[magick-users] Dithering does not work anymore

[Hermann Stainer]

Dear list members,

I am new to this list but using ImageMagick since a long time. It's 
really great software, but since today I have a serious problem:

The dithering seems not to work anymore!

While I am usually compiling IM by myself, there is one machine where 
I'm still using SuSE (I know...) and on this machine, until today I used 
the Yast2-Package of IM. It was the version 6.2.5.
So today I wanted to check out the "-unique-colors" parameter and 
therefore installed the newest version 6.4.0 from source. Everything 
seems to work fine so far, but the dithering is not working anymore.

I used the following command:

convert source.png -monochrome dest.png

This resulted in a nicely dithered black&white picture.

The same time, I made a non-dithered image:

convert source.png +dither -monochrome dest.png

This worked fine, too!

With the new version, I get the SAME image in both cases, and I would 
say that both are images with no dithering. I do not get the old nicely 
dithered image like in the old version 6.2.5.

On the "usage examples", it is said somewhere that "at the moment" 
"+dither" does not work with "-monochrome". What does that mean?

Why doesn't dithering work anymore? Did I make a mistake? Do I need any 
special parameter when compiling to get the nice old dithering function?

Any help would be very appriciated! Thank you very much in any case!!

Best regards,
Hermann