First define the preferred number of colors in your image.
The actual number of colors in the image may be less
than your request, but never more. Note, this is a
color reduction option. Images with less unique
colors than specified with this option will have any duplicate
or unused colors removed.
Refer to
quantize
for more details.
You also have a choice of several options that affect your image colormap.
Choose from these options:
- dither
- apply Floyd/Steinberg error diffusion to the image.
The basic strategy of dithering is to trade intensity
resolution for spatial resolution by averaging the
intensities of several neighboring pixels. Images
which suffer from severe contouring when reducing
colors can be improved with this option.
- black & white
- transform the image to black and white.
- global colormap
- create a single colormap for a sequence of images.
- netscape color cube
- map image to web safe colors.
- map to clipboard
- map image to clipboard colors.
- gray image
- transform the image to gray colors.
- segment
- segment an image by analyzing the histograms of the color
components and identifying units that are homogeneous with the fuzzy c-means
technique.
- preserve transparent pixels
- by default color reduction does not preserve and transparent pixels
in your image. Choose this option to reduce the number of colors in your
image while preserving any transparent pixels.