Help, how did I get this backlight effect?

[dmerces]

Hello my fellows,
I don't know if this is the right place to ask this kind of question. If it isn't, I apologize, but I'm feeling extremely stupid and I really need your help: I produced an image about 30 days ago and now I can't repeat the steps to get the same effect. Both images, the source image (DM Logo Work) and the final result (DM Logo - Edge_3), are attached.
 
The only clue I have is that I used neon and sobel edge detection types, and maybe color curve, color equalization and color desaturation on the attached logo. Unfortunately, I can't remember anything else. My initial intention was to get a Sketch effect, but I ended up accidentally getting this effect, which I really liked, but unfortunately I don't know how to reproduce it. Five days today trying various alternatives with no success.
 
I'm sorry to bother you with this stupid question, but at 70 years old my reasoning ability is decreasing and my anxiety is increasing tremendously. Be patient with me, please.

Thank you in advance for your help.

DMerces

[sallyanne]

(08-21-2024, 01:14 PM)dmerces Wrote: Hello my fellows,
I don't know if this is the right place to ask this kind of question. If it isn't, I apologize, but I'm feeling extremely stupid and I really need your help: I produced an image about 30 days ago and now I can't repeat the steps to get the same effect. Both images, the source image (DM Logo Work) and the final result (DM Logo - Edge_3), are attached.
 
The only clue I have is that I used neon and sobel edge detection types, and maybe color curve, color equalization and color desaturation on the attached logo. Unfortunately, I can't remember anything else. My initial intention was to get a Sketch effect, but I ended up accidentally getting this effect, which I really liked, but unfortunately I don't know how to reproduce it. Five days today trying various alternatives with no success.
 
I'm sorry to bother you with this stupid question, but at 70 years old my reasoning ability is decreasing and my anxiety is increasing tremendously. Be patient with me, please.

Thank you in advance for your help.

DMerces

I cannot get the white lines all the way around but...did you try softglow? that will give the white edges a glow.

Also if this is not your answer - did you use just gimp or the plugin GMIC-qt as well?

[denzjos]

That's how I did it : select the blue and grey with the 'Fuzzy Select Tool'. Then 'Select / To Path' and 'Select / None'. Make a new black layer, a transparent layer and a copy layer from the original picture. On the transparent layer stroke the path with white Paintbrush (Hardness 12, Force 14, Size 170). Make the original layer copy black : Colours / Desaturate / Mono Mixer (green slider to the left

   

[rich2005]

@dmerces   The source image DM Logo Work was made with Inkscape so you might have an svg (with paths) somewhere.  You also posted on GimpChat with a png (with transparency) version of DM Logo edge, which is a better target than the jpeg version.

I can get there quite easily, if a little tedious by stroking and blurring paths. No svg so you have to make the paths. Also two colours so two iterations of the same procedure.

Make transparent layers for each colour. Working on one of the layers.

1. Paths
Use color select and enable sample merged. Select by colour. Select -> To Path. Kill the selection Select -> None

2. Stroke the path with the FG colour size about 20 or 30 pix. Gaussian Blur the layer, for this one about size (x,y) about 20.

3. Delete the shape. Select -> Path to Selection then Edit -> Cut  Select -> None.


Move to the other empty layer and repeat with the other foreground colour.

This a 50 second animation of that so do not blink. https://i.imgur.com/YiZCw5a.mp4  (chopped second iteration to fit into 60 seconds for imgur)

For a single layer, merge the two outline layers. Layer -> Merge Down.

Edit: That animation ends rather abruptly This the transparent layer (with black BG) and the colours are about 50% alpha much the same as the DM Logo - Edge_2.png

   

[dmerces]

SallyAnne, Dzenjo and Rich 2005, thanks to you three I’m finally able to reproduce my steps to obtain the effect I posted and I did no longer remember how I’ve got there. My method does not have the sophistication and technique of the methods all of you suggested. The steps I followed to obtain my effect were completely accidental. It was my birthday and I already had the "inspiration" coming from a few shots of Jack Daniel's.

Thanks your ideas I could reproduce my past steps and even improve the first version of my effect. Here are the steps I followed for the first version and for the improved version, so called because it implements a single color as backlight.

Thank you very much for your time and support and for so many inspirations and lessons with your techniques. Tonight I will sleep really relieved.

Original Effect Version
Steps
1. Set background color to white.
2. Remove Alpha Channel
3. Difference of Gaussians: Edge-detect> Difference of Gaussians | Radius 1=1,000; Radius 2=20,000
4. Color to Alpha: Color>Color to Alpha | Set target color to black.
5. Add any dark background layer and save the image.

Improved Version
Steps:
1. Open the image DM Logo Work.png
2. Set background color to white
3. Equalize: Color> Auto> Equalize
4. Mono Mixer: Color>Desaturate>Mono Mixer | Green =5,000
5. Difference of Gaussians: Edge-detect> Difference of Gaussians | Radius 1=1,000; Radius 2=20,000
6. Color to Alpha: Color>Color to Alpha | Set target color to black.
7. Add any dark background layer and save the image.

[rich2005]

Well, really pleased you regained your memory. I have the same problem with house keys.

However, the image you posted on gimpchat.com DM Logo - Edge_2.png did have two colours.

   

How did you do that one ? Edit: OK, you do get that using Edge detect -> Difference of Gaussians