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ADDITION

ADDITION

Section: C Library Functions (3) Updated: 24 April 1991
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NAME

im_add, im_gadd, im_gaddim, im_gfadd - add two images  

SYNOPSIS

#include <vips/vips.h>

int im_add(in1, in2, out)
IMAGE *in1, *in2, *out;

int im_gadd(a, in1, b, in2, c, out)
double a, b, c;
IMAGE *in1, *in2, *out;

int im_gaddim(a, in1, b, in2, c, out)
double a, b, c;
IMAGE *in1, *in2, *out;

int im_gfadd(a, in1, b, in2, c, out)
double a, b, c;
IMAGE *in1, *in2, *out;

 

DESCRIPTION

These functions operate on two images held by image descriptors in1 and in2 and write the result to the image descriptor out. Input images in1 and in2 should have the same channels and the same size; however they can be of different types. Only the history of the image descriptor pointed by in1 is copied to out.

im_add(3)

For two integer images, add the two images and write the output as


 in1    - uchar   char   ushort  short  uint  int 
 -------|-----------------------------------------
 in2    |
 uchar  | ushort  short  ushort  short  uint  int
 char   | short   short  short   short  int   int
 ushort | ushort  short  ushort  short  uint  int
 short  | short   short  short   short  int   int
 uint   | uint    int    uint    int    uint  int
 int    | int     int    int     int    int   int

If one or more of the images is a floating point type, the output is FMTFLOAT, unless one or more of the inputs is FMTDOUBLE, in which case the output is also FMTDOUBLE.

If one or more of the images is a complex type, the output is FMTCOMPLEX, unless one or more of the inputs is FMTDPCOMPLEX, in which case the output is also FMTDPCOMPLEX.

im_gadd(3) performs generalised addition of two images by calling im_gaddim(3) and im_gfadd(3). These are very old and tired things, and should not be used.

Input should be non complex. Output depends on input according to function called. The result at each point is: a * pel1 + b * pel2 + c, properly rounded if necessary. Pel1 and pel2 are the corresponding pixels from in1 and in2 respectively.

im_gaddim() performs generalised addition of in1 and in2, on the condition they are neither float nor double nor complex. The format of the resultant image is given by the table:


 in1    - uchar   char   ushort  short  uint  int 
 -------|-----------------------------------------
 in2    |
 uchar  | ushort  short  ushort  short  uint  int
 char   | short   short  short   short  int   int
 ushort | ushort  short  ushort  short  uint  int
 short  | short   short  short   short  int   int
 uint   | uint    int    uint    int    uint  int
 int    | int     int    int     int    int   int

The result at each point is: a * pel1 + b * pel2 + c, properly rounded. Pel1 and pel2 are the corresponding pixels from in1 and in2 respectively.

im_gfadd(3) adds the non-complex images pointed by in1 and in2. Result is float except if one (or both) inputs is double. In the latter case the result is double. The result at each point is: a * pel1 + b * pel2 + c. Pel1 and pel2 are the corresponding pixels from in1 and in2 respectively.

 

BUGS

None of the functions checks the result for over/underflow.  

RETURN VALUE

All functions return 0 on success and -1 on error.  

SEE ALSO

im_subtract(3), im_lintra(3), im_multiply(3).  

AUTHOR

N. Dessipris - 22/04/1991
J. Cupitt, im_add(), - 21/7/93


 

Index

NAME
SYNOPSIS
DESCRIPTION
BUGS
RETURN VALUE
SEE ALSO
AUTHOR

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Time: 21:48:18 GMT, April 16, 2011