I'm using imagemagick convert to convert this image https://i.stack.imgur.com/u4z85.jpg to a bmp. However for some reason the tool I am using doesn't like the bitmap. If I save the image as a png and convert it to a 24bit bmp its fine. I tried using the following command bit it doesn't like it.
convert -verbose -depth 8 -type truecolor infile outfile.bmp
Looking at the file I see that the 'bad' bmp has
BMÊp1 (0's) Š
The good one has
BMvp1 (0's) 6
I have had some trouble with BMP conversions too. I have typically specified BMP3:outfile.bmp and I normally get 24 bit BMP files. sometimes I get an 8 bit BMP when converting JPEG files. I just tried the -type truecolor (having seen it here) and now it looks like I get a 24 bit BMP in the cases where I used to get only 8 bits.
I also use these switches:
-units PixelsPerInch -density 72 -compress None -depth 24
the -depth 24 should do a 24 bit BMP (the depth -8 in your case may also be causing a problem) but as I said I sometimes get 8 bits even with the 24 specified.
the -units and -density cases corrected a problem where sometimes I would get a 0 for the biXPelsPerMeter and biYPelsPerMeter fields in the BMP header (it did not seem to cause a problem though). by the way I have not found a good explanation of these 2 fields.
the -compress None was required because sometimes a conversion generated a compressed BMP - no logical reason for doing that was found.
hopefully this will be of some help but I am not an expert on this subject - I just tried a few things and looked around using Google and came up with the above switch settings.
