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/*
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; File: wrap.c
;;; Author: Eero Simoncelli
;;; Description: Circular convolution on 2D images.
;;; Creation Date: Spring, 1987.
;;; MODIFICATIONS:
;;; 6/96: Switched array types to double float.
;;; 2/97: made more robust and readable. Added STOP arguments.
;;; ----------------------------------------------------------------
;;; Object-Based Vision and Image Understanding System (OBVIUS),
;;; Copyright 1988, Vision Science Group, Media Laboratory,
;;; Massachusetts Institute of Technology.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
*/
#include <stdlib.h>
#include "convolve.h"
/*
--------------------------------------------------------------------
Performs correlation (i.e., convolution with filt(-x,-y)) of FILT
with IMAGE followed by subsampling (a.k.a. REDUCE in Burt&Adelson81).
The operations are combined to avoid unnecessary computation of the
convolution samples that are to be discarded in the subsampling
operation. The convolution is done in 9 sections so that mod
operations are not performed unnecessarily. The subsampling lattice
is specified by the START, STEP and STOP parameters.
-------------------------------------------------------------------- */
/* abstract out the inner product computation */
#define INPROD(YSTART,YIND,XSTART,XIND) \
{ \
sum=0.0; \
for (y_im=YSTART, filt_pos=0, x_filt_stop=x_fdim; \
x_filt_stop<=filt_size; \
y_im++, x_filt_stop+=x_fdim) \
for (x_im=XSTART ; \
filt_pos<x_filt_stop; \
filt_pos++, x_im++) \
sum += imval[YIND][XIND] * filt[filt_pos]; \
result[res_pos] = sum; \
}
int internal_wrap_reduce(image, x_dim, y_dim, filt, x_fdim, y_fdim,
x_start, x_step, x_stop, y_start, y_step, y_stop,
result)
register image_type *filt, *result;
register int x_dim, y_dim, x_fdim, y_fdim;
image_type *image;
int x_start, x_step, x_stop, y_start, y_step, y_stop;
{
register double sum;
register int filt_size = x_fdim*y_fdim;
image_type **imval;
register int filt_pos, x_im, y_im, x_filt_stop;
register int x_pos, y_pos, res_pos;
int x_ctr_stop = x_dim - x_fdim + 1;
int y_ctr_stop = y_dim - y_fdim + 1;
int x_ctr_start = 0;
int y_ctr_start = 0;
int x_fmid = x_fdim/2;
int y_fmid = y_fdim/2;
/* shift start/stop coords to filter upper left hand corner */
x_start -= x_fmid; y_start -= y_fmid;
x_stop -= x_fmid; y_stop -= y_fmid;
if (x_stop < x_ctr_stop) x_ctr_stop = x_stop;
if (y_stop < y_ctr_stop) y_ctr_stop = y_stop;
/* Set up pointer array for rows */
imval = (image_type **) malloc(y_dim*sizeof(image_type *));
if (imval IS NULL)
{
printf("INTERNAL_WRAP: Failed to allocate temp array!");
return(-1);
}
for (y_pos=y_im=0;y_pos<y_dim;y_pos++,y_im+=x_dim)
imval[y_pos] = (image+y_im);
for (res_pos=0, y_pos=y_start; /* TOP ROWS */
y_pos<y_ctr_start;
y_pos+=y_step)
{
for (x_pos=x_start;
x_pos<x_ctr_start;
x_pos+=x_step, res_pos++)
INPROD(y_pos+y_dim, y_im%y_dim, x_pos+x_dim, x_im%x_dim)
for (;
x_pos<x_ctr_stop;
x_pos+=x_step, res_pos++)
INPROD(y_pos+y_dim, y_im%y_dim, x_pos, x_im)
for (;
x_pos<x_stop;
x_pos+=x_step, res_pos++)
INPROD(y_pos+y_dim, y_im%y_dim, x_pos, x_im%x_dim)
} /* end TOP ROWS */
for (; /* MID ROWS */
y_pos<y_ctr_stop;
y_pos+=y_step)
{
for (x_pos=x_start;
x_pos<x_ctr_start;
x_pos+=x_step, res_pos++)
INPROD(y_pos, y_im, x_pos+x_dim, x_im%x_dim)
for (; /* CENTER SECTION */
x_pos<x_ctr_stop;
x_pos+=x_step, res_pos++)
INPROD(y_pos, y_im, x_pos, x_im)
for (;
x_pos<x_stop;
x_pos+=x_step, res_pos++)
INPROD(y_pos, y_im, x_pos, x_im%x_dim)
} /* end MID ROWS */
for (; /* BOTTOM ROWS */
y_pos<y_stop;
y_pos+=y_step)
{
for (x_pos=x_start;
x_pos<x_ctr_start;
x_pos+=x_step, res_pos++)
INPROD(y_pos, y_im%y_dim, x_pos+x_dim, x_im%x_dim)
for (;
x_pos<x_ctr_stop;
x_pos+=x_step, res_pos++)
INPROD(y_pos, y_im%y_dim, x_pos, x_im)
for (;
x_pos<x_stop;
x_pos+=x_step, res_pos++)
INPROD(y_pos, y_im%y_dim, x_pos, x_im%x_dim)
} /* end BOTTOM ROWS */
free ((image_type **) imval);
return(0);
} /* end of internal_wrap_reduce */
/*
--------------------------------------------------------------------
Performs upsampling (padding with zeros) followed by convolution of
FILT with IMAGE (a.k.a. EXPAND in Burt&Adelson81). The operations
are combined to avoid unnecessary multiplication of filter samples
with zeros in the upsampled image. The convolution is done in 9
sections so that mod operation is not performed unnecessarily.
Arguments are described in the comment above internal_wrap_reduce.
WARNING: this subroutine destructively modifes the RESULT image, so
the user must zero the result before invocation!
-------------------------------------------------------------------- */
/* abstract out the inner product computation */
#define INPROD2(YSTART,YIND,XSTART,XIND) \
{ \
val = image[im_pos]; \
for (y_res=YSTART, filt_pos=0, x_filt_stop=x_fdim; \
x_filt_stop<=filt_size; \
y_res++, x_filt_stop+=x_fdim) \
for (x_res=XSTART; \
filt_pos<x_filt_stop; \
filt_pos++, x_res++) \
imval[YIND][XIND] += val * filt[filt_pos]; \
}
int internal_wrap_expand(image, filt, x_fdim, y_fdim,
x_start, x_step, x_stop, y_start, y_step, y_stop,
result, x_dim, y_dim)
register image_type *filt, *result;
register int x_fdim, y_fdim, x_dim, y_dim;
image_type *image;
int x_start, x_step, x_stop, y_start, y_step, y_stop;
{
register double val;
register int filt_size = x_fdim*y_fdim;
image_type **imval;
register int filt_pos, x_res, y_res, x_filt_stop;
register int x_pos, y_pos, im_pos;
int x_ctr_stop = x_dim - x_fdim + 1;
int y_ctr_stop = y_dim - y_fdim + 1;
int x_ctr_start = 0;
int y_ctr_start = 0;
int x_fmid = x_fdim/2;
int y_fmid = y_fdim/2;
/* shift start/stop coords to filter upper left hand corner */
x_start -= x_fmid; y_start -= y_fmid;
x_stop -= x_fmid; y_stop -= y_fmid;
if (x_stop < x_ctr_stop) x_ctr_stop = x_stop;
if (y_stop < y_ctr_stop) y_ctr_stop = y_stop;
/* Set up pointer array for rows */
imval = (image_type **) malloc(y_dim*sizeof(image_type *));
if (imval IS NULL)
{
printf("INTERNAL_WRAP: Failed to allocate temp array!");
return(-1);
}
for (y_pos=y_res=0;y_pos<y_dim;y_pos++,y_res+=x_dim)
imval[y_pos] = (result+y_res);
for (im_pos=0, y_pos=y_start; /* TOP ROWS */
y_pos<y_ctr_start;
y_pos+=y_step)
{
for (x_pos=x_start;
x_pos<x_ctr_start;
x_pos+=x_step, im_pos++)
INPROD2(y_pos+y_dim, y_res%y_dim, x_pos+x_dim, x_res%x_dim)
for (;
x_pos<x_ctr_stop;
x_pos+=x_step, im_pos++)
INPROD2(y_pos+y_dim, y_res%y_dim, x_pos, x_res)
for (;
x_pos<x_stop;
x_pos+=x_step, im_pos++)
INPROD2(y_pos+y_dim, y_res%y_dim, x_pos, x_res%x_dim)
} /* end TOP ROWS */
for (; /* MID ROWS */
y_pos<y_ctr_stop;
y_pos+=y_step)
{
for (x_pos=x_start;
x_pos<x_ctr_start;
x_pos+=x_step, im_pos++)
INPROD2(y_pos, y_res, x_pos+x_dim, x_res%x_dim)
for (; /* CENTER SECTION */
x_pos<x_ctr_stop;
x_pos+=x_step, im_pos++)
INPROD2(y_pos, y_res, x_pos, x_res)
for (;
x_pos<x_stop;
x_pos+=x_step, im_pos++)
INPROD2(y_pos, y_res, x_pos, x_res%x_dim)
} /* end MID ROWS */
for (; /* BOTTOM ROWS */
y_pos<y_stop;
y_pos+=y_step)
{
for (x_pos=x_start;
x_pos<x_ctr_start;
x_pos+=x_step, im_pos++)
INPROD2(y_pos, y_res%y_dim, x_pos+x_dim, x_res%x_dim)
for (;
x_pos<x_ctr_stop;
x_pos+=x_step, im_pos++)
INPROD2(y_pos, y_res%y_dim, x_pos, x_res)
for (;
x_pos<x_stop;
x_pos+=x_step, im_pos++)
INPROD2(y_pos, y_res%y_dim, x_pos, x_res%x_dim)
} /* end BOTTOM ROWS */
free ((image_type **) imval);
return(0);
} /* end of internal_wrap_expand */
/* Local Variables: */
/* buffer-read-only: t */
/* End: */
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