Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
dognose
Posts: 265 Joined: 2005-03-08T22:16:37-07:00
Post
by dognose » 2019-10-08T07:20:06-07:00
Was using this in IM 6
How do i get a transparent background?
flower.jpg
convert flower.jpg -background transparent -shear 12x0 png:output.png
im 6.7.2
img 7.0.8
snibgo
Posts: 12159 Joined: 2010-01-23T23:01:33-07:00
Authentication code: 1151
Location: England, UK
Post
by snibgo » 2019-10-08T07:42:49-07:00
You need to enable alpha:
Code: Select all
magick flower.jpg -alpha set -background transparent -shear 12x0 out.png
dognose
Posts: 265 Joined: 2005-03-08T22:16:37-07:00
Post
by dognose » 2019-10-08T08:23:40-07:00
Ok, that works, but it's weird that in other places I use -background transparent it works without -set alpha!?
snibgo
Posts: 12159 Joined: 2010-01-23T23:01:33-07:00
Authentication code: 1151
Location: England, UK
Post
by snibgo » 2019-10-08T08:27:21-07:00
I suppose in those other cases alpha is already enabled. If the input image has any transparency, alpha will certainly be enabled.
dognose
Posts: 265 Joined: 2005-03-08T22:16:37-07:00
Post
by dognose » 2019-10-08T09:19:13-07:00
for example
convert flower.jpg -background transparent -rotate 45 out.png
will have a transparent background
you'd think setting a color to transparent would enable alpha.. or some consistency.
Anyway thanks for tip!