Search found 12 matches

by Drazick
2015-08-08T12:04:35-07:00
Forum: Digital Image Processing
Topic: Image inpainting
Replies: 6
Views: 12601

Re: Image inpainting

I think there are new modules in OpenCV for that.
by Drazick
2015-08-08T11:59:47-07:00
Forum: Digital Image Processing
Topic: Audio equalizer for images?
Replies: 14
Views: 39072

Re: Audio equalizer for images?

What about doing it using Wavelets / Image Pyramid?
by Drazick
2014-11-16T23:58:19-07:00
Forum: Digital Image Processing
Topic: The Math Behind Photoshop's Unsharp Mask and Gaussian Blur
Replies: 50
Views: 68234

Re: The Math Behind Photoshop's Unsharp Mask and Gaussian Blur

You corrected your answer after I wrote that the magic happens due to clipping in each step.

Yet clipping, since it is Non Linear, must be done at each iteration and not like you wrote.

Try it by yourself.
by Drazick
2014-07-28T01:13:56-07:00
Forum: Digital Image Processing
Topic: The Math Behind Photoshop's Unsharp Mask and Gaussian Blur
Replies: 50
Views: 68234

Re: The Math Behind Photoshop's Unsharp Mask and Gaussian Bl

It turns out the magic happens when after each addition / subtraction operation you clip the image into its range.
by Drazick
2014-04-28T05:29:49-07:00
Forum: Digital Image Processing
Topic: The Math Behind Photoshop's Unsharp Mask and Gaussian Blur
Replies: 50
Views: 68234

Re: The Math Behind Photoshop's Unsharp Mask and Gaussian Bl

Thank You for the simulations.

Yet again, what's interesting here is why Photoshop does it and why the direct calculation is different from the "Long Calculation"?
by Drazick
2014-04-27T21:56:43-07:00
Forum: Digital Image Processing
Topic: The Math Behind Photoshop's Unsharp Mask and Gaussian Blur
Replies: 50
Views: 68234

Re: The Math Behind Photoshop's Unsharp Mask and Gaussian Bl

Let's try it again. Can wee agree that inv(L) = White - L? USM(O) = O + (O - B) - inv(O + inv(B)) = 2O - B - (White - (O + (White - B))) = 2O - B - (White - (O + White - B)) = 2O - B - (White - O - White + B) = 2O - B - White + O + White - B = 3O - 2B. So I was right whether it is a [0, 1] image or ...
by Drazick
2014-04-27T15:27:33-07:00
Forum: Users
Topic: How does -unsharp work?
Replies: 17
Views: 17748

Re: How does -unsharp work?

I think the documentation isn't updated since I clearly see that GIMP is close to Photoshop.

I promise you Photoshop does what I wrote above.

I just don't know why.
by Drazick
2014-04-27T15:12:24-07:00
Forum: Users
Topic: How does -unsharp work?
Replies: 17
Views: 17748

Re: How does -unsharp work?

Leave the threshold aside for the aske of this dicussion. Open Photoshop and try: USM(O) = O + (O - GB) - Which is as you set Amount to 100. You'll see it is not replicates Photoshop's USM. Then try the method I suggested: USM(O) = O + (O - GB) - inv(O - inv(GB)) And you'll see it's 100%. The first ...
by Drazick
2014-04-27T14:30:52-07:00
Forum: Users
Topic: How does -unsharp work?
Replies: 17
Views: 17748

Re: How does -unsharp work?

There's a big difference.
Photoshop does something like "Dark Halos" + "Light Halos".

See what I linked.

I think Image Magick does USM(O) = O + Amount * (O - GB)
Photoshop is different.
by Drazick
2014-04-27T13:24:46-07:00
Forum: Users
Topic: How does -unsharp work?
Replies: 17
Views: 17748

Re: How does -unsharp work?

I think Photoshop works a bit different which produces much better results:

viewtopic.php?f=22&t=25477
by Drazick
2014-04-27T13:18:32-07:00
Forum: Users
Topic: IM Unsharp vs PS USM
Replies: 3
Views: 7028

Re: IM Unsharp vs PS USM

I think Photoshop's Unsharp Mask is completely different from IM and GIMP.
Look here:

viewtopic.php?f=22&t=25477
by Drazick
2014-04-27T10:39:06-07:00
Forum: Digital Image Processing
Topic: The Math Behind Photoshop's Unsharp Mask and Gaussian Blur
Replies: 50
Views: 68234

The Math Behind Photoshop's Unsharp Mask and Gaussian Blur

Hello, Has anyone succeeded replicating Photoshop's Gaussian Blur and Unsharp Mask? When I say replicating, I mean up to a rounding error or something like that. It looks like Photoshop is doing something beyond the classic and I want to know what exactly to be able to reproduce things I do in Photo...