[magick-users] is this a bug?

[Amadeus W. M.]

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!