static void
computeGrayscaleRow(const pixel * const inputRow,
gray * const outputRow,
pixval const maxval,
unsigned int const cols) {
if (maxval <= 255) {
unsigned int col;
/* Use fast approximation to 0.299 r + 0.587 g + 0.114 b. */
for (col = 0; col < cols; ++col)
outputRow[col] = ppm_fastlumin(inputRow[col]);
} else {
unsigned int col;
/* Can't use fast approximation, so fall back on floats. */
for (col = 0; col < cols; ++col)
outputRow[col] = PPM_LUMIN(inputRow[col]) + 0.5;
}
}
static acolorhist_vector
mediancut( acolorhist_vector achv, int colors, int sum, unsigned char maxval, int newcolors )
{
acolorhist_vector acolormap;
box_vector bv;
register int bi, i;
int boxes;
bv = (box_vector) malloc( sizeof(struct box) * newcolors );
acolormap =
(acolorhist_vector) malloc( sizeof(struct acolorhist_item) * newcolors);
if ( bv == (box_vector) 0 || acolormap == (acolorhist_vector) 0 ) {
fprintf( stderr, " out of memory allocating box vector\n" );
fflush(stderr);
exit(6);
}
for ( i = 0; i < newcolors; ++i )
PAM_ASSIGN( acolormap[i].acolor, 0, 0, 0, 0 );
/*
** Set up the initial box.
*/
bv[0].ind = 0;
bv[0].colors = colors;
bv[0].sum = sum;
boxes = 1;
/*
** Main loop: split boxes until we have enough.
*/
while ( boxes < newcolors ) {
register int indx, clrs;
int sm;
register int minr, maxr, ming, mina, maxg, minb, maxb, maxa, v;
int halfsum, lowersum;
/*
** Find the first splittable box.
*/
for ( bi = 0; bi < boxes; ++bi )
if ( bv[bi].colors >= 2 )
break;
if ( bi == boxes )
break; /* ran out of colors! */
indx = bv[bi].ind;
clrs = bv[bi].colors;
sm = bv[bi].sum;
/*
** Go through the box finding the minimum and maximum of each
** component - the boundaries of the box.
*/
minr = maxr = PAM_GETR( achv[indx].acolor );
ming = maxg = PAM_GETG( achv[indx].acolor );
minb = maxb = PAM_GETB( achv[indx].acolor );
mina = maxa = PAM_GETA( achv[indx].acolor );
for ( i = 1; i < clrs; ++i ) {
v = PAM_GETR( achv[indx + i].acolor );
if ( v < minr ) minr = v;
if ( v > maxr ) maxr = v;
v = PAM_GETG( achv[indx + i].acolor );
if ( v < ming ) ming = v;
if ( v > maxg ) maxg = v;
v = PAM_GETB( achv[indx + i].acolor );
if ( v < minb ) minb = v;
if ( v > maxb ) maxb = v;
v = PAM_GETA( achv[indx + i].acolor );
if ( v < mina ) mina = v;
if ( v > maxa ) maxa = v;
}
/*
** Find the largest dimension, and sort by that component. I have
** included two methods for determining the "largest" dimension;
** first by simply comparing the range in RGB space, and second
** by transforming into luminosities before the comparison. You
** can switch which method is used by switching the commenting on
** the LARGE_ defines at the beginning of this source file.
*/
#ifdef LARGE_NORM
if ( maxa - mina >= maxr - minr && maxa - mina >= maxg - ming && maxa - mina >= maxb - minb )
qsort(
(char*) &(achv[indx]), clrs, sizeof(struct acolorhist_item),
alphacompare );
else if ( maxr - minr >= maxg - ming && maxr - minr >= maxb - minb )
qsort(
(char*) &(achv[indx]), clrs, sizeof(struct acolorhist_item),
redcompare );
else if ( maxg - ming >= maxb - minb )
qsort(
(char*) &(achv[indx]), clrs, sizeof(struct acolorhist_item),
greencompare );
else
qsort(
(char*) &(achv[indx]), clrs, sizeof(struct acolorhist_item),
bluecompare );
#endif /*LARGE_NORM*/
#ifdef LARGE_LUM
{
apixel p;
float rl, gl, bl, al;
PAM_ASSIGN(p, maxr - minr, 0, 0, 0);
rl = PPM_LUMIN(p);
PAM_ASSIGN(p, 0, maxg - ming, 0, 0);
gl = PPM_LUMIN(p);
PAM_ASSIGN(p, 0, 0, maxb - minb, 0);
bl = PPM_LUMIN(p);
/*
GRR: treat alpha as grayscale and assign (maxa - mina) to each of R, G, B?
assign (maxa - mina)/3 to each?
use alpha-fractional luminosity? (normalized_alpha * lum(r,g,b))
al = dunno ...
[probably should read Heckbert's paper to decide]
*/
if ( al >= rl && al >= gl && al >= bl )
qsort(
(char*) &(achv[indx]), clrs, sizeof(struct acolorhist_item),
alphacompare );
else if ( rl >= gl && rl >= bl )
qsort(
(char*) &(achv[indx]), clrs, sizeof(struct acolorhist_item),
redcompare );
else if ( gl >= bl )
qsort(
(char*) &(achv[indx]), clrs, sizeof(struct acolorhist_item),
greencompare );
else
qsort(
(char*) &(achv[indx]), clrs, sizeof(struct acolorhist_item),
bluecompare );
}
#endif /*LARGE_LUM*/
/*
** Now find the median based on the counts, so that about half the
** pixels (not colors, pixels) are in each subdivision.
*/
lowersum = achv[indx].value;
halfsum = sm / 2;
for ( i = 1; i < clrs - 1; ++i ) {
if ( lowersum >= halfsum )
break;
lowersum += achv[indx + i].value;
}
/*
** Split the box, and sort to bring the biggest boxes to the top.
*/
bv[bi].colors = i;
bv[bi].sum = lowersum;
bv[boxes].ind = indx + i;
bv[boxes].colors = clrs - i;
bv[boxes].sum = sm - lowersum;
++boxes;
qsort( (char*) bv, boxes, sizeof(struct box), sumcompare );
}
/*
** Ok, we've got enough boxes. Now choose a representative color for
** each box. There are a number of possible ways to make this choice.
** One would be to choose the center of the box; this ignores any structure
** within the boxes. Another method would be to average all the colors in
** the box - this is the method specified in Heckbert's paper. A third
** method is to average all the pixels in the box. You can switch which
** method is used by switching the commenting on the REP_ defines at
** the beginning of this source file.
*/
for ( bi = 0; bi < boxes; ++bi ) {
#ifdef REP_CENTER_BOX
register int indx = bv[bi].ind;
register int clrs = bv[bi].colors;
register int minr, maxr, ming, maxg, minb, maxb, mina, maxa, v;
minr = maxr = PAM_GETR( achv[indx].acolor );
ming = maxg = PAM_GETG( achv[indx].acolor );
minb = maxb = PAM_GETB( achv[indx].acolor );
mina = maxa = PAM_GETA( achv[indx].acolor );
for ( i = 1; i < clrs; ++i ) {
v = PAM_GETR( achv[indx + i].acolor );
minr = min( minr, v );
maxr = max( maxr, v );
v = PAM_GETG( achv[indx + i].acolor );
ming = min( ming, v );
maxg = max( maxg, v );
v = PAM_GETB( achv[indx + i].acolor );
minb = min( minb, v );
maxb = max( maxb, v );
v = PAM_GETA( achv[indx + i].acolor );
mina = min( mina, v );
maxa = max( maxa, v );
}
PAM_ASSIGN(
acolormap[bi].acolor, ( minr + maxr ) / 2, ( ming + maxg ) / 2,
( minb + maxb ) / 2, ( mina + maxa ) / 2 );
#endif /*REP_CENTER_BOX*/
#ifdef REP_AVERAGE_COLORS
register int indx = bv[bi].ind;
register int clrs = bv[bi].colors;
register long r = 0, g = 0, b = 0, a = 0;
for ( i = 0; i < clrs; ++i ) {
r += PAM_GETR( achv[indx + i].acolor );
g += PAM_GETG( achv[indx + i].acolor );
b += PAM_GETB( achv[indx + i].acolor );
a += PAM_GETA( achv[indx + i].acolor );
}
r = r / clrs;
g = g / clrs;
b = b / clrs;
a = a / clrs;
PAM_ASSIGN( acolormap[bi].acolor, r, g, b, a );
#endif /*REP_AVERAGE_COLORS*/
#ifdef REP_AVERAGE_PIXELS
register int indx = bv[bi].ind;
register int clrs = bv[bi].colors;
register long r = 0, g = 0, b = 0, a = 0, sum = 0;
for ( i = 0; i < clrs; ++i ) {
r += PAM_GETR( achv[indx + i].acolor ) * achv[indx + i].value;
g += PAM_GETG( achv[indx + i].acolor ) * achv[indx + i].value;
b += PAM_GETB( achv[indx + i].acolor ) * achv[indx + i].value;
a += PAM_GETA( achv[indx + i].acolor ) * achv[indx + i].value;
sum += achv[indx + i].value;
}
if(sum>0) {
r = r / sum;
if ( r > maxval ) r = maxval; /* avoid math errors */
g = g / sum;
if ( g > maxval ) g = maxval;
b = b / sum;
if ( b > maxval ) b = maxval;
a = a / sum;
if ( a > maxval ) a = maxval;
} else {
r = g = b = a = maxval;
}
/* GRR 20001228: added casts to quiet warnings; 255 DEPENDENCY */
PAM_ASSIGN( acolormap[bi].acolor, (unsigned char)r, (unsigned char)g, (unsigned char)b, (unsigned char)a );
#endif /*REP_AVERAGE_PIXELS*/
}
/*
** All done.
*/
free(bv);
return acolormap;
}
static void
computeLuminosityHistogram(xel * const * const xels,
unsigned int const rows,
unsigned int const cols,
xelval const maxval,
int const format,
bool const monoOnly,
unsigned int ** const lumahistP,
xelval * const lminP,
xelval * const lmaxP,
unsigned int * const pixelCountP) {
/*----------------------------------------------------------------------------
Scan the image and build the luminosity histogram. If the input is
a PPM, we calculate the luminosity of each pixel from its RGB
components.
-----------------------------------------------------------------------------*/
xelval lmin, lmax;
unsigned int pixelCount;
unsigned int * lumahist;
MALLOCARRAY(lumahist, maxval + 1);
if (lumahist == NULL)
pm_error("Out of storage allocating array for %u histogram elements",
maxval + 1);
{
unsigned int i;
/* Initialize histogram to zeroes everywhere */
for (i = 0; i <= maxval; ++i)
lumahist[i] = 0;
}
lmin = maxval; /* initial value */
lmax = 0; /* initial value */
switch (PNM_FORMAT_TYPE(format)) {
case PGM_TYPE:
case PBM_TYPE: {
/* Compute intensity histogram */
unsigned int row;
pixelCount = rows * cols;
for (row = 0; row < rows; ++row) {
unsigned int col;
for (col = 0; col < cols; ++col) {
xelval const l = PNM_GET1(xels[row][col]);
lmin = MIN(lmin, l);
lmax = MAX(lmax, l);
++lumahist[l];
}
}
}
break;
case PPM_TYPE: {
unsigned int row;
for (row = 0, pixelCount = 0; row < rows; ++row) {
unsigned int col;
for (col = 0; col < cols; ++col) {
xel const thisXel = xels[row][col];
if (!monoOnly || PPM_ISGRAY(thisXel)) {
xelval const l = PPM_LUMIN(thisXel);
lmin = MIN(lmin, l);
lmax = MAX(lmax, l);
++lumahist[l];
++pixelCount;
}
}
}
}
break;
default:
pm_error("invalid input format format");
}
*lumahistP = lumahist;
*pixelCountP = pixelCount;
*lminP = lmin;
*lmaxP = lmax;
}
void thin1(bitmap_type *image, unsigned char colour)
{
unsigned char *ptr, *y_ptr, *y1_ptr;
unsigned char bg_color;
unsigned int xsize, ysize; /* Image resolution */
unsigned int x, y; /* Pixel location */
unsigned int i; /* Pass index */
unsigned int pc = 0; /* Pass count */
unsigned int count = 1; /* Deleted pixel count */
unsigned int p, q; /* Neighborhood maps of adjacent*/
/* cells */
unsigned char *qb; /* Neighborhood maps of previous*/
/* scanline */
unsigned int m; /* Deletion direction mask */
if (PPM_ISGRAY(background))
bg_color = PPM_GETR(background);
else
bg_color = PPM_LUMIN(background);
LOG (" Thinning image.....\n ");
xsize = image->width;
ysize = image->height;
MALLOCARRAY_NOFAIL(qb, xsize);
qb[xsize-1] = 0; /* Used for lower-right pixel */
ptr = image->bitmap;
while ( count ) { /* Scan image while deletions */
pc++;
count = 0;
for ( i = 0 ; i < 4 ; i++ ) {
m = masks[i];
/* Build initial previous scan buffer. */
p = (ptr[0] == colour);
for ( x = 0 ; x < xsize-1 ; x++ )
qb[x] = (unsigned char) (p = ((p<<1)&0006) | (unsigned int)(ptr[x+1] == colour));
/* Scan image for pixel deletion candidates. */
y_ptr = ptr; y1_ptr = ptr + xsize;
for (y = 0; y < ysize - 1; y++, y_ptr += xsize, y1_ptr += xsize)
{
q = qb[0];
p = ((q<<2)&0330) | (y1_ptr[0] == colour);
for ( x = 0 ; x < xsize-1 ; x++ ) {
q = qb[x];
p = ((p<<1)&0666) | ((q<<3)&0110) | (unsigned int) (y1_ptr[x+1]==colour);
qb[x] = (unsigned char) p;
if ( ((p&m) == 0) && todelete[p] ) {
count++;
y_ptr[x] = bg_color; /* delete the pixel */
}
}
/* Process right edge pixel. */
p = (p<<1)&0666;
if ( (p&m) == 0 && todelete[p] ) {
count++;
y_ptr[xsize-1] = bg_color;
}
}
/* Process bottom scan line. */
q = qb[0];
p = ((q<<2)&0330);
y_ptr = ptr + xsize * (ysize - 1);
for ( x = 0 ; x < xsize ; x++ ) {
q = qb[x];
p = ((p<<1)&0666) | ((q<<3)&0110);
if ( (p&m) == 0 && todelete[p] ) {
count++;
y_ptr[x] = bg_color;
}
}
}
LOG2("thin1: pass %d, %d pixels deleted\n", pc, count);
}
free (qb);
}
void
thin_image(bitmap_type *image, bool bgSpec, pixel bg,
at_exception_type * exp)
{
/* This is nasty as we need to call thin once for each
* colour in the image the way I do this is to keep a second
* copy of the bitmap and to use this to keep
* track of which colours have not yet been processed,
* trades time for pathological case memory.....*/
long m, n, num_pixels;
bitmap_type bm;
unsigned int const spp = image->np;
unsigned int const width = image->width;
unsigned int const height = image->height;
if (bgSpec)
background = bg;
else
PPM_ASSIGN(background, 255, 255, 255);
/* Clone the image */
bm.height = image->height;
bm.width = image->width;
bm.np = image->np;
MALLOCARRAY(bm.bitmap, height * width * spp);
if (bm.bitmap == NULL)
pm_error("Unable to get memory for thin image bitmap clone");
memcpy(bm.bitmap, image->bitmap, height * width * spp);
num_pixels = height * width;
switch (spp)
{
case 3:
{
Pixel *ptr = (Pixel*)bm.bitmap;
Pixel bg_color;
bg_color[0] = PPM_GETR(background);
bg_color[1] = PPM_GETG(background);
bg_color[2] = PPM_GETB(background);
for (n = num_pixels - 1; n >= 0L; --n)
{
Pixel p;
PIXEL_SET(p, ptr[n]);
if (!PIXEL_EQUAL(p, bg_color))
{
/* we have a new colour in the image */
LOG3("Thinning colour (%x, %x, %x)\n", p[0], p[1], p[2]);
for (m = n - 1; m >= 0L; --m)
{
if (PIXEL_EQUAL(ptr[m], p))
PIXEL_SET(ptr[m], bg_color);
}
thin3(image, p);
}
}
break;
}
case 1:
{
unsigned char * const ptr = bm.bitmap;
unsigned char bg_color;
if (PPM_ISGRAY(background))
bg_color = PPM_GETR(background);
else
bg_color = PPM_LUMIN(background);
for (n = num_pixels - 1; n >= 0L; --n)
{
unsigned char c = ptr[n];
if (c != bg_color)
{
LOG1 ("Thinning colour %x\n", c);
for (m = n - 1; m >= 0L; --m)
if (ptr[m] == c) ptr[m] = bg_color;
thin1(image, c);
}
}
break;
}
default:
{
LOG1 ("thin_image: %u-plane images are not supported", spp);
at_exception_fatal(exp, "thin_image: wrong plane images are passed");
goto cleanup;
}
}
cleanup:
free (bm.bitmap);
}