Legacy ImageMagick Discussions Archive

I think clamping after the blur makes no difference. The important part is that (O-GB) may be negative, so that mustn't be clamped. "-compose Mathematics" works pixel-by-pixel, with each calculation in floating point, though each result here is then written to Q16 integer. My guess is that...

Snibgo, in your -compose mathematics, you are processing O + (O - GB) as 2*O-GB with no clamping. Strange that works. But the claim was that PS is using O+(O-GB)-inv(O+inv(GB)). My guess is that the third term is getting parts missed by clamping O-GB. Nevertheless, when I computed O+(O-GB) in my scr...

We can avoid the need for HDRI by using "-compose Mathematics":

If we want the long-winded form of "-unsharp", then: set SRC=lena3.png %IM%convert %SRC% -unsharp 0x3+1+0 u0.png rem out = O + (O-GB) %IMDEV%convert ^ -define compose:clamp=off ^ %SRC% ^ ( -clone 0 -gaussian-blur 0x3 -clamp ) ^ ( -clone 0-1 -compose MinusSrc -composite ) ^ -delete 1 ^ -com...

Yes, I have the order correct for subtraction. If you do multiple composites, each gets its own clamping. That is why I though of doing the 3 adds in one operation and not two. My guess is that there is different clamping in IM as separate operations than is what is done in the -unsharp command. Or ...

Yes, I forgot about the default .05 threshold when I originally posted, but have changed the post to set the threshold to 0 exactly. See my previous post and http://www.imagemagick.org/script/command-line-options.php#unsharp. So my compare rmse value is now even smaller. Good stuff! That's great ne...

Yes, I forgot about the default .05 threshold when I originally posted, but have changed the post to set the threshold to 0 exactly. See my previous post and http://www.imagemagick.org/script/comma ... hp#unsharp. So my compare rmse value is now even smaller.

... noise is less in smooth areas. But I still don't understand why the fully manual version does not work with IM. I put a video here how I do it in Photoshop. I'm no video producer, so it will be a little slow and clunky..but you should get the idea: https://www.youtube.com/watch?v=8Yae5V39EhQ

Here is another way to do O+(O-GB)-inv(O+inv(GB)) im6937hdri convert lena3.png \ \( -clone 0 -gaussian-blur 0x3 \) \ \( -clone 0 -clone 1 +swap -compose minus -composite \) \ \( -clone 1 -negate -clone 0 -compose plus -composite -negate \) \ -delete 1 \ -evaluate-sequence add \ lena3_im_us_script3_3...

snibgo wrote:Does the PS "amount" allow values above 100, like (say) 500 or 1000?

If an effect is exaggerated, it is easier to find what causes the effect, and how to replicate it.

PS unsharp masking does allow amounts up to 500%.

The PS apply image seems to be limited to 0 to 100%

Does the PS "amount" allow values above 100, like (say) 500 or 1000?

If an effect is exaggerated, it is easier to find what causes the effect, and how to replicate it.

I didn't test it with Scale 2 yet. The only steps I did where the steps for "O+(O-GB)-inv(O+inv(GB))" this replicates PS USM 100, 3, 0, and closest match for IM was your "-unsharp 0x3" example in that case.

If you like I can make a video showing how I do it if that would help?

When you have time, list for me the exact operations you used in PS with the argument values to reproduce what you found matched the IM results and which IM result that I made above.

Where is this scale in the PS unsharp masking? I only see amount, radius and threshold. It's in the PS menu "Image/Apply Image...", then select Subtract or Add and you will see Scale and Offset as additional options. You use Apply Image to do the addition and subtraction operations of the...

Where is this scale in the PS unsharp masking? I only see amount, radius and threshold.