1MACROS(3)                  Library Functions Manual                  MACROS(3)
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NAME

6       IM_IMAGE_ADDR,       IM_IMAGE_SIZEOF_ELEMENT,      IM_IMAGE_SIZEOF_PEL,
7       IM_IMAGE_SIZEOF_LINE, IM_IMAGE_N_ELEMENTS - macros for images
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SYNOPSIS

10       #include <vips/vips.h>
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12       int IM_IMAGE_SIZEOF_ELEMENT( im )
13       IMAGE *im;
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15       int IM_IMAGE_SIZEOF_PEL( im )
16       IMAGE *im;
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18       int IM_IMAGE_SIZEOF_LINE( im )
19       IMAGE *im;
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21       int IM_IMAGE_N_ELEMENTS( im )
22       IMAGE *im;
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24       char *IM_IMAGE_ADDR( im, x, y )
25       IMAGE *im;
26       int x;
27       int y;
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DESCRIPTION

31       These macros help to simplify address arithmetic for images.
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33       IM_IMAGE_SIZEOF_ELEMENT(3) returns sizeof( one band element ).
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35       IM_IMAGE_SIZEOF_PEL(3) returns sizeof( one pel ).
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37       IM_IMAGE_SIZEOF_LINE(3) returns sizeof( one horizontal line of pels ).
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39       IM_IMAGE_N_ELEMENTS(3) returns the number of  band  elements  across  a
40       horizontal line.
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42       IM_IMAGE_ADDR(3)  returns  a  pointer to the pixel at position (x,y) in
43       the image. The point (x,y) should lie within the image.
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45       If the macro DEBUG has been defined, then  IM_IMAGE_ADDR(3)  will  also
46       perform  bounds  checking.  If you ask for the address of a pel outside
47       the image, then IM_IMAGE_ADDR(3) will print an  error  message  of  the
48       form:
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50           IM_IMAGE_ADDR: point out of bounds, file "test.c", line 18
51           (point x=50, y=0
52            should have been within Rect left=0, top=0, width=50, height=50)
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54       and call abort(3).
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56       DEBUG  needs  to  be defined *before* vips.h is included. Either define
57       DEBUG with -D in your Makefile, or have a #define DEBUG  right  at  the
58       top of your file.
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61       National Gallery, 1993
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SEE ALSO

64       im_malloc(3),  im_open_local(3),  `VIPS  Library Programmers' Guide' in
65       accompanying documentation.
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AUTHOR

68       J. Cupitt - 23/7/93
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72                                 11 April 1990                       MACROS(3)
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