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restore buildlut fix

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This commit is contained in:
John Cupitt 2009-08-18 11:34:50 +00:00
parent 97f1c38bef
commit 3c61a4c204
1 changed files with 21 additions and 10 deletions
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31
libvips/histograms_lut/im_buildlut.c
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@ -5,13 +5,18 @@
* @(#)
* @(#) we generate
* @(#)
* @(#) 0 0
* @(#) 1 0.4
* @(#) index value
* @(#) 0 0
* @(#) 1 0.4
* @(#) .. etc. linear interpolation
* @(#) 255 100
* @(#) 255 100
* @(#)
* @(#) (we don't generate the index column, that's just there to show the
* @(#) position in the table)
* @(#)
* @(#) The x/y points don't need to be sorted: we do that. You can have
* @(#) several Ys ... each becomes a band in the output LUT.
* @(#) several Ys: each becomes a band in the output LUT. You don't need to
* @(#) start at zero: any integer will do, including negatives.
*
* Written on: 26/9/06
* - from im_invertlut()
@ -21,6 +26,8 @@
* - saner limit and rounding behaviour
* 30/3/09
* - argh, fixed again
* 22/6/09
* - more fixes for tables that don't start at zero (thanks Jack)
*/
/*
@ -49,6 +56,10 @@
*/
/*
#define DEBUG
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
@ -64,14 +75,11 @@
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
/*
#define DEBUG
*/
/* Our state.
*/
typedef struct _State {
DOUBLEMASK *input; /* Input mask */
int xlow; /* Index 0 in output is this x */
int lut_size; /* Number of output elements to generate */
double **data; /* Rows of unpacked matrix */
double *buf; /* Ouput buffer */
@ -138,6 +146,7 @@ build_state( State *state, DOUBLEMASK *input )
if( v > xhigh )
xhigh = v;
}
state->xlow = xlow;
state->lut_size = xhigh - xlow + 1;
if( state->lut_size < 1 ) {
@ -183,10 +192,12 @@ build_state( State *state, DOUBLEMASK *input )
static int
buildlut( State *state )
{
const int xlow = state->xlow;
const DOUBLEMASK *input = state->input;
const int ysize = input->ysize;
const int xsize = input->xsize;
const int bands = xsize - 1;
const int xlast = state->data[ysize - 1][0];
int b, i, x;
@ -202,13 +213,13 @@ buildlut( State *state )
const double dy = y2 - y1;
for( x = 0; x < dx; x++ )
state->buf[b + (x + x1) * bands] =
state->buf[b + (x + x1 - xlow) * bands] =
y1 + x * dy / dx;
}
/* We are inclusive: pop the final value in by hand.
*/
state->buf[b + (int) state->data[ysize - 1][0] * bands] =
state->buf[b + (xlast - xlow) * bands] =
state->data[ysize - 1][b + 1];
}