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/*
* The Python Imaging Library
* $Id$
*
* various special effects and image generators
*
* history:
* 1997-05-21 fl Just for fun
* 1997-06-05 fl Added mandelbrot generator
* 2003-05-24 fl Added perlin_turbulence generator (in progress)
*
* Copyright (c) 1997-2003 by Fredrik Lundh.
* Copyright (c) 1997 by Secret Labs AB.
*
* See the README file for information on usage and redistribution.
*/
#include "Imaging.h"
#include <math.h>
Imaging
ImagingEffectMandelbrot(int xsize, int ysize, double extent[4], int quality)
{
/* Generate a Mandelbrot set covering the given extent */
Imaging im;
int x, y, k;
double width, height;
double x1, y1, xi2, yi2, cr, ci, radius;
double dr, di;
/* Check arguments */
width = extent[2] - extent[0];
height = extent[3] - extent[1];
if (width < 0.0 || height < 0.0 || quality < 2)
return (Imaging) ImagingError_ValueError(NULL);
im = ImagingNew("L", xsize, ysize);
if (!im)
return NULL;
dr = width/(xsize-1);
di = height/(ysize-1);
radius = 100.0;
for (y = 0; y < ysize; y++) {
UINT8* buf = im->image8[y];
for (x = 0; x < xsize; x++) {
x1 = y1 = xi2 = yi2 = 0.0;
cr = x*dr + extent[0];
ci = y*di + extent[1];
for (k = 1;; k++) {
y1 = 2*x1*y1 + ci;
x1 = xi2 - yi2 + cr;
xi2 = x1*x1;
yi2 = y1*y1;
if ((xi2 + yi2) > radius) {
buf[x] = k*255/quality;
break;
}
if (k > quality) {
buf[x] = 0;
break;
}
}
}
}
return im;
}
Imaging
ImagingEffectNoise(int xsize, int ysize, float sigma)
{
/* Generate gaussian noise centered around 128 */
Imaging imOut;
int x, y;
int nextok;
double this, next;
imOut = ImagingNew("L", xsize, ysize);
if (!imOut)
return NULL;
next = 0.0;
nextok = 0;
for (y = 0; y < imOut->ysize; y++) {
UINT8* out = imOut->image8[y];
for (x = 0; x < imOut->xsize; x++) {
if (nextok) {
this = next;
nextok = 0;
} else {
/* after numerical recepies */
double v1, v2, radius, factor;
do {
v1 = rand()*(2.0/32767.0) - 1.0;
v2 = rand()*(2.0/32767.0) - 1.0;
radius= v1*v1 + v2*v2;
} while (radius >= 1.0);
factor = sqrt(-2.0*log(radius)/radius);
this = factor * v1;
next = factor * v2;
}
out[x] = (unsigned char) (128 + sigma * this);
}
}
return imOut;
}
Imaging
ImagingEffectPerlinTurbulence(int xsize, int ysize)
{
/* Perlin turbulence (In progress) */
return NULL;
}
Imaging
ImagingEffectSpread(Imaging imIn, int distance)
{
/* Randomly spread pixels in an image */
Imaging imOut;
int x, y;
imOut = ImagingNew(imIn->mode, imIn->xsize, imIn->ysize);
if (!imOut)
return NULL;
#define SPREAD(type, image)\
for (y = 0; y < imIn->ysize; y++)\
for (x = 0; x < imIn->xsize; x++) {\
int xx = x + (rand() % distance) - distance/2;\
int yy = y + (rand() % distance) - distance/2;\
if (xx >= 0 && xx < imIn->xsize && yy >= 0 && yy < imIn->ysize) {\
imOut->image[yy][xx] = imIn->image[y][x];\
imOut->image[y][x] = imIn->image[yy][xx];\
} else\
imOut->image[y][x] = imIn->image[y][x];\
}
if (imIn->image8) {
SPREAD(UINT8, image8);
} else {
SPREAD(INT32, image32);
}
ImagingCopyInfo(imOut, imIn);
return imOut;
}
/* -------------------------------------------------------------------- */
/* Taken from the "C" code in the W3C SVG specification. Translated
to C89 by Fredrik Lundh */
#if 0
/* Produces results in the range [1, 2**31 - 2].
Algorithm is: r = (a * r) mod m
where a = 16807 and m = 2**31 - 1 = 2147483647
See [Park & Miller], CACM vol. 31 no. 10 p. 1195, Oct. 1988
To test: the algorithm should produce the result 1043618065
as the 10,000th generated number if the original seed is 1.
*/
#define RAND_m 2147483647 /* 2**31 - 1 */
#define RAND_a 16807 /* 7**5; primitive root of m */
#define RAND_q 127773 /* m / a */
#define RAND_r 2836 /* m % a */
static long
perlin_setup_seed(long lSeed)
{
if (lSeed <= 0) lSeed = -(lSeed % (RAND_m - 1)) + 1;
if (lSeed > RAND_m - 1) lSeed = RAND_m - 1;
return lSeed;
}
static long
perlin_random(long lSeed)
{
long result;
result = RAND_a * (lSeed % RAND_q) - RAND_r * (lSeed / RAND_q);
if (result <= 0) result += RAND_m;
return result;
}
#define BSize 0x100
#define BM 0xff
#define PerlinN 0x1000
#define NP 12 /* 2^PerlinN */
#define NM 0xfff
static int perlin_uLatticeSelector[BSize + BSize + 2];
static double perlin_fGradient[4][BSize + BSize + 2][2];
typedef struct
{
int nWidth; /* How much to subtract to wrap for stitching. */
int nHeight;
int nWrapX; /* Minimum value to wrap. */
int nWrapY;
} StitchInfo;
static void
perlin_init(long lSeed)
{
double s;
int i, j, k;
lSeed = perlin_setup_seed(lSeed);
for(k = 0; k < 4; k++)
{
for(i = 0; i < BSize; i++)
{
perlin_uLatticeSelector[i] = i;
for (j = 0; j < 2; j++)
perlin_fGradient[k][i][j] = (double)(((lSeed = perlin_random(lSeed)) % (BSize + BSize)) - BSize) / BSize;
s = (double) (sqrt(perlin_fGradient[k][i][0] * perlin_fGradient[k][i][0] + perlin_fGradient[k][i][1] * perlin_fGradient[k][i][1]));
perlin_fGradient[k][i][0] /= s;
perlin_fGradient[k][i][1] /= s;
}
}
while(--i)
{
k = perlin_uLatticeSelector[i];
perlin_uLatticeSelector[i] = perlin_uLatticeSelector[j = (lSeed = perlin_random(lSeed)) % BSize];
perlin_uLatticeSelector[j] = k;
}
for(i = 0; i < BSize + 2; i++)
{
perlin_uLatticeSelector[BSize + i] = perlin_uLatticeSelector[i];
for(k = 0; k < 4; k++)
for(j = 0; j < 2; j++)
perlin_fGradient[k][BSize + i][j] = perlin_fGradient[k][i][j];
}
}
#define s_curve(t) ( t * t * (3. - 2. * t) )
#define lerp(t, a, b) ( a + t * (b - a) )
static double
perlin_noise2(int nColorChannel, double vec[2], StitchInfo *pStitchInfo)
{
int bx0, bx1, by0, by1, b00, b10, b01, b11;
double rx0, rx1, ry0, ry1, *q, sx, sy, a, b, t, u, v;
register int i, j;
t = vec[0] + (double) PerlinN;
bx0 = (int)t;
bx1 = bx0+1;
rx0 = t - (int)t;
rx1 = rx0 - 1.0f;
t = vec[1] + (double) PerlinN;
by0 = (int)t;
by1 = by0+1;
ry0 = t - (int)t;
ry1 = ry0 - 1.0f;
/* If stitching, adjust lattice points accordingly. */
if(pStitchInfo != NULL)
{
if(bx0 >= pStitchInfo->nWrapX)
bx0 -= pStitchInfo->nWidth;
if(bx1 >= pStitchInfo->nWrapX)
bx1 -= pStitchInfo->nWidth;
if(by0 >= pStitchInfo->nWrapY)
by0 -= pStitchInfo->nHeight;
if(by1 >= pStitchInfo->nWrapY)
by1 -= pStitchInfo->nHeight;
}
bx0 &= BM;
bx1 &= BM;
by0 &= BM;
by1 &= BM;
i = perlin_uLatticeSelector[bx0];
j = perlin_uLatticeSelector[bx1];
b00 = perlin_uLatticeSelector[i + by0];
b10 = perlin_uLatticeSelector[j + by0];
b01 = perlin_uLatticeSelector[i + by1];
b11 = perlin_uLatticeSelector[j + by1];
sx = (double) (s_curve(rx0));
sy = (double) (s_curve(ry0));
q = perlin_fGradient[nColorChannel][b00]; u = rx0 * q[0] + ry0 * q[1];
q = perlin_fGradient[nColorChannel][b10]; v = rx1 * q[0] + ry0 * q[1];
a = lerp(sx, u, v);
q = perlin_fGradient[nColorChannel][b01]; u = rx0 * q[0] + ry1 * q[1];
q = perlin_fGradient[nColorChannel][b11]; v = rx1 * q[0] + ry1 * q[1];
b = lerp(sx, u, v);
return lerp(sy, a, b);
}
double
perlin_turbulence(
int nColorChannel, double *point, double fBaseFreqX, double fBaseFreqY,
int nNumOctaves, int bFractalSum, int bDoStitching,
double fTileX, double fTileY, double fTileWidth, double fTileHeight)
{
StitchInfo stitch;
StitchInfo *pStitchInfo = NULL; /* Not stitching when NULL. */
double fSum = 0.0f;
double vec[2];
double ratio = 1;
int nOctave;
vec[0] = point[0] * fBaseFreqX;
vec[1] = point[1] * fBaseFreqY;
/* Adjust the base frequencies if necessary for stitching. */
if(bDoStitching)
{
/* When stitching tiled turbulence, the frequencies must be adjusted */
/* so that the tile borders will be continuous. */
if(fBaseFreqX != 0.0)
{
double fLoFreq = (double) (floor(fTileWidth * fBaseFreqX)) / fTileWidth;
double fHiFreq = (double) (ceil(fTileWidth * fBaseFreqX)) / fTileWidth;
if(fBaseFreqX / fLoFreq < fHiFreq / fBaseFreqX)
fBaseFreqX = fLoFreq;
else
fBaseFreqX = fHiFreq;
}
if(fBaseFreqY != 0.0)
{
double fLoFreq = (double) (floor(fTileHeight * fBaseFreqY)) / fTileHeight;
double fHiFreq = (double) (ceil(fTileHeight * fBaseFreqY)) / fTileHeight;
if(fBaseFreqY / fLoFreq < fHiFreq / fBaseFreqY)
fBaseFreqY = fLoFreq;
else
fBaseFreqY = fHiFreq;
}
/* Set up initial stitch values. */
pStitchInfo = &stitch;
stitch.nWidth = (int) (fTileWidth * fBaseFreqX + 0.5f);
stitch.nWrapX = (int) (fTileX * fBaseFreqX + PerlinN + stitch.nWidth);
stitch.nHeight = (int) (fTileHeight * fBaseFreqY + 0.5f);
stitch.nWrapY = (int) (fTileY * fBaseFreqY + PerlinN + stitch.nHeight);
}
for(nOctave = 0; nOctave < nNumOctaves; nOctave++)
{
if(bFractalSum)
fSum += (double) (perlin_noise2(nColorChannel, vec, pStitchInfo) / ratio);
else
fSum += (double) (fabs(perlin_noise2(nColorChannel, vec, pStitchInfo)) / ratio);
vec[0] *= 2;
vec[1] *= 2;
ratio *= 2;
if(pStitchInfo != NULL)
{
/* Update stitch values. Subtracting PerlinN before the multiplication and */
/* adding it afterward simplifies to subtracting it once. */
stitch.nWidth *= 2;
stitch.nWrapX = 2 * stitch.nWrapX - PerlinN;
stitch.nHeight *= 2;
stitch.nWrapY = 2 * stitch.nWrapY - PerlinN;
}
}
return fSum;
}
#endif
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