Here is the result of the first experiment:
Attachment:
smoothEyeExp1.jpg [ 2.95 KiB | Viewed 4703 times ]
Here is the result of the second experiment:
Attachment:
smoothEyeExp2.jpg [ 2.74 KiB | Viewed 4703 times ]
The difference between the two experiments was the method of edge detection (as implemented in Gimp).
- First experiment (Sobel): strokes the edges astride the edge locations
- Second experiment (Difference of Gaussians): strokes the edges onto the darker side of the edge locations
Stroking the edges astride enlarges dark zones of the image. This effect distorts the eyes of persons.
So, for "Comic Book" effect, I prefer stroking the edges onto the darker side.
Here are some Gimp (and G'MIC) filters that stroke astride:
- Filters -> Edge-Detect -> Edge... (all the algorithms except Laplace),
- Filters -> Edge-Detect -> Neon...
- Filters -> Edge-Detect -> Sobel...
- Filters -> Edge-Detect -> Image Gradient...
- Filters -> G'MIC-Qt... -> Contours -> Edges
- Filters -> G'MIC-Qt... -> Contours -> Edge
- Filters -> G'MIC-Qt... -> Artistic -> Cartoon
- Filters -> G'MIC-Qt... -> Artistic -> Poster Edges
- Filters -> G'MIC-Qt... -> Testing -> Jayprich -> Jpr Line Edges
- Filters -> G'MIC-Qt... -> Testing -> Joan Rake -> Artistic -> Neon
- Filters -> G'MIC-Qt... -> Testing -> Joan Rake -> Contours -> Gradient Norm [JR's mod]
- Filters -> G'MIC-Qt... -> Testing -> Naggobot -> Smooth Sketch
- Filters -> G'MIC-Qt... -> Testing -> PhotoComix -> Color Sketch
Here are some methods that stroke onto the darker side:
- Filters -> Edge-Detect -> Edge... (Laplace),
- Filters -> Edge-Detect -> Laplace...,
- Filters -> Edge-Detect -> Difference of Gaussians... (radius1 greater than radius2),
- Filters -> Edge-Detect -> Difference of Gaussians (legacy)... (radius1 greater than radius2),
-
- Duplicate layer
- On bottom layer, "Filters -> Blur -> Gaussian Blur..."
- On top layer, set "layer mode" to "subtract"
- On top layer, "Merge down"
- Filters -> Artistic -> Cartoon...
- Filters -> G'MIC-Qt... -> Contours -> Morphological Filter (Action = Dilation - Original, size=2)
- Filters -> G'MIC-Qt... -> Artistic -> Comic Book
- Colors -> Tone Mapping -> Retinex... (Low, 16, 3, 0.1)
(Exception: For more artistical results, some little distortions can be needed. So, I think, in this case, it's better not to follow this tutorial!)
The tutorial is finished.