Tiff resize removes alpha channel

[theiviaxx]

Hello, i'm trying to use IM to resize images as its has some better options than PS. However if I have an RGBA TIFF and a simple:

Code: Select all

convert.exe source.tif -resize 1024x1024 dest.tif

Will essentially "bake" the alpha channel as transparency into the tiff and remove the alpha channel. I've tried the different -alpha settings, but nothing did the trick.

Is there a way to preserve the alpha channel?

Thanks

[fmw42]

Post a link to your tiff file. You can upload to say dropbox and put a link here to it.

If you do

identify -verbose source.tiff

does it show an alpha channel?

IM can only handle one or the other of background transparency and alpha channel. I do not recall which one it uses. So if you have the wrong one, you will lose the alpha channel when reading the image.

If IM sees the alpha channel, then try

convert source.tiff -alpha on -channel rgba -resize 1024x1024 dest.tif

My guess is that your tiff file has the wrong kind of transparency and IM does not see it.