Episode 161: Playing with Wavelets

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The human skin isn’t as smooth and even as it used to be. At least if you are older than 12 or so. One way to keep up the illusion of eternal youth is image manipulation. Today I explore one way to smooth skin and keep it looking natural. That’s the problem with overly done make up and postprocessing – if you overdo it, faces look like made out of plastic.
There is a difference in size between “good” and “bad” skin structures. The Wavelet Decompose plugin can divide an image into “scales” and a “residual”. Each scale contains a part of the image with structures of a similar size. If you work on one of these scales, you are changing only these structures, not the smaller and larger ones. The plugin website does a better job of explaining this.

The show starts with a look back at Photivo and some comments I got in their Flickr group. “What’s wrong with some people?” – Well, some people haven’t read the Nettiquette…… šŸ˜‰

The TOC

00:20 Photivo revisited
01:25 GUI setup of Photivo
03:00 Right mouse button everywhere!
03:00 Detail curve depending on colour
05:20 Portrait “Make up”
06:40 Smoothing skin with Gaussian Blur
07:40 Masking out the eyes of the blur
08:20 Wavelet decompose
09:35 Plugin registry
11:35 Decomposing the image
13:20 A lot of ways to proceed
14:00 Painting with gray to hide details
14:40 Changing the opacity of some of the scales
15:15 Adding a layer mask
17:00 Looking at the scales in normal mode
17:25 Increasing contrast with a curve …
18:50 …sharpens the image
19:00 There is much more!

Creative Commons License
Meet the GIMP Video Podcast by Rolf Steinort and Philippe Demartin is licensed under a Creative Commons Attribution-Share Alike 3.0 Germany License.
Permissions beyond the scope of this license may be available at http://meetthegimp.org.

6 thoughts on “Episode 161: Playing with Wavelets

  1. About the Photivo gui: The widgets have a fixed aspect ratio and no limits on either size. I think this is a Qt4 issue solved in the newest versions.

    I had written about the wavelet decompose and sharpening plugins in the wiki, but I think there could be more. Right now my time is severely limited, but I’ll try to come up with something.
    Sadly, the plugins haven’t been updated for quite a while and there are some problems with the current development version and gegl activated. It’s not so easy to fix.

    @Rolf
    Nice portrait btw. I don’t think you’re a candidate for botox yet.

  2. Regarding the warning messages you received when you ran the plug-in, these messages appear because you are using the development version of GIMP and the messages are intended to instruct developers of potential problems that eventually need to be addressed. For the GIMP developers themselves, these problems should be fixed before the next stable release (2.8); however, plug-in developers should in most cases avoid updating their plug-ins until GIMP 2.6 is no longer in common usage* (else they need to maintain multiple versions of their plug-in and users need to ensure they install the appropriate version).

    These warnings are of no interest to users who do not participate in development and it would probably be best if such users disabled them by using the ”–pdb-compat-mode on” switch when invoking GIMP (typically changed by editing the preferences associated with a desktop icon).

    * In some few cases, the third-party plug-in developers may wish to provide an updated version which exploits new features that have been added to GIMP (for example, it might be good to have all of the layers generated by Wavelet Decompose collected together as a layer group). But if the plug-in is not using new features then it is best to continue to use the deprecated function names (when GIMP 2.8 is eventually released, the warnings you currently see will be disabled).

  3. I think, for the show the warnings should be left on for the moment. Because this way it’s always clear a development version is used and plugin creators won’t have to worry about their plugins doing strange stuff on the stable 2.6 version.

  4. I really like this kind of mathegraphical or photomatical stuff! Thank you for the show. I think this plugin offers endless options. Could anybody give some suggestions for optimal denoising settings (number of layers and position of layer to remove or modify)? I think wavelet decomposing must be a very suitable tool for denoising, however, my results are not as convincing as those achieved applying other tools. Sharpening seems to be easier. Just doubling the third layer (as needed even twice or triply) enhanced sharpness with barely pushing halos or noise in many cases. Very simple, fast and effective. I’ll have to do further experiments. And I would be very happy about a sequel of the show …

  5. @Bert
    There are two other wavelet based plugins, which might suit your need better: Wavelet Denoise and Wavelet Sharpen. As far as I understand it, they use different frequency separations from the decompose plugin, so you’ll get different results.
    It’s also possible some of these algorithms will find their way into other programs like Photivo or Darktable and take advantage of the availability of raw data.

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