Legacy ImageMagick Discussions Archive

Hi, I've been searching for a program that can do resize, filtering and unsharp mask in a batch. Sound simple eh? However none of the programs that i found so far can do everything right. Photoshop has a nice filters, but lacks high quality resizing. Other programs like ifranview have a nice resize (lanczos) but missing filter options. Yet other programs lack a batch process feature.
Right, now i'm doing filtering in photoshop and resizing in ifranview, which is not convinient at all, because i have to do stuff manually and intermediate files need to be saved/read.

I haven't played with ImageMagick yet, but i believe ImageMagick has high quality resize and batch features.
However I'm not sure about the filtering. I'm looking for a very similar filter as the Reduce Noise filter in Photoshop.
I'm not sure what this filter does exactly under the hood, but i really like it. The settings i use for this filter in Photoshop are:
- Strength 10
- Preserve detail 8
Other options are set to 0 or disabled.

In the end i want to batch process lots of huge pictures to smaller thumbs suitable for the web. What i would like the batch to do is the following:
- resize to 320*240 (i would like fairly large and detailed thumbs)
- apply noise filter
- do a subtle unsharp mask
- save to png and jpg

Other features that would like (but not a must) are: median filter and (auto) levels.

Another question i have is: Why are there differences in lanczos resizing? For example Irfanview looks quite different than Faststone. I prefer Irfanview because faststone gives ringing.

You can do all that in ImageMagick, including median and auto levels. I don't know how IM's noise reduction compares to Photoshop's -- I don't use PS, nor do I de-noise images.

You would have to play with IM to see what you like. For example:
You can specify the resize filter, if you want. I use the defaults, and have never experienced ringing.

Alright, thanks, i will check it out as soon as i'm home. Your command line will give me a good start.

It's just an example, of course. The numbers I gave may give horrible results. Try out one option at a time, with different (probably smaller) numbers.

You may also want to check out my isonoise and statsfilt noise filters which are unix bash scripts. see link below

So far so good. The resize and unsharp work perfectly. I've tried all different resize methods and i prefer Box for my needs. It is sharpest without ringing. The unsharp settings are exactly the same as in PS. I also played with the jpeg settings. This is what i used:
Try it, it looks awesome! imho :p. Maybe the file is a bit big for a thumb, but i don't care.

I haven't tried noise filtering yet, which will probably be a little harder to do. Fmw42, i will try your script when i have some more time to figure them out.

Thanks!

see also IM -despeckle

And -blur and -adaptive-blur. It depends on the nature of the noise, of course.

W00t, turns out that "-enhance" does almost exactly what i was looking for in a noise filter. Too bad it doesn't have any tweak option though. I would like to tone down the filtering effect a tiny bit. Oh well, i'm very happy with the current result nevertheless.

try -despeckle, it may be a tad better than -enhance

I tried despeckle but it does not give the result i'm looking for, it removes details that i want to keep. Enhance is close to PS, it blurs colors that are almost the same. However the effect is way to heavy.

You can lessen the effect of enhance (or other filter) by making it transparent and overlaying on the original. Vary the multplier between 0 (zero effect) to 1 (full effect).

Yes, that might be a good idea. Another idea i had is to apply the filter before resizing.

Well, it's almost weekend so more time to mess around .