conversion of 24bit rgb image to 256 colors leaves bad pixel

[Jon]

take the rgb image (http://www.brickstores.com/misc/rgb.tif)

convert rgb.tif -colors 256 output.tif

6.4.9 windows convert gives http://www.brickstores.com/misc/6.4.9-256.tif
(which is broken - the magenta E has black pixels in it)

6.4.0 windows convert gives http://www.brickstores.com/misc/6.4.0-256.tif
(which is ok)

the same think happens if you just try to convert to a gif (convert rgb.tif rgb.gif)

[fmw42]

take the rgb image (http://www.brickstores.com/misc/rgb.tif)

convert rgb.tif -colors 256 output.tif

6.4.9 windows convert gives http://www.brickstores.com/misc/6.4.9-256.tif
(which is broken - the magenta E has black pixels in it)

6.4.0 windows convert gives http://www.brickstores.com/misc/6.4.0-256.tif
(which is ok)

the same think happens if you just try to convert to a gif (convert rgb.tif rgb.gif)

On IM 6.4.9-4 Q16 Mac OSX Tiger, this works fine.
convert rgb.tif -colors 256 output.tif

You might try adding +dither to turn off dithering and see if that helps on your system.

This also works fine.
convert rgb.tif rgb.gif

what minor version of IM 6.4.9 are you using? see

convert -list configure


try upgrading to 6.4.9-4

are you using Q16 or Q8?

[Jon]

i was using 6.4.9-2 Q8 build with vc6 (Debug release)
+dither doesn't help

6.4.9-4 also fails