Legacy ImageMagick Discussions Archive

To create 8 bit PNG images, use the PNG8 format:

• convert input.png png8:output.png

RGB images are generally 24 bits, 8 bits for each channel. If an alpha channel is included, the RGBA image is 32 bit. A 16-bit per channel image can be reduced to 8 with the -depth 8 option. To get a 8-bit image you need a single channel which requires the image is colormapped or grayscale. To get a colormapped image, use PNG8 as we suggested. For grayscale, use -type scale. If you use PNG8 and the Properties panel still says 32, the Properties panel is wrong and mostly has a bug.