Legacy ImageMagick Discussions Archive

Hello!

$ magick --version
Version: ImageMagick 7.0.8-62 Q16 x64 2019-08-24 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2018 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Visual C++: 180040629
Features: Cipher DPC Modules OpenCL OpenMP(2.0)
Delegates (built-in): bzlib cairo flif freetype gslib heic jng jp2 jpeg lcms lqr lzma openexr pangocairo png ps raw rsvg tiff webp xml zlib

Sorry if I do a poor job of explaining this.

I have a PNG with transparent and translucent pixels:

I'd like to convert it to GIF, but "mogrify -format gif input.png" gives an ugly result:

I'd like to fill behind all translucent (but not fully transparent) pixels with an opaque color (white), and then convert to get this result:

Is there any way to do this in ImageMagick?

Thank you for your help!

Pudlo wrote:I'd like to fill behind all translucent (but not fully transparent) pixels with an opaque color (white), ...

This does what you ask for (Windows syntax):

Code: Select all

magick j86x4XQ.png ( -clone 0 -background White -layers Flatten ) ( -clone 0 -alpha extract -threshold 0 ) -delete 0 -alpha off -compose CopyOpacity -composite filltrans.gif

We flatten the entire image against white, then we make fully transparent just those pixels that were originally fully transparent.

There is a white halo around the circle because the input had anti-aliased alpha.

Hey, thanks so much! You're a wizard.

For anybody reading this in the future, I had to backslash escape the brackets:

Code: Select all

magick j86x4XQ.png \( -clone 0 -background White -layers Flatten \) \( -clone 0 -alpha extract -threshold 0 \) -delete 0 -alpha off -compose CopyOpacity -composite filltrans.png

Note that Unix syntax is different from Windows syntax in that regard.

Legacy ImageMagick Discussions Archive

Fill behind all translucent (but not fully transparent) pixels

Fill behind all translucent (but not fully transparent) pixels

Re: Fill behind all translucent (but not fully transparent) pixels

Re: Fill behind all translucent (but not fully transparent) pixels

Re: Fill behind all translucent (but not fully transparent) pixels