Legacy ImageMagick Discussions Archive

Because this thread got a good number of views and still left me a bit puzzled, I believe I found a rather simple solution as outlined here:

http://blog.schdbr.de/imagemagic-osx-static-relocatable-build/

In short, this is quite easy using homebrew:

brew edit imagemagick
in def install:
--disable ...

I have done some research here:
http://blog.schdbr.de/imagemagic-osx-static-relocatable-build/

TL;DR: Use homebrew,
brew edit imagemagick
in def install:
--disable-shared to disallow shared libs
brew install imagemagick --without-modules --with-zero-configuration

gave me what I wanted (including ...

As for the data, it is indeed a bit of a special case. In the 3d/games industry some programs or game engines use the alpha channel in normal maps to define the specularity of a material/shader. This saves memory as one does not need an extra texture to hold a greyscale image only. That way, using ...

Fantastic, thanks a lot for clearing this up!

I agree that in most cases colored pixels are less important where alpha is zero.
On the other hand, in many scientifical and highend (although im is pretty highend, too) programs like houdini / shake / nuke every image channel is treated equally ...

Sure!

http://madprocessor.de/files/in.tga
the first, unaltered file. You should see a red image when viewed with display -alpha off in.tga .

http://madprocessor.de/files/out.tga
the same file, still tga, just resized by one pixel in x/y. You should see text.

You have to display the images ...

convert in.tga out.tga does retain the colors, as convert in.tga out.tif does.

convert in.tga -resize 1024x1024 out.tif also does not retain the colors where a=0.

Just for clarification, the alpha is always retained, just the rgb colors are missing where alpha is absolutely zero.


I am not sure ...

I am using convert to scale images (actually normal map video game textures containing the specularity in the alpha channel).

if i do a convert in.tga out.tif the out.tif looks as expected (alpha and color channels intact).
if i do a convert -resize 1024x1024 in.tga out.tif the color information is ...