ImageGear for C and C++ on Windows v20.0 - Updated
IG_IP_color_reduce_diffuse
API Reference Guide > Core Component API Reference > Core Component Functions Reference > Image Processing Functions > IG_IP_color_reduce_diffuse

This function reduces the image to a fewer number of Bits Per Pixel.

Declaration:

 
Copy Code
AT_ERRCOUNT ACCUAPI IG_IP_color_reduce_diffuse ( 
        HIGEAR hIGear, 
        UINT nToBits, 
        INT level, 
        LPAT_RGBQUAD lpPalette 
);

Arguments:

Name Type Description
hIGear HIGEAR HIGEAR handle of image of which to reduce bit depth.
nToBits UINT Number of bits per pixel after reduction, 1 or 4.
Level INT Threshold value for dithering, 0 to 255. Has effect only if nToBits = 1.
lpPalette LPAT_RGBQUAD This argument is currently not used.

Return Value:

Returns the number of ImageGear errors that occurred during this function call.

Supported Raster Image Formats:

Indexed RGB – 4, 8 bpp;
Grayscale – 4, 8 bpp;
RGB – 24 bpp.

Sample:

None

Example:

 
Copy Code
HIGEAR hIGear;   /* HIGEAR handle of 4, 8, or 24 bit image */
/* Reduce image to 1-bit black-and-white: */
IG_IP_color_reduce_diffuse ( hIGear, 1, 128, NULL );

Remarks:

The target bit depth is specified by argument nToBits. In general, a color image will be reduced to a fewer number of colors, and a grayscale image will be reduced to a fewer number of shades of gray. Note that setting nToBits = 1 will reduce the image to monochrome or black-and-white.

When reducing the image to monochrome (black-and-white), the level parameter sets a threshold value for the target image:

The input number of Bits Per Pixel must be greater than nToBits, or an error will result.

See also section in entitled Color Reduction.
Is this page helpful?
Yes No
Thanks for your feedback.