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Transparent needed in newer version of IM?
Posted: 2010-11-18T14:05:28-07:00
by mapdude
Trying to convert postscript files to jpegs; on one machine with ImageMagick 6.5.9 Q16 installed, the marginalia (which is supposed to be visible) is blacked out. On another machine with ImageMagick 6.3.1 QB installed it works properly. I'm using the following command on both machines:
Code: Select all
convert -contrast-stretch 1% -geometry 250 -quality 90 -density 144 loc.ps ..\*target_fire_ID*_loc_250.jpg
Am I supposed to include some sort of -transparent switch in the newer version of IM?
Re: Transparent needed in newer version of IM?
Posted: 2010-11-18T22:09:22-07:00
by anthony
JPG does not understand transparency!
See JPG Transparency - NOT!
http://www.imagemagick.org/Usage/format ... #jpg_trans
Also look at; Basics, Remove Alpha Transparency
http://www.imagemagick.org/Usage/basics/#alpha_remove
Re: Transparent needed in newer version of IM?
Posted: 2010-11-19T15:10:56-07:00
by mapdude
But why different results in the different versions? Does this mean the alpha transparency wasn't applicable in earlier versions and now I need to include it while using a newer version of IM?
Re: Transparent needed in newer version of IM?
Posted: 2010-11-19T16:07:04-07:00
by fmw42
jpg never supported transparency. it is not an IM thing.
Re: Transparent needed in newer version of IM?
Posted: 2010-11-21T19:47:49-07:00
by anthony
On the other hand the newer JPEG2000 image file format does support transparency (or so I'm told).
But that is not the JPEG format that most people use.