: Replicating fading/tearing effect in GIMP For a project we decided to use a freely available icon set that we could download. However it is now apparant that not all the icons that we need

@BetL875

An effect similar to the one in the examples given can be created with a variation of the Sketch-filter of the G'MIC plugin set for Gimp.



These are steps I took for re-creating this effect:


Choose a white background rather than transparent for the source
Select the monochrome icon with the select-by-color tool for effect inside of the icon contours only.
Apply the GMIC Sketch filter with the following settings:

Number of orientations 1
Starting angle 135
Angle range 180
Stroke length 130
Contour threshold 1.00
Opacity 0.15
Background intensity 0
Density 0.60
Sharpness 0.25
Anisotropy 0.05
Smoothness 0.75
Coherence 1.05
Untick Boost stroke
Untick Curved stroke
Color model White on black

Copy the resulting sketch to clipboard
Go back to the source image and undo the GMIC effect
Paste the clipboard in Screen mode.


Settings from the GMIC sketch plugin are quite versatile to fine tune the sketchy look to our taste. We could also let the strokes come from all angles, and more:

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@BetL875

I can't think of a way of doing the uneven line spacing other than creating a sophisticated brush and painting with it.

Given hatched lines, though, I was able, using GIMP to recreate the fading of the lines - final result can get like this - but it does require manual intervention:


(To get the even spaced lines - use the grid filter at filters->render->pattern->grid , and set line width to "0". Rotate the layer with the lines)

Afterwards, use the quick mask (click on the icon at the left of the horizontal scroll bar), and paint the region where you'd like the hatched lines to fade with white, using a soft brush and varying degrees of opacity - untoggle the quick mask, and you should have a selection suitable to the effect - the gray representation of the selection I used is this:


Then use the `Filters->Distort->Value Propagate" filter, set to propagate transparency. Downsize your image, and you should get the value above.

As I said, I can't think of a way short of painting or scripting to have the unevenly spaced, but parallel lines in GIMP. Scripting could also try to automate the steps of re-sizing the final image, tuning the hatch alpha, and creating the fade mask - effectively making the effect available for GIMP - but it would be a more sophisticated script than I can create for answering a question here, as it should take a some hours to get right.

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