Simple interface for grayscale image arithmetic. More...

#include <stdio.h>
#include <stdlib.h>
#include "allheaders.h"

Functions
PIXACC *	pixaccCreate (l_int32 w, l_int32 h, l_int32 negflag)
PIXACC *	pixaccCreateWithPix (PIX *pix, l_int32 negflag)
void	pixaccDestroy (PIXACC **ppixacc)
PIX *	pixaccFinal (PIXACC *pixacc, l_int32 outdepth)
PIX *	pixaccGetPix (PIXACC *pixacc)
l_int32	pixaccGetOffset (PIXACC *pixacc)
l_int32	pixaccAdd (PIXACC pixacc, PIX pix)
l_int32	pixaccSubtract (PIXACC pixacc, PIX pix)
l_int32	pixaccMultConst (PIXACC *pixacc, l_float32 factor)
l_int32	pixaccMultConstAccumulate (PIXACC pixacc, PIX pix, l_float32 factor)

Detailed Description

Simple interface for grayscale image arithmetic.

    Pixacc creation, destruction
         PIXACC   *pixaccCreate()
         PIXACC   *pixaccCreateWithPix()
         void      pixaccDestroy()

    Pixacc finalization
         PIX      *pixaccFinal()

    Pixacc accessors
         PIX      *pixaccGetPix()
         l_int32   pixaccGetOffset()

    Pixacc accumulators
         l_int32   pixaccAdd()
         l_int32   pixaccSubtract()
         l_int32   pixaccMultConst()
         l_int32   pixaccMultConstAccumulate()

This is a simple interface for some of the pixel arithmetic operations 
in pixarith.c.  These are easy to code up, but not as fast as
hand-coded functions that do arithmetic on corresponding pixels.

Suppose you want to make a linear combination of pix1 and pix2:
   pixd = 0.4 * pix1 + 0.6 * pix2
where pix1 and pix2 are the same size and have depth 'd'.  Then:
   Pixacc *pacc = pixaccCreateWithPix(pix1, 0);  // first; addition only
   pixaccMultConst(pacc, 0.4);
   pixaccMultConstAccumulate(pacc, pix2, 0.6);  // Add in 0.6 of the second
   pixd = pixaccFinal(pacc, d);  // Get the result
   pixaccDestroy(&pacc);

Definition in file pixacc.c.

Function Documentation

PIXACC* pixaccCreate	(	l_int32	w,
		l_int32	h,
		l_int32	negflag
	)

pixaccCreate()

Input: w, h (of 32 bpp internal Pix) negflag (0 if only positive numbers are involved; 1 if there will be negative numbers) Return: pixacc, or null on error

Notes: (1) Use = 1 for safety if any negative numbers are going to be used in the chain of operations. Negative numbers arise, e.g., by subtracting a pix, or by adding a pix that has been pre-multiplied by a negative number. (2) Initializes the internal 32 bpp pix, similarly to the initialization in pixInitAccumulate().

Definition at line 77 of file pixacc.c.

References CALLOC, ERROR_PTR, Pixacc::h, NULL, Pixacc::offset, Pixacc::pix, pixCreate(), pixSetAllArbitrary(), PROCNAME, and Pixacc::w.

Referenced by main(), pixaccCreateWithPix(), pixaccMultConstAccumulate(), pixCompareTiled(), and pixUnsharpMaskingGray().