Thin out dashes

[DynV]

ImageMagick version

6.9.12-98 Q16 x86_64 18038

Operating system, version and so on

Ubuntu 24

Description

I have an image made of manually drawn dashes what I need to thin out (made from an image editor paint brush). Is there a way to recognize the dash longest side and reduce the other side?

Thank you kindly

[fmw42]

Have you tried -morphology with as rectangular kernelSent from my iPhoneOn Mar 14, 2026, at 2:23 AM, DynV ***@***.***> wrote:- ImageMagick version 6.9.12-98 Q16 x86_64 18038 Operating system, version and so on Ubuntu 24 Description I have an image made of manually drawn dashes what I need to thin out (made from an image editor paint brush). Is there a way to recognize the dash longest side and reduce the other side? Thank you kindly —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[DynV]

I installed Imagemagick right before creating this thread and in the last 15 mins or so I tried the following (in quote) and none thinned it out visibly. I'd like to thin the dashes in the attached between 1/3 and 1/2 (in their smallest direction).

~/Pictures$ convert Thuoso-2-2X-dashes.png -morphology Thinning:-1 '3x1: 1,1,1' Thuoso-2-2X-dashes-Thinned.png
~/Pictures$ convert Thuoso-2-2X-dashes.png -morphology Thinning:-1 Skeleton Thuoso-2-2X-dashes-Skeleton.png
~/Pictures$ convert Thuoso-2-2X-dashes.png -morphology Thinning:1 Skeleton Thuoso-2-2X-dashes-Skeleton-2.png
~/Pictures$ convert Thuoso-2-2X-dashes.png -colorspace gray -negate -threshold 20% -morphology Thinning:1 "Skeleton" -negate Thuoso-2-2X-dashes-thinned_mask.png
~/Pictures$ convert Thuoso-2-2X-dashes.png -morphology Erode Disk:1.5 Thuoso-2-2X-dashes-reduced.png
~/Pictures$ convert Thuoso-2-2X-dashes.png -morphology Thinning:-1 Rectangle:1x3 Thuoso-2-2X-dashes-thinned.png
~/Pictures$ convert -version
Version: ImageMagick 6.9.12-98 Q16 x86_64 18038 https://legacy.imagemagick.org
Copyright: (C) 1999 ImageMagick Studio LLC
License: https://imagemagick.org/script/license.php
Features: Cipher DPC Modules OpenMP(4.5)
Delegates (built-in): bzlib djvu fftw fontconfig freetype heic jbig jng jp2 jpeg lcms lqr ltdl lzma openexr pangocairo png raw tiff webp wmf x xml zlib

Update 1: If it's needed to split the dashes per color or make them all grayscale (I'd prefer the former), that's fine.

[fmw42]

You could try -connected-components to get the end points of each object then redraw as desired Sent from my iPhone-On Mar 14, 2026, at 10:15 AM, DynV ***@***.***> wrote: I installed Imagemagick right before creating this thread and in the last 15 mins or so I tried the following (in quote) and none thinned it out visibly. I'd like to thin the dashes in the attached between 1/3 and 1/2 (in their smallest direction). Thuoso-2-2X-dashes.png (view on web) ~/Pictures$ convert Thuoso-2-2X-dashes.png -morphology Thinning:-1 '3x1: 1,1,1' Thuoso-2-2X-dashes-Thinned.png ~/Pictures$ convert Thuoso-2-2X-dashes.png -morphology Thinning:-1 Skeleton Thuoso-2-2X-dashes-Skeleton.png ~/Pictures$ convert Thuoso-2-2X-dashes.png -morphology Thinning:1 Skeleton Thuoso-2-2X-dashes-Skeleton-2.png ~/Pictures$ convert Thuoso-2-2X-dashes.png -colorspace gray -negate -threshold 20% -morphology Thinning:1 "Skeleton" -negate Thuoso-2-2X-dashes-thinned_mask.png ~/Pictures$ convert Thuoso-2-2X-dashes.png -morphology Erode Disk:1.5 Thuoso-2-2X-dashes-reduced.png ~/Pictures$ convert Thuoso-2-2X-dashes.png -morphology Thinning:-1 Rectangle:1x3 Thuoso-2-2X-dashes-thinned.png ~/Pictures$ convert -version Version: ImageMagick 6.9.12-98 Q16 x86_64 18038 https://legacy.imagemagick.org Copyright: (C) 1999 ImageMagick Studio LLC License: https://imagemagick.org/script/license.php Features: Cipher DPC Modules OpenMP(4.5) Delegates (built-in): bzlib djvu fftw fontconfig freetype heic jbig jng jp2 jpeg lcms lqr ltdl lzma openexr pangocairo png raw tiff webp wmf x xml zlib —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you commented.Message ID: ***@***.***>

[DynV]

Neither of the following give something that thins or making it easier to thin, the 2nd one unusable.

~/Pictures$ convert Thuoso-2-2X-dashes.png -colorspace gray -negate -threshold 20% -define connected-components:area-threshold=10 -define connected-components:mean-color=true -connected-components 8 -negate Thuoso-2-2X-dashes-connected-components.png
~/Pictures$ convert Thuoso-2-2X-dashes.png -colorspace Gray -contrast-stretch 0.5%x99.5% -median 3x3 -threshold 50% -define connected-components:area-threshold=30 -connected-components 8 -auto-level -morphology Thinning:-1 Rectangle:3x1 -morphology Thinning:-1 Rectangle:1x3 Thuoso-2-2X-dashesconnected-components-2.png