Jump to content
Sign in to follow this  
dmstraker

AP: Saturation mask (experimental)

Recommended Posts

I've been puzzling over how to create a saturation mask, where the darkness/lightness mask represents the saturation of the colours. You can select by hue and luminosity, but not by saturation level, which is a shame as it is possible in PS. Here's what I did, with images.

Note: All adjustment layers are above the image, with the whole set collected in a group.

Initial image has overlaid strips of RGBKMYC, fading from white and to black. They are at greatest saturation in the middle, so we should see this being selected.

akit1.thumb.png.330d286456aa761567ec6f79166fcbec.png

First step is to add an HSL layer, dragging Saturation to zero. Then set Blend Mode to Subtract.

akit2.thumb.png.038ba465f503733cbce60b6a8245d169.png

Here we can see the central areas of the strips are coming through, which is what we want (I tried Difference blend but it wasn't the same).

There's more detail in there, but we can't see it at the moment, so add an Invert layer.

akit3.thumb.png.e0b80c25a2f1e940506116ee188074c3.png

To make it black and white for masking, add a Black/White layer.

akit4.thumb.png.a996cd6f2714f003da049dcbe8c26d62.png

This is all rather faded, so add a Levels layer and drag the Black up to meet the histogram and improve contrast.

akit5.thumb.png.91934a44d3c492c3d9fe2a243e8f061b.png

We can now create a mask from this. Invert it again if you like to select the more saturated colours.

Here's a quick example, with the mask loaded to a Curves layer which has been pulled up to affect lower saturation areas (note the lighter and darker areas of the strips are lifted) but higher sauration is not (as can be see in reds such as the draining board stand).

akit6.thumb.png.54cdd121d96c874daaf9164ca660425a.png

As this effectively converts saturation to luminosity, areas of it can be selected with Blend Ranges, for example just the most or least saturated.

The principle could also be applied to any other adjustment, subtracting it from the original and turning this into a mask.

Bottom line - does this make sense? Have I fallen over any tripwires?


Dave Straker

Cameras: Sony A7R2, RX100V

Computers: Win10: Chillblast i9 Custom + Philips 40in 4K & Benq 23in; Surface Pro 4 i5; iPad Pro 11"

Favourite word: Aha. For me and for others.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...

Important Information

Please note the Annual Company Closure section in the Terms of Use. These are the Terms of Use you will be asked to agree to if you join the forum. | Privacy Policy | Guidelines | We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.