Quantize Filter

The Quantize filter converts any format image file to Quantize format, or vice versa. The Quantize filter reduces the number of colors used in an image for display on reduced palette displays (for example, video game machines). Quantize can either create a reduced color colormap or use an existing colormap.

You can also use the standalone quantizer aquant (see aquant in the Alias Standalone Utilities Guide online documentation).

To use the Quantize filter:

1

Select Render > Filter > Quantize. The File Requestor appears and prompts you to enter the source file name.

2

Type the name of the source file in the File Requestor, or click Show List and select the source file using the File Lister, and then click Pix file.

The source file is converted and saved as <sourcefilename>_quant.

To open the Quantize Options window:

• Select Render > Filter > Quantize .

Quantize Options

Frame Options

Application

Determines whether a single frame is converted (SINGLE), or an entire animation is converted (SEQUENCE). If Application is SEQUENCE, then the Start, End, By, and Extension size parameters become available. The default setting is SINGLE.

If Application is SEQUENCE and a colormap is being generated (for example, if the Input field of the Colormap options is empty), the quantizer reads in all images of the animation before creating the colormap. This allows a colormap to be generated for a sequence of frames whose dominant colors may change over time.

Quantize is very memory-intensive. If a colormap is being generated, then specifying too many files when file names are requested may cause the quantizer to run out of memory

Start, End, By

The first frame (Start), last frame (End), and frame increment (By) of the animation to be converted. The frame number is appended to each file name. These parameters are only available if Application is SEQUENCE. For example, if the Start value is 1, the End value is 20, the By value is 1, and the output file name is pixfile, then the actual output file names will be pixfile.1, pixfile.2, ..., pixfile.20. The default value is 1.

Extension size

The total number of characters in file name extensions. If the frame number is less than the Extension size value, then leading zeros are added to the extension. For example, if the Extension size value is 3, and the file name is pixfile, the actual file names will be pixfile.001, pixfile.002, and so on. If Extension size is 1, the actual file names will be pixfile.1, pixfile.2, and so on. This parameter is only available if Application is SEQUENCE. The slider range is 1 to 6. The default value is 1.

Quantization Options

Dither

Dithers the quantized image. Dithering examines the difference (error) between the real color and the quantized color, then distributes the difference to the surrounding pixels, which have not yet been quantized. The default setting is None.

Floyd/Steinberg	the standard Floyd/Steinberg dither distributes 3/8ths of the error to the pixel on the right and the pixel below, and 2/8ths to the pixel on the bottom right
Modified F/S	the modified Floyd/Steinberg dither distributes 7/16ths of the error to the right pixel, 5/16ths to the pixel below, 3/16ths to the pixel on the bottom left, and 1/16th to the pixel on the bottom right.
None	no dithering

Average Deviation

Uses the average deviation of pixels in a certain color range to split colors when creating the color lookup table. If Average Deviation is OFF, quantization uses the number of pixels in a certain color range to split colors when creating the color lookup table (the median cut method). If Average Deviation is OFF and quantization does not produce acceptable results, set Average Deviation ON. The default setting is OFF.

Bit depth

Determines the number of colors to be used in the quantized image. The slider range is 1 (2 colors) to 16 (65536 colors). The default setting is 8 (256 colors).

Colormap Options

The Colormap Options let you use an existing colormap, or save the colormap generated by Quantize. A colormap file contains n+1 lines of plain text, where n is the number of colors in the colormap. The first line of the file is cmap colors n. All other lines consist of three integer values (between 0 and 255) representing the RGB values of a color that is in the colormap. For example, a 4 color colormap would look like this:

cmap colors 4

231 233 238

96 94 108

1 29 128

2 2 6

You can produce an example of a colormap file by entering an Output file name, quantizing an image, and then editing the Output file.

Input

The file name of the colormap to be used for all input files. If you do not specify the colormap (that is, if Input is blank), Quantize automatically generates a colormap based on all input image files.

Output

The file name that the colormap generated by Quantize will be saved as. If you do not specify an output colormap file name, the colormap will not be saved.

Other Options

Store TIFF

Outputs the image file(s) in TIFF colormap image format. Only 8 bits/pixel TIFF files can be generated. The default setting is OFF.

Black elimination

Determines whether black pixels are considered when creating the colormap, and whether black pixels are quantized to (0,0,1) when outputting the image.

Off	black pixels (0,0,0) are considered when creating the colormap, and unchanged when outputting the image
Input	black pixels (0,0,0) are ignored when creating the colormap, and unchanged when outputting the image
Output	black pixels (0,0,0) are considered when creating the colormap, and quantized to (0,0,1) when outputting the image
Input and Output	black pixels are ignored when creating the colormap, and quantized to (0,0,1) when outputting the image

Verbose

Provides feedback on the quantization by writing diagnostic information in the errlog. The default setting is OFF (no diagnostics).