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How to save a greyscale RGB picture with alpha channel?

Posted: 2009-07-27T06:57:30-07:00
by jho
Hi,
i had a strange problem. I had a picture (16bit tiff) which contains several grey colors. I simply want to compress the picture.
I typed the following:

convert grey.tif -compress zip grey_new.tif

The problem is that the new tif is stored as greyscale with alpha but i want it to be RGB or simply the same as the input.
When I convert a colorful picture it uses RGBA as I want.

I tried to use "-type TrueColorMatte" but it stays greyscale without alpha. When I use "-type TrueColor" I get it in the RGB mode but without the alpha channel.

Does anyone have an idea?

Re: How to save a greyscale RGB picture with alpha channel?

Posted: 2009-07-27T07:24:27-07:00
by magick
We can reproduce the problem you posted and have a patch. The patch will be available in the next point release of ImageMagick. Thanks.

Re: How to save a greyscale RGB picture with alpha channel?

Posted: 2009-07-27T07:47:39-07:00
by jho
Wow, what a fast response time! :shock:

I used the current portable version.

Thank you.

Re: How to save a greyscale RGB picture with alpha channel?

Posted: 2009-08-04T01:09:24-07:00
by jho
Great, it works now. Good work. Thank you very much. 8)