Legacy ImageMagick Discussions Archive

I was wondering if Focus Stacking is possible with IM ?

I'm aware of all the free/commercial products like CombineZ, but I'm looking for something I can script myself, and to avoid including too much third party stuff in my application.

I'm on Win7 32bit so cant use Hadley's IM/CombineZ combo as it requires 64bit Windows, I've also been looking at Enfuse/EnBlend, but again, would be awesome if something similar could be done with IM.

If the Hugin tools can do it, that's probably the best solution. Those tools are awesome interactively, and nearly awesome in batch.

IM has lower-level tools, so scripts would have to be built. If the images are aligned, I guess these would be fairly simple, using masks that identify which images have the best focus, along the lines of http://im.snibgo.com/zingph.htm#lbdm

I am using CombineZP under Win 7 32 bit without problems, so there still must be 32 bit versions around.

I cannot see how the trick could be performed with IM, even by use of a complex script. You would have to identify the (non-rectangular) regions in which some photo has the sharpest focus and then mount all these regions, found in various photos, into a new version of the entire photo.

Even in a dedicated program, this seems to be a tricky job, as most programs don't do a convincing job on that, with CombineZP being one of the exeptions!

I don't think it would be difficult with IM. Yes, I know the proof is in the pudding and I haven't cooked it yet, but it's on my list.

My thoughts are: start with two images of the same size.[*] Can we decide, for each coordinate, which image is sharper? Yes. There are various measures, such as the standard deviation of an n*n square around the pixel. This easily gives us an image that is black where image #1 is best, or white where image #2 is best. Use that black/white image as a mask for "-compose Over" of image #1 and image #2.

The concept is easily extended to an arbitrary number of input images. In theory.

[*]Yes, we already have a complication. When a camera focuses, the lens moves in and out, changing the angle of view so images at different focuses need resizing. That's probably the harder problem to crack. A trial-and-error approach might work well.

I don't think that CombineZP scales the photos before mounting them together. They are just aligned in the first step.

Ideas for coding can possibly be taken from Fiji/ImageJ, which also provides a Java module for focus stacking and is Open Source.

Your basic idea – to calculate the sharpness in the neighbourhood of each pixel an then just take the pixel with the highest value - sounds convincing. Could possibly be performed with fx:, which however lacks a genuine max operator, working on an array (and not just two values).

My theories often sound convincing until they fall apart. Nevertheless, the camera is charged up, and I'm just waiting for a bit of sun on a handy brick wall.

I avoid fx for 35 Mpix images. Life is too short. "-compose MinusSrc -composite -fill White +opaque Black" is a useful "less than" operation.