I want to have the boat just with the blue channel so I can paint it later with paints. Therefore I want to put the just blue channel boat as a layer on the full coloured image, then inverse mask on the boat so that the final image is the 'blue channel only boat' on the full coloured ocean.

I just can't seem to get this happening.

Julie

Sorry, I don't get what is the effect you are after.

the blue channel is just a grayscale image. so do you want to use the grayscale information of the blue channel in a specific way?

Thanks Rovanpera.

Basically, I want to create an image which has some elements which are a greyscale determined with just the blue channel information, and the other elements which are full colour.

So a hypothetical example to illustrate would be a beach scene with normally coloured sand, and trees, and ocean, BUT... also having a greyscale boat which has been derived from a file which has only the blue channel remaining.

I want to then paint with watercolour and oils on the boat. Does that help explain what I am trying to do?

Therefore, I would like the ability to process an image so that only one channel is the resultant image. I just used the blue channel as an example with the boat example to explain what I would like to do - so you could have a rough visual in your mind.

In some of my images the information on the blue channel has the right tonality etc and I would like to use that as the 'greyscale' isolated object (say for example just the boat) after I use masks to isolate it on a composited image.

I have some other images where I like the resultant tonalities when I isolate and only have the green channel.

I could always go and create a greyscale image but if there is one already available in the file which I like and can use to paint over, I thought I would try it..... but I am having trouble doing it with my knowledge, hence my request.

Julie

I am not 100% sure but try this. Duplicate the layer. Click on the blue channel and choose duplicate. Select all and copy. Paste it into the composite image and insert a mask on the layer and paint. When I tried it the composite image was greyscale and when I painted on the mask the colour appeared.

like this? I have selected the red channel with channel mixer...

oops, I didn't save my masterpiece. anyway, the boat is now in grayscale on a colored background

Click to view attachment

Here's the procedure:

Make a duplicate layer of the Background by clicking on the Background and doing CTRL/CMD J. It is named Layer 1 by default.

Go to Image>Apply Image, select Layer 1 in the Layer dropdown (immediately under source). Select the Blue Channel in the Channel drop-down. Change the Blend mode to Normal. Make sure the Opacity is 100%. Click OK. You now have the Blue Channel as a layer above the Background. (ANY channel data is grayscale, but this layer has exactly and only the Blue channel data in it.)

Now add a Reveal All Layer Mask (Layer>Layer Mask>Reveal All) to this Layer 1, select your paint brush with the Foreground colour Black and paint the layer mask where you want the colour of the Background layer to show through.

Thank you to all those who have replied to help me.

I now have a couple of ways to do work with what I am experimenting with.

Mark, the procedure you outlined I have adapted so that instead of using the duplicate layer as the same image, I use another image (like double exposure images) to create the Layer 1, and then can have only one channel revealed on an object in one layer and paint the mask to reveal everything else, or inverse the mask just to reveal the single channel object.

Thank you sincerely. I waded through tutorials and feature guides ....and I was just stumped. What a generous supporting community is here at LL. I now have the technical skill to explore and experiment with my images.

Julie

Thanks Julie, glad it's working for you.