Transparent needed in newer version of IM?

[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?

[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

[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?

[fmw42]

jpg never supported transparency. it is not an IM thing.

[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.