Jump to content
You must now use your email address to sign in [click for more info] ×

Recommended Posts

Hi,

the "difference" blend mode is great to spot any differneces between 2 layers. Identical pixel blend to pure black, any difference are rendered to non-black, which can be amplified by a levels adjustment.

Unfortunately, this will only work when alpha is 1 (pure white). Otherwise, he blend formula will lead to non-zero results for color and below-one results for alpha, making this useless for spoting differences.

My question: Is this by design?

To be useful for spotting differneces, i would expect it to deliver RGB=0 and alpha=1 if both layers have equal RGB and alpha values, for those cases where alpha <> 1, too.

In the picture, you can find a gradient in the bottom from white to black, 100% opacity

In the top, a copy of the gradient with 50% opacity

On the left, the original gradients. On the right, i added a copy with blend mode "difference".

As you can see, only the right bottom quarter shows pure black as expected. The right upper quarter shows non-black, even if the layers are 100% identical both in RGB and alpha.

 

image.thumb.png.9eed89d66e93ee188fd9b7eb90c8a817.png

blend mode difference and alpha.afphoto

Mac mini M1 A2348 | Windows 10 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

 

Link to comment
Share on other sites

  • 3 weeks later...

Nobody interested?

Mac mini M1 A2348 | Windows 10 - AMD Ryzen 9 5900x - 32 GB RAM - Nvidia GTX 1080

LG34WK950U-W, calibrated to DCI-P3 with LG Calibration Studio / Spider 5

iPad Air Gen 5 (2022) A2589

Special interest into procedural texture filter, edit alpha channel, RGB/16 and RGB/32 color formats, stacking, finding root causes for misbehaving files, finding creative solutions for unsolvable tasks, finding bugs in Apps.

 

Link to comment
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...
×
×
  • Create New...

Important Information

Terms of Use | 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.