Relief Light for selective illumination

[s7habo (Boris Hajdukovic)]

I have just discovered a very interesting application of Relief Light Filter to enhance the selective illumination of the scene. Here are a few examples:

The cool thing is, the illumination is not linear but follows brighter and darker areas of the image and creates “relief light” as you can see in the example below. The example also shows the problem - shadows on the trees should be reversed:

A few questions to @David_Tschumperle and GMI’C people about possible improvements and extensions of the filter. Would it be possible to:

1. invert Relief (Z-scale): The shadows should be reversed
2. add multiple specular lightness points
3. change shape of speculer lightness
4. change color of specular and ambience lightness
5. to save only lightness to new layer (e.g. to be able to experiment with blend modes later)

Anyway, filter opens up a lot of possibilities for me to improve photos and I’m still experimenting.

[s7habo (Boris Hajdukovic)]

I’m still experimenting and haven’t been able to get the illumination alone, but I discovered an interesting effect by removing the color black from this layer in the GIMP and combining it with the original layer:

1. Apply the effect to a duplicate of the original layer

2. Add alpha channel to this layer and remove black color using “color to alpha” (from colors menu):

3. Choose soft light blend mode for this layer (reduce opacity if effect becomes too strong):

Before and after:

[afre (Alan)]

Would this work for you? Made a quick one-liner command.

[paperdigits (Mica)]

@afre what is the one liner??

[afre (Alan)]

I ran out of time but I will make a filter. I promise.

[afre (Alan)]

Made a PR, waiting to be committed. It is minimalist and a bit whimsical; i.e., different combinations of parameters do different things visually. It might not be what @s7habo is looking for but as a filter it may be useful enough to exist.

---

Original

Gleam

Shroud (negated Gleam – will add later)

[s7habo (Boris Hajdukovic)]

First of all, thanks a lot, @afre ! I am curious to see what your Gleam Filter does!

As long as I don’t have it, I’ll try to explain it in more detail, what I find interesting, if this would be possible:

What I find very elegant when editing photos is to try to direct the eye of the viewer to the subject by soft illumination of certain areas.

This can be done by intensifying the already existing illumination or by “artificially” illuminating it (which you could achieve, for example, when photographing with flash and softbox).

Digitally, one can try to imitate this with the help of Dodge and Burn technique. Depending on the subject, this can be very tedious. You have to make sure that the light is distributed in such a way that it looks realistic.

Let’s illustrate this with an example:

In this picture the forest is well lit. And we have hiker who enjoy this view but it is in the shadows. I would like to bring the area with her a little bit more into focus by soft illumination.

I can do this in the GIMP by painting the areas on a new transparent layer with the white brush and then…

…use soft light blend mode to illuminate the lower layer:

Well, what I liked about the Relief Light Filter by @David_Tschumperle , the illumination takes into account to some extent the distribution of light in light and shadow areas (here the example is exaggerated to make it clear):

Now, if I de-saturate this layer and remove black, I have a layer to lighten the area:

With soft light blend mode, I get a nicely illuminated area that looks natural:

If I also apply the Gaussian blur to this layer, I get even smoother transitions of light and shadow:

[afre (Alan)]

@s7habo

First of all, thanks a lot, @afre ! I am curious to see what your Gleam Filter does!

As long as I don’t have it, I’ll try to explain it in more detail, what I find interesting, if this would be possible:

Thanks for your fuller explanation! Gleam is meant to be as minimalist as possible, but it might be extended to do what you describe, eventually. Don’t have the time or sanity at the moment.   afre_gleam isn’t available yet, at least for me, when I do gmic up or click the Update button, even though the PR has been accepted. I don’t understand why I have to wait several days every time I change something…

PS I fixed your typo and shortened the thread title.

[KaRo (Karsten R)]

You can see from which date and time the generated updatexxx.gmic file stems by

head .config/gmic/update281.gmic on unix and Mac

under Windows seemingly a bit more complicated

powershell -command "& {get-content C:\Users\xxxx\AppData\Roaming\gmic\update281.gmic|select-object -first 15}

#@gmic

File : update281.gmic

( G’MIC command file )

Description : Update file for G’MIC commands and filters (for current version 2.8.1).

( https://gmic.eu )

License : CeCILL v2.1

( https://cecill.info/licences/Licence_CeCILL_V2.1-en.html )

Generated on : 2019/12/20, 15:14

Possibly the background job hangs occasionally.

[afre (Alan)]

I get the same timestamp, which is 3 days ago; so it isn’t just me…

>type C:\Users\afre\AppData\Roaming\gmic\update281.gmic | find "ted on : 20"
#  Generated on : 2019/12/20, 15:14

[nrcarla]

Nice illustration.

@afre

It is minimalist and a bit whimsical

Great filter.

[afre (Alan)]

Wrote another quick one-liner. Isn’t perfect but does this work for you?

Hiker in

Hiker out

[s7habo (Boris Hajdukovic)]

Thanks @afre but this version is a little bit pale
The contrasts are gone as if illuminated with a 20-meter softbox

[s7habo (Boris Hajdukovic)]

By the way, your Gleam Filter is interesting. It is very similar to the bloom filter in darktable:

This has potential. If you could also control the direction of the illumination so that it doesn’t evenly illuminate all bright areas of the image…

[afre (Alan)]

@s7habo

but this version is a little bit pale

I have been pretty pale myself lately. Funny you used . Several people used to call me that because they couldn’t pronounce my name.

@s7habo

The contrasts are gone as if illuminated with a 20-meter softbox

I went overboard with that one, didn’t I.   Just trying different things.

@s7habo

bloom filter

Is that good or bad? I have never used or examined a bloom filter before. I generally go my own way and code and process as I see fit.

@s7habo

This has potential.

Thanks! You are gleaming with realized potential. I appreciate your ideas.

[s7habo (Boris Hajdukovic)]

@afre

Just trying different things.

Yes, please, keep playing.

@afre

Is that good or bad?

Is good. That bloom glow with multiply blend mode and a little brightening gives the image beautiful soft illumination: