Channel Selection

[cwill2124]

I am trying to do a channel selection for hair. How i use to do it in PS was I would create a new channel by using calculate. Then I would apply a levels adjustment on the channel to up the blacks and whites. Then using a paint brush set to overlay, I would paint out the grays to either black or white. Make my selection turn off the channel and turn on the other and good to go. In Affinity photo, I cannot figure out how to calculate to channels together, which is fine, I can use one. But I cannot create a new channel or paint on a channel. How can this program be so good and bad at the same time. This is something you need in a pro workflow. I don't know anyone who uses selection tools on most of their work. I was taught and have only seen pen tool and channels. Why cannot I not do this? Or am i just overlooking something. I have spend to long trying to figure this out and there seems to be no youtube videos on it.

[NotMyFault]

Hi cwill,

 

i just uploaded a tutorial for a similar question. I did not fully understand your PS workflow, if you can provide a hint i migth find a similar solution for Affinity.

 

regards,

Timo

 

[Affinity Rat]

I too would like to use channels to make selections of hair on dark backgrounds.

The goal is to create contrast to make the selection.

My procedure in PS was:

• Look at the RGB channels to determine which has the most contrast.
• use levels or curves to create more contrast in the most contrasting channel layer 
• after increasing contrast in that channel, duplicate it
• use curves to increase the midtones
• use the newly created channel and apply it to itself with “Screen” blending option thus amplifying the contrast (using apply image command)
• In Levels drag left shadow slider to right to darken the edges, and move Highlite slider to left to lighten background
• using a brush paint in black (alpha channel) those areas you obviously want to select (appears grey scale)
• Use brush in “soft light” blend mode to touch up edges
• use pen tool to accurately select none hair areas to be selected
•  Invert the alpha channel
• use levels again to make background black, moving left slider to right
• load alpha channel as selection
• finished with curves adjustment so delete it
• Using the mask created from alpha channel copy the composite color to a new layer

Piece of cake!