Copy link to clipboard
Copied
Parameters of "Apply Image" : blending operation/scale/offest are never explained in tutorials on Frequency Separation
I understand that for image 8bits (luminance R/V/B coded from 0 to 255), to get high frequencies (structure) we substract low pass image from original, then the result values are from -255 to + 255, so we use a scale of 2 to reduce values to -128 to +127 and then an offset of 128 to get a final 8bits value from 0 to 255.
For 16bits images (luminance R/V/B coded from 0 to 65535) all tutos use without explanation : Addition with inversion of low pass layer, scale 2 , offset 0. I don't understand how it works ?
Furthermore using substract without inversion seems to give the same result (seems to me normal since addition of the inverse is equivalent to a substract), so what is the reason of this choice ?
Copy link to clipboard
Copied
You've posted this in Using The Community.
Please let us know which Adobe tool you're using, and a moderator will move your post to the relevant community.
Copy link to clipboard
Copied
I use Photoshop 22.2.0 for frequency separation method with "Image/Applys Image..."
Copy link to clipboard
Copied
For 16 bpc, one should introduce a 128 offset with subtract, which leads to a lossy conversion (for what that may matter).
The "standard" 16 bpc method produces a lossless conversion, depending on why one is using frequency separation, this may or may not have a critical affect.
Let me dig up a link for you...
EDIT: There are 26 pages in the topic thread, here is page 1 –
https://www.modelmayhem.com/forums/post/439098
Here is my action:
https://www.dropbox.com/s/7sf1xcijtzdygyh/Frequency%20Splitter%20v4%20Conditional.zip?dl=0