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How do I use a pixel layer containing a greyscale image as a layer mask so that white pixels show the current layer and black pixels hide the current layer, and grey shades in between represent partial transparancy?

In the screenshot (attached) I want to use the black and white picture of the skull to mask the green square so that I end up with a green skull where the white is, and the black are would be transparent. any grey pixels would be different levels of transparancy.

I really need step by step instructions as I just don't understand how to do this in AP as I am so used to doing it in Adobe Photoshop.

Thanks

ap-masks.jpg

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Go to the Layers panel, right-click the skull layer and choose ‘Mask to Below’ from the context menu.


Alfred online2long.gif
Affinity Designer/Photo/Publisher 1.7.3.481 • Windows 10 Home (4th gen Core i3 CPU)
Affinity Photo for iPad 1.8.2.174 • Designer for iPad 1.8.2.4 • iPadOS 13.3.1 (iPad Air 2)

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17 minutes ago, Alfred said:

Go to the Layers panel, right-click the skull layer and choose ‘Mask to Below’ from the context menu.

Hi, thanks but I tried that and it doesn't acheive what I am after. Instead it results in a green square instead of a green skull (see attachment).

I suspect I either need to do something with channels or to create a selection from the greyscale image but cannot find how to do that :-(

ap-masks2.jpg

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I would invert the skull layer to make the skull black. Layer > Invert

skull1.jpg.01e61a82ba334c9d8e22d5bc710eb831.jpg

 

Put the green on top and change the Layer blend mode to screen

see "Screen" below

screen.png.abd1182e22d6457e5ddd35aaede542a0.png

skull.jpg.418bee198b6cb642dbe4a03a5e550cc7.jpg


Windows PCs. Photo and Designer, latest non-beta versions.

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2 minutes ago, toltec said:

I would invert the skull layer to make the skull black. Layer > Invert

skull1.jpg.01e61a82ba334c9d8e22d5bc710eb831.jpg

 

Put the green on top and change the Layer blend mode to screen

screen.png.abd1182e22d6457e5ddd35aaede542a0.png

skull.jpg.418bee198b6cb642dbe4a03a5e550cc7.jpg

Thank you - but that only solves part of my problem. I also need any pixels that are white in the example photo you attached to be transparent so that the green skull can be placed on a different colour background or over a photograph. Any thoughts on how that can be done? I'm so used to using Adobe Photoshop and it is fairly simple in that as I simply paste the greyscale image on to the layer mask (something that I don't seem to be able to do in Affinity Photo)

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Yes, sorry, I realised that just after posting.

 

Invert the skull layer to make the skull black. Layer > Invert

 

On the black skull layer, go Filter > Colours > Erase White Paper.

 

Nest the green layer (no need to use a blend mode, just drag it to the nesting position which is below and to the right of the thumbnail 

 

Nesting position

nesting.png.613ee8e11e22e9cd9fd13d2bf407347a.png

 

Nested

nest.png.2914655c5bb4eb654514e84c64b94374.png

 

skull3.png.b88fe8abd189a0a85275189a36e01497.png

 

Looks slightly messy because i only had a small screenshot. Your image should be fine.


Windows PCs. Photo and Designer, latest non-beta versions.

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I managed to find the solution that does both for me!

1) I selected the skull image

2) Clicked on Layer > Rasterise to Mask

3) dragged the new skull/mask layer underneath the green layer so it became the layer mask

4) placed a photo behine the skull

Now my skull is green and the white is transparant.

Thanks everyone for your suggestions.

ap-masks3.jpg

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Yes, that's a very good method too.

 

There are always plenty of ways to achieve the same thing in Photo. 

 

It's just a matter of finding them ;)


Windows PCs. Photo and Designer, latest non-beta versions.

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3 minutes ago, toltec said:

Yes, sorry, I realised that just after posting.

On the black skull layer, go Filter > Colours > Erase White Paper.

Nest the green layer (no need to use a blend mode, just drag it to the nesting position

which is below and to the right of the thumbnail 

Looks slightly messy because i only had a small screenshot. Your image should be fine.

Thanks toltec - your method appears to result in exactly the same thing as the 'convert layer to mask'. Thanks for sharing I had no idea that was a feature.

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1 hour ago, Alfred said:

Go to the Layers panel, right-click the skull layer and choose ‘Mask to Below’ from the context menu.

 

1 hour ago, Rob123456789 said:

Hi, thanks but I tried that and it doesn't acheive what I am after. Instead it results in a green square instead of a green skull (see attachment).

 

Sorry about that! As you've discovered, I should have said 'Rasterize to Mask' instead of 'Mask to Below' (and you need to nest the mask layer inside the green layer so that it doesn't mask out the background image).


Alfred online2long.gif
Affinity Designer/Photo/Publisher 1.7.3.481 • Windows 10 Home (4th gen Core i3 CPU)
Affinity Photo for iPad 1.8.2.174 • Designer for iPad 1.8.2.4 • iPadOS 13.3.1 (iPad Air 2)

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On 11/11/2017 at 2:56 PM, Rob123456789 said:

I managed to find the solution that does both for me!

1) I selected the skull image

2) Clicked on Layer > Rasterise to Mask

3) dragged the new skull/mask layer underneath the green layer so it became the layer mask

4) placed a photo behine the skull

Now my skull is green and the white is transparant.

Thanks everyone for your suggestions.

ap-masks3.jpg

This is exactly what I needed. This magical option "Layer > Rasterise to Mask" that I didn't know

 

 

 

 

 

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