C:/Users/Malcolm/Documents/temp/binaryimagelibrary/halftone.c File Reference

#include <stdlib.h>
#include <assert.h>

Functions
unsigned char *	randomhalftone (unsigned char *grey, int width, int height)
unsigned char *	floydsteinberg (unsigned char *grey, int width, int height)
unsigned char *	stucki (unsigned char *grey, int width, int height)
unsigned char *	ordereddisperseddot (unsigned char *grey, int width, int height, int order)
unsigned char *	orderedclustereddot (unsigned char *grey, int width, int height, int order)

Detailed Description

Halftone functions.

Half toning is when we represent a greyscale iamge as a binary image, using filters and dithering to give a visual representation of the grey.

Margaret Thatcher (1925-2013) greyscale photograph

Function Documentation

unsigned char* floydsteinberg	(	unsigned char *	grey,
		int	width,
		int	height
	)

Halftoning with Floyd-Steinberg error diffusion.

Parameters

grey	- the greyscale image
width	- image width
height	- image height

Returns

Halftoned binary image.

unsigned char* orderedclustereddot	(	unsigned char *	grey,
		int	width,
		int	height,
		int	order
	)

Ordered clustered dot dithering.

Parameters

[in]	grey	- the greyscale image
	width	- image width
	height	- image height
	order	- 3, 4, or8

Returns

The dithered image.

order = 3

order = 4

order = 8

NB : The predefined dither matrices are the same as matrices used in the Netpbm package (http://netpbm.sourceforge.net) and are defined in Ulichney's book. See also : The newsprint web site at http://www.cl.cam.ac.uk/~and1000/newsprint/ for more technical info on this dithering technique

unsigned char* ordereddisperseddot	(	unsigned char *	grey,
		int	width,
		int	height,
		int	order
	)

Ordered dithering with a Bayer matrix of size 2^order by 2^order.

Parameters

grey	- the greycale image
width	- image width
height	- image height
order	- size of matrix (1-4)

Returns

halftoned binary image

order = 1

order = 2

order = 3

order = 4

unsigned char* randomhalftone	(	unsigned char *	grey,
		int	width,
		int	height
	)

Halftoning with random dither.

Parameters

grey	- the greyscale image
width	- image width
height	- image height

Returns

Halftoned binary image.

unsigned char* stucki	(	unsigned char *	grey,
		int	width,
		int	height
	)

Halftoning with Stucki error diffusion.

Parameters

grey	- the greyscale image
width	- image width
height	- image height

Returns

Halftoned binary image.