Legacy ImageMagick Discussions Archive

I'm trying to convert 8bpp bitmaps to 1bpp for use with a receipt printer. I can get the correct depth thusly: However, this gives me a colormap where 0 => black and 1 => white. The printer, stupidly, ignores the palette in the file and assumes 1 is black. Is there any way to either invert the colormap in the 1bpp file, or explicitly define the colormap during conversion from 8bpp to 1bpp?

What about just inverting the colors?

convert -monochrome -colors 2 -depth 1 -negate source.bmp out.bmp

Negate actually inverts the colormap as well as the pixels - so the print out doesn't change, unfortunately. I want to switch just the pixels OR just the colormap, not both.

try converting to tiff, then set the min is white or black flag to swap that and then convert to bmp. see http://www.imagemagick.org/Usage/formats/#tiff


toggle the photometric interpretation (Added IM 6.3.2-10)
-define quantum:polarity=min-is-black
-define quantum:polarity=min-is-white

Also note that proper IM 6 syntax generally has the input image right after convert, except for things like controls for vector to raster format, such a colorspace and density. see http://www.imagemagick.org/Usage/basics/#why

Are you using a foxjet or similar monochrome printhead?

I played with this and I found that -remap test.bmp, where test.bmp has the right palette works well..