Masks from B&W images

[MikeFromMesa]

I have been playing around with some luminosity masking tools and the way they worked made me a bit curious as to why much of this could not be done easily with B&W images. That is, I assume I should be able to take a color image, create a black and white image from it using the B&W layer adjustment, refine that to include what I want and convert that directly to a mask for the original image. That process works with Photoshop but I can not get it to work with Affinity Photo. I did some searching looking for phrases like "Affinity Photo convert B&W to mask" and other similar phrases, and found several links, but none of the instructions actually seemed to do what I wanted. One, on this forum, said I should create the B&W image, rasterize it to a mask and drag the layer to the original image layer until a vertical blue line appeared, but I could never get the vertical blue line and always ended up with the B&W image grouped with the original image, and never got a mask.

I am completely sure I am just doing this wrong. The tutorials talked about creating masks from selections, but I wanted to create the mask directly from a B&W image. Can anyone tell me how to do that?

Thanks.

 

[firstdefence]

To get the Black and white image to be a mask, put the Black and white image above the colour image, right click on the Black and white image and select Mask to Below

[MEB]

Hi MikeFromMesa,
To convert a black and white layer (or a colour layer) to a mask, select it then go to menu Layer ▸ Rasterise To Mask.

[MikeFromMesa]

1 minute ago, MEB said:

Hi MikeFromMesa,
To convert a black and white layer (or a colour layer) to a mask, select it then go to menu Layer ▸ Rasterise To Mask.

When I did the Google search for an answer to this question I found your response to the same question from 2015, and I tried it. It did not give me a mask. It only gave me a b&w image grouped with the original image, and nothing I could do actually gave me a mask.

I will do a screen video to show you what is happening and send it to you via a PM. I am sure I am doing something wrong, but I could not get your response to the old question to work.

 

[MikeFromMesa]

@MEB 

I have sent you a video of the steps that I took to try to create a mask from the B&W image via a PM.

 

[toltec]

32 minutes ago, MikeFromMesa said:

When I did the Google search for an answer to this question I found your response to the same question from 2015, and I tried it. It did not give me a mask. It only gave me a b&w image grouped with the original image, and nothing I could do actually gave me a mask.

I will do a screen video to show you what is happening and send it to you via a PM. I am sure I am doing something wrong, but I could not get your response to the old question to work.

 

Make a duplicate of the image you want to be a mask. Apply a black and white adjustment and adjust to suit, but click on Merge in the Adjustment panel.

Make sure the 'Mask' layer is selected in the Layers panel, then do as MEB suggests and go Layer > Rasterise to Mask.

P.S. Make sure it is not an Image layer (Placed).

 

[MikeFromMesa]

27 minutes ago, firstdefence said:

To get the Black and white image to be a mask, put the Black and white image above the colour image, right click on the Black and white image and select Mask to Below

Did that. It did not do what I expected, and I did not get a mask.

I am sure your instructions are correct, and that it works properly, but perhaps there is some intermediate step or setting that is wrong on my machine because it does not create a mask for me, but only creates a grouped image. The icon, which should show a mask, instead shows a B&W adjustment layer.

[MikeFromMesa]

5 minutes ago, toltec said:

Make a duplicate of the image you want to be a mask. Apply a black and white adjustment, and adjust to suit, but click on Merge in the Adjustment panel.

Make sure the 'Mask' layer is selected, then In the Layers panel, do as MEB suggests and click Rasterise to Mask.

P.S. Make sure it is not an Image layer (Placed).

 

OK. That worked. So there were multiple problems. I needed to duplicate the layer and I needed to Merge the B&W image.

Thank you for clearing that up.

[MEB]

1 hour ago, MikeFromMesa said:

@MEB 

I have sent you a video of the steps that I took to try to create a mask from the B&W image via a PM.

 

Hi Mike,
Please check your PM's.

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The Black and White Adjustment is only needed if you want to control how the colours of the image will be converted to greyscale. If you want to control the luminosity/greyscale values of the mask you can do so after the mask is created nesting a Curves or Levels adjustment to the mask (yes you can nest adjustments to masks too although not all work/are useful) and changing the channel dropdown on those adjustments to Alpha. This way you can keep these adjustments editable all the time.