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Clean-up of sandbox, rearranging everything.

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Added a couple of files that was never commited.
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Harald Kuhr
2010-06-07 09:55:35 +02:00
parent 1f60b62626
commit b6ee5ce450
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common/common-image/src/main/java/com/twelvemonkeys/image/inv_cmap.c
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/*
* This software is copyrighted as noted below. It may be freely copied,
* modified, and redistributed, provided that the copyright notice is
* preserved on all copies.
*
* There is no warranty or other guarantee of fitness for this software,
* it is provided solely "as is". Bug reports or fixes may be sent
* to the author, who may or may not act on them as he desires.
*
* You may not include this software in a program or other software product
* without supplying the source, or without informing the end-user that the
* source is available for no extra charge.
*
* If you modify this software, you should include a notice giving the
* name of the person performing the modification, the date of modification,
* and the reason for such modification.
*/
/*
* inv_cmap.c - Compute an inverse colormap.
*
* Author: Spencer W. Thomas
* EECS Dept.
* University of Michigan
* Date: Thu Sep 20 1990
* Copyright (c) 1990, University of Michigan
*
* $Id: inv_cmap.c,v 3.0.1.3 1992/04/30 14:07:28 spencer Exp $
*/
#include <math.h>
#include <stdio.h>
static int bcenter, gcenter, rcenter;
static long gdist, rdist, cdist;
static long cbinc, cginc, crinc;
static unsigned long *gdp, *rdp, *cdp;
static unsigned char *grgbp, *rrgbp, *crgbp;
static gstride, rstride;
static long x, xsqr, colormax;
static int cindex;
#ifdef USE_PROTOTYPES
static void maxfill( unsigned long *, long );
static int redloop( void );
static int greenloop( int );
static int blueloop( int );
#else
static void maxfill();
static int redloop();
static int greenloop();
static int blueloop();
#endif
/*****************************************************************
* TAG( inv_cmap )
*
* Compute an inverse colormap efficiently.
* Inputs:
* colors: Number of colors in the forward colormap.
* colormap: The forward colormap.
* bits: Number of quantization bits. The inverse
* colormap will have (2^bits)^3 entries.
* dist_buf: An array of (2^bits)^3 long integers to be
* used as scratch space.
* Outputs:
* rgbmap: The output inverse colormap. The entry
* rgbmap[(r<<(2*bits)) + (g<<bits) + b]
* is the colormap entry that is closest to the
* (quantized) color (r,g,b).
* Assumptions:
* Quantization is performed by right shift (low order bits are
* truncated). Thus, the distance to a quantized color is
* actually measured to the color at the center of the cell
* (i.e., to r+.5, g+.5, b+.5, if (r,g,b) is a quantized color).
* Algorithm:
* Uses a "distance buffer" algorithm:
* The distance from each representative in the forward color map
* to each point in the rgb space is computed. If it is less
* than the distance currently stored in dist_buf, then the
* corresponding entry in rgbmap is replaced with the current
* representative (and the dist_buf entry is replaced with the
* new distance).
*
* The distance computation uses an efficient incremental formulation.
*
* Distances are computed "outward" from each color. If the
* colors are evenly distributed in color space, the expected
* number of cells visited for color I is N^3/I.
* Thus, the complexity of the algorithm is O(log(K) N^3),
* where K = colors, and N = 2^bits.
*/
/*
* Here's the idea: scan from the "center" of each cell "out"
* until we hit the "edge" of the cell -- that is, the point
* at which some other color is closer -- and stop. In 1-D,
* this is simple:
* for i := here to max do
* if closer then buffer[i] = this color
* else break
* repeat above loop with i := here-1 to min by -1
*
* In 2-D, it's trickier, because along a "scan-line", the
* region might start "after" the "center" point. A picture
* might clarify:
* | ...
* | ... .
* ... .
* ... | .
* . + .
* . .
* . .
* .........
*
* The + marks the "center" of the above region. On the top 2
* lines, the region "begins" to the right of the "center".
*
* Thus, we need a loop like this:
* detect := false
* for i := here to max do
* if closer then
* buffer[..., i] := this color
* if !detect then
* here = i
* detect = true
* else
* if detect then
* break
*
* Repeat the above loop with i := here-1 to min by -1. Note that
* the "detect" value should not be reinitialized. If it was
* "true", and center is not inside the cell, then none of the
* cell lies to the left and this loop should exit
* immediately.
*
* The outer loops are similar, except that the "closer" test
* is replaced by a call to the "next in" loop; its "detect"
* value serves as the test. (No assignment to the buffer is
* done, either.)
*
* Each time an outer loop starts, the "here", "min", and
* "max" values of the next inner loop should be
* re-initialized to the center of the cell, 0, and cube size,
* respectively. Otherwise, these values will carry over from
* one "call" to the inner loop to the next. This tracks the
* edges of the cell and minimizes the number of
* "unproductive" comparisons that must be made.
*
* Finally, the inner-most loop can have the "if !detect"
* optimized out of it by splitting it into two loops: one
* that finds the first color value on the scan line that is
* in this cell, and a second that fills the cell until
* another one is closer:
* if !detect then {needed for "down" loop}
* for i := here to max do
* if closer then
* buffer[..., i] := this color
* detect := true
* break
* for i := i+1 to max do
* if closer then
* buffer[..., i] := this color
* else
* break
*
* In this implementation, each level will require the
* following variables. Variables labelled (l) are local to each
* procedure. The ? should be replaced with r, g, or b:
* cdist: The distance at the starting point.
* ?center: The value of this component of the color
* c?inc: The initial increment at the ?center position.
* ?stride: The amount to add to the buffer
* pointers (dp and rgbp) to get to the
* "next row".
* min(l): The "low edge" of the cell, init to 0
* max(l): The "high edge" of the cell, init to
* colormax-1
* detect(l): True if this row has changed some
* buffer entries.
* i(l): The index for this row.
* ?xx: The accumulated increment value.
*
* here(l): The starting index for this color. The
* following variables are associated with here,
* in the sense that they must be updated if here
* is changed.
* ?dist: The current distance for this level. The
* value of dist from the previous level (g or r,
* for level b or g) initializes dist on this
* level. Thus gdist is associated with here(b)).
* ?inc: The initial increment for the row.
* ?dp: Pointer into the distance buffer. The value
* from the previous level initializes this level.
* ?rgbp: Pointer into the rgb buffer. The value
* from the previous level initializes this level.
*
* The blue and green levels modify 'here-associated' variables (dp,
* rgbp, dist) on the green and red levels, respectively, when here is
* changed.
*/
void
inv_cmap( colors, colormap, bits, dist_buf, rgbmap )
int colors, bits;
unsigned char *colormap[3], *rgbmap;
unsigned long *dist_buf;
{
int nbits = 8 - bits;
colormax = 1 << bits;
x = 1 << nbits;
xsqr = 1 << (2 * nbits);
/* Compute "strides" for accessing the arrays. */
gstride = colormax;
rstride = colormax * colormax;
maxfill( dist_buf, colormax );
for ( cindex = 0; cindex < colors; cindex++ )
{
/*
* Distance formula is
* (red - map[0])^2 + (green - map[1])^2 + (blue - map[2])^2
*
* Because of quantization, we will measure from the center of
* each quantized "cube", so blue distance is
* (blue + x/2 - map[2])^2,
* where x = 2^(8 - bits).
* The step size is x, so the blue increment is
* 2*x*blue - 2*x*map[2] + 2*x^2
*
* Now, b in the code below is actually blue/x, so our
* increment will be 2*(b*x^2 + x^2 - x*map[2]). For
* efficiency, we will maintain this quantity in a separate variable
* that will be updated incrementally by adding 2*x^2 each time.
*/
/* The initial position is the cell containing the colormap
* entry. We get this by quantizing the colormap values.
*/
rcenter = colormap[0][cindex] >> nbits;
gcenter = colormap[1][cindex] >> nbits;
bcenter = colormap[2][cindex] >> nbits;
rdist = colormap[0][cindex] - (rcenter * x + x/2);
gdist = colormap[1][cindex] - (gcenter * x + x/2);
cdist = colormap[2][cindex] - (bcenter * x + x/2);
cdist = rdist*rdist + gdist*gdist + cdist*cdist;
crinc = 2 * ((rcenter + 1) * xsqr - (colormap[0][cindex] * x));
cginc = 2 * ((gcenter + 1) * xsqr - (colormap[1][cindex] * x));
cbinc = 2 * ((bcenter + 1) * xsqr - (colormap[2][cindex] * x));
/* Array starting points. */
cdp = dist_buf + rcenter * rstride + gcenter * gstride + bcenter;
crgbp = rgbmap + rcenter * rstride + gcenter * gstride + bcenter;
(void)redloop();
}
}
/* redloop -- loop up and down from red center. */
static int
redloop()
{
int detect;
int r;
int first;
long txsqr = xsqr + xsqr;
static long rxx;
detect = 0;
/* Basic loop up. */
for ( r = rcenter, rdist = cdist, rxx = crinc,
rdp = cdp, rrgbp = crgbp, first = 1;
r < colormax;
r++, rdp += rstride, rrgbp += rstride,
rdist += rxx, rxx += txsqr, first = 0 )
{
if ( greenloop( first ) )
detect = 1;
else if ( detect )
break;
}
/* Basic loop down. */
for ( r = rcenter - 1, rxx = crinc - txsqr, rdist = cdist - rxx,
rdp = cdp - rstride, rrgbp = crgbp - rstride, first = 1;
r >= 0;
r--, rdp -= rstride, rrgbp -= rstride,
rxx -= txsqr, rdist -= rxx, first = 0 )
{
if ( greenloop( first ) )
detect = 1;
else if ( detect )
break;
}
return detect;
}
/* greenloop -- loop up and down from green center. */
static int
greenloop( restart )
int restart;
{
int detect;
int g;
int first;
long txsqr = xsqr + xsqr;
static int here, min, max;
static long ginc, gxx, gcdist; /* "gc" variables maintain correct */
static unsigned long *gcdp; /* values for bcenter position, */
static unsigned char *gcrgbp; /* despite modifications by blueloop */
/* to gdist, gdp, grgbp. */
if ( restart )
{
here = gcenter;
min = 0;
max = colormax - 1;
ginc = cginc;
}
detect = 0;
/* Basic loop up. */
for ( g = here, gcdist = gdist = rdist, gxx = ginc,
gcdp = gdp = rdp, gcrgbp = grgbp = rrgbp, first = 1;
g <= max;
g++, gdp += gstride, gcdp += gstride, grgbp += gstride, gcrgbp += gstride,
gdist += gxx, gcdist += gxx, gxx += txsqr, first = 0 )
{
if ( blueloop( first ) )
{
if ( !detect )
{
/* Remember here and associated data! */
if ( g > here )
{
here = g;
rdp = gcdp;
rrgbp = gcrgbp;
rdist = gcdist;
ginc = gxx;
}
detect = 1;
}
}
else if ( detect )
{
break;
}
}
/* Basic loop down. */
for ( g = here - 1, gxx = ginc - txsqr, gcdist = gdist = rdist - gxx,
gcdp = gdp = rdp - gstride, gcrgbp = grgbp = rrgbp - gstride,
first = 1;
g >= min;
g--, gdp -= gstride, gcdp -= gstride, grgbp -= gstride, gcrgbp -= gstride,
gxx -= txsqr, gdist -= gxx, gcdist -= gxx, first = 0 )
{
if ( blueloop( first ) )
{
if ( !detect )
{
/* Remember here! */
here = g;
rdp = gcdp;
rrgbp = gcrgbp;
rdist = gcdist;
ginc = gxx;
detect = 1;
}
}
else if ( detect )
{
break;
}
}
return detect;
}
/* blueloop -- loop up and down from blue center. */
static int
blueloop( restart )
int restart;
{
int detect;
register unsigned long *dp;
register unsigned char *rgbp;
register long bdist, bxx;
register int b, i = cindex;
register long txsqr = xsqr + xsqr;
register int lim;
static int here, min, max;
static long binc;
if ( restart )
{
here = bcenter;
min = 0;
max = colormax - 1;
binc = cbinc;
}
detect = 0;
/* Basic loop up. */
/* First loop just finds first applicable cell. */
for ( b = here, bdist = gdist, bxx = binc, dp = gdp, rgbp = grgbp, lim = max;
b <= lim;
b++, dp++, rgbp++,
bdist += bxx, bxx += txsqr )
{
if ( *dp > bdist )
{
/* Remember new 'here' and associated data! */
if ( b > here )
{
here = b;
gdp = dp;
grgbp = rgbp;
gdist = bdist;
binc = bxx;
}
detect = 1;
break;
}
}
/* Second loop fills in a run of closer cells. */
for ( ;
b <= lim;
b++, dp++, rgbp++,
bdist += bxx, bxx += txsqr )
{
if ( *dp > bdist )
{
*dp = bdist;
*rgbp = i;
}
else
{
break;
}
}
/* Basic loop down. */
/* Do initializations here, since the 'find' loop might not get
* executed.
*/
lim = min;
b = here - 1;
bxx = binc - txsqr;
bdist = gdist - bxx;
dp = gdp - 1;
rgbp = grgbp - 1;
/* The 'find' loop is executed only if we didn't already find
* something.
*/
if ( !detect )
for ( ;
b >= lim;
b--, dp--, rgbp--,
bxx -= txsqr, bdist -= bxx )
{
if ( *dp > bdist )
{
/* Remember here! */
/* No test for b against here necessary because b <
* here by definition.
*/
here = b;
gdp = dp;
grgbp = rgbp;
gdist = bdist;
binc = bxx;
detect = 1;
break;
}
}
/* The 'update' loop. */
for ( ;
b >= lim;
b--, dp--, rgbp--,
bxx -= txsqr, bdist -= bxx )
{
if ( *dp > bdist )
{
*dp = bdist;
*rgbp = i;
}
else
{
break;
}
}
/* If we saw something, update the edge trackers. */
return detect;
}
static void
maxfill( buffer, side )
unsigned long *buffer;
long side;
{
register unsigned long maxv = ~0L;
register long i;
register unsigned long *bp;
for ( i = side * side * side, bp = buffer;
i > 0;
i--, bp++ )
*bp = maxv;
}