[magick-users] Re: is this a bug?

[Amadeus W. M.]

On Wed, 10 Jan 2007 15:38:21 +1000, Anthony Thyssen wrote:

> "Amadeus W. M." on  wrote...
> | I'm trying to crop a a pgm image like this:
> | 
> | convert -crop 50x50 lena.pgm tmp.pgm
> | 
> | The resulting pgm has white value = 65535 rather than 255:
> | 
> | head -3 tmp.pgm
> | P5
> | 50 50
> | 65535
> | 
> | even though the original is ok:
> | 
> | head -3 lena.pgm 
> | P5
> | 208 222
> | 255
> | 
> | Also, the resulting tmp.pgm image has size 92722 bytes rather than
> | 50x50=2500 as I'd expect (without the header). Despite all this, xv
> | displays it correctly. I don't understand. What's going on? 
> | 
> | Thanks!
> | 
> You are using a Q16 version of IM which premotes all color values to 16
> bit quality (-depth 16).
> 
> The thrid line just says what the maximum value is for the data
> that follows.
> 
> If you want it 255 you can set   -depth 8    before saving the PGM file.
> 

I saw the -depth option after I posted. Thanks for the answer. Forgive my
ignorance, what is a Q16 version of IM? For what it's worth, I'm on a
Fedora Core 6 system on and

rpm -q ImageMagick
ImageMagick-6.2.8.0-3.fc6.1

Do I have a choice? I want depth 8 by default. The thing of it is I've been
using convert for a long time, on a fairly regular basis, and I never
noticed the depth problem/feature. There was a recent IM update, maybe
they changed to Q16.