Ximagic Quantizer

Ximagic Quantizer is a graphic plugin which enables you to configure color quantization settings, in order to reduce colors from your photos. It can also be used for image dithering. 8-bit and 16-bit images are supported.

Primarily developed for Photoshop, the plugin is compatible with a wide range of hosts, such as Paint.NET, IrfanView, XnView, GIMP, Pixia, Fireworks, ArcSoft Photo Studio and Zoner Photo Studio. Setting it up is just a matter of moving the downloaded file to the host's plugins directory, depending on the program you have installed.

It's wrapped in a user-friendly interface that shows the original, filtered and difference images in separate panes. You can select the color space between RGB, YCbCr and Lab, as well as pick the quantization mode between a predefined (3-, 6-, 9-, 12- or 3-3-2-bit RGB) or a custom palette by loading text PAL or ACT files (Paint Shop Pro palette or Adobe Color Table).

Alternatively, you can opt for calculated palette mode to adjust the colors, bits and settings for the preferred quantization technique: uniform RGB, popularity, median cut, octree, Wu, Denis Lee 3, binary split, k-means, NeuQuant, or spatial color.

The tool can be asked to perform calculations from the selection and apply them to the whole image. Error dithering is enabled by default, and you can tweak the propagation rate, as well as set the queue size for the space filling curve method (Riemersma) or opt for one of the eight array patterns available: Floyd-Steinberg, Ulichney, Fan, Jarvis, Stucki, or Sierra (3, 2, 24A), with or without serpentine scanning. Moreover, the app can calculate the RMSE.

It's possible to save multiple previews to compare them before choosing one to apply to the picture. Worth noting is that, while Ximagic Quantizer is capable of reducing the number of colors, it cannot transform an RGB image into an indexed color.

To wrap it up, Ximagic Quantizer provides advanced users with a simple environment for configuring color quantization and dither settings while previewing changes and, although it's mainly developed for Photoshop, the utility is compatible with numerous host applications.