User's Reference - QuantizeImage

### QuantizeImage

Category

Transformation

Function

Converts an RGB image to a byte image with a colormap

Syntax

    images = QuantizeImage(Images, nColors);

Inputs

Name | Type | Default | Description
--- | --- | --- | ---
`images` | image, image series | (none) | image(s) to quantize
`nColors` | integer | 256 | maximum number of colors to use

Outputs

Name | Type | Description
--- | --- | ---
`images` | image, image series | resulting quantized image(s)

Functional Details

QuantizeImage converts an image from a format in which the "colors" component is a list of RGB (red, green, blue) vectors, with as many entries as there are pixels in the image, to a format in which the "colors" component is simply a list of unsigned bytes which are interpreted as pointers into a color table.

QuantizeImage sets a "direct color map" attribute of 1 on its output. When the output `images` is passed to Display, this will force Display to use the colormap specified by QuantizeImage, rather than a default colormap (see "Using Direct Color Maps"). This will be the case even if you set the environment variable DX8BITCMAP to 1. You can use the Options module to set a "direct color map" attribute of 0 on the output of QuantizeImage to force Display to use a shared colormap.

`images` | is the image or series of images to be quantized.
`nColors` | is the maximum number of entries in the color table.

The output `images` will be a new image or series of images in which the color table is attached as a component called "color map".

The advantage of using QuantizeImage is that the image will consume much less memory.

Components

Changes the "colors" component. Adds a "color map" component.

Example Visual Programs

    SIMPLE/QuantizeImage.net

See Also

Render, ReadImage, WriteImage, Display, Options

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