Pillow/libImaging/BoxBlur.c

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#include "Python.h"
#include "Imaging.h"
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#define MAX(x, y) (((x) > (y)) ? (x) : (y))
#define MIN(x, y) (((x) < (y)) ? (x) : (y))
typedef UINT8 pixel[4];
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void static inline
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ImagingLineBoxBlur32(pixel *lineOut, pixel *lineIn, int lastx, int radius, int edgeA,
int edgeB, UINT32 ww, UINT32 fw)
{
int x;
UINT32 acc[4];
UINT32 bulk[4];
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#define MOVE_ACC(acc, subtract, add) \
acc[0] += lineIn[add][0] - lineIn[subtract][0]; \
acc[1] += lineIn[add][1] - lineIn[subtract][1]; \
acc[2] += lineIn[add][2] - lineIn[subtract][2]; \
acc[3] += lineIn[add][3] - lineIn[subtract][3];
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#define ADD_FAR(bulk, acc, left, right) \
bulk[0] = (acc[0] * ww) + (lineIn[left][0] + lineIn[right][0]) * fw; \
bulk[1] = (acc[1] * ww) + (lineIn[left][1] + lineIn[right][1]) * fw; \
bulk[2] = (acc[2] * ww) + (lineIn[left][2] + lineIn[right][2]) * fw; \
bulk[3] = (acc[3] * ww) + (lineIn[left][3] + lineIn[right][3]) * fw;
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#define SAVE(x, bulk) \
lineOut[x][0] = (UINT8)((bulk[0] + (1 << 23)) >> 24); \
lineOut[x][1] = (UINT8)((bulk[1] + (1 << 23)) >> 24); \
lineOut[x][2] = (UINT8)((bulk[2] + (1 << 23)) >> 24); \
lineOut[x][3] = (UINT8)((bulk[3] + (1 << 23)) >> 24);
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/* Compute acc for -1 pixel (outside of image):
From "-radius-1" to "-1" get first pixel,
then from "0" to "radius-1". */
acc[0] = lineIn[0][0] * (radius + 1);
acc[1] = lineIn[0][1] * (radius + 1);
acc[2] = lineIn[0][2] * (radius + 1);
acc[3] = lineIn[0][3] * (radius + 1);
/* As radius can be bigger than xsize, iterate to edgeA -1. */
for (x = 0; x < edgeA - 1; x++) {
acc[0] += lineIn[x][0];
acc[1] += lineIn[x][1];
acc[2] += lineIn[x][2];
acc[3] += lineIn[x][3];
}
/* Then multiply remainder to last x. */
acc[0] += lineIn[lastx][0] * (radius - edgeA + 1);
acc[1] += lineIn[lastx][1] * (radius - edgeA + 1);
acc[2] += lineIn[lastx][2] * (radius - edgeA + 1);
acc[3] += lineIn[lastx][3] * (radius - edgeA + 1);
if (edgeA <= edgeB)
{
/* Subtract pixel from left ("0").
Add pixels from radius. */
for (x = 0; x < edgeA; x++) {
MOVE_ACC(acc, 0, x + radius);
ADD_FAR(bulk, acc, 0, x + radius + 1);
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SAVE(x, bulk);
}
/* Subtract previous pixel from "-radius".
Add pixels from radius. */
for (x = edgeA; x < edgeB; x++) {
MOVE_ACC(acc, x - radius - 1, x + radius);
ADD_FAR(bulk, acc, x - radius - 1, x + radius + 1);
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SAVE(x, bulk);
}
/* Subtract previous pixel from "-radius".
Add last pixel. */
for (x = edgeB; x <= lastx; x++) {
MOVE_ACC(acc, x - radius - 1, lastx);
ADD_FAR(bulk, acc, x - radius - 1, lastx);
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SAVE(x, bulk);
}
}
else
{
for (x = 0; x < edgeB; x++) {
MOVE_ACC(acc, 0, x + radius);
ADD_FAR(bulk, acc, 0, x + radius + 1);
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SAVE(x, bulk);
}
for (x = edgeB; x < edgeA; x++) {
MOVE_ACC(acc, 0, lastx);
ADD_FAR(bulk, acc, 0, lastx);
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SAVE(x, bulk);
}
for (x = edgeA; x <= lastx; x++) {
MOVE_ACC(acc, x - radius - 1, lastx);
ADD_FAR(bulk, acc, x - radius - 1, lastx);
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SAVE(x, bulk);
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}
}
#undef MOVE_ACC
#undef ADD_FAR
#undef SAVE
}
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void static inline
ImagingLineBoxBlur8(UINT8 *lineOut, UINT8 *lineIn, int lastx, int radius, int edgeA,
int edgeB, UINT32 ww, UINT32 fw)
{
int x;
UINT32 acc;
UINT32 bulk;
#define MOVE_ACC(acc, subtract, add) \
acc += lineIn[add] - lineIn[subtract];
#define ADD_FAR(bulk, acc, left, right) \
bulk = (acc * ww) + (lineIn[left] + lineIn[right]) * fw;
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#define SAVE(x, bulk) \
lineOut[x] = (UINT8)((bulk + (1 << 23)) >> 24)
acc = lineIn[0] * (radius + 1);
for (x = 0; x < edgeA - 1; x++) {
acc += lineIn[x];
}
acc += lineIn[lastx] * (radius - edgeA + 1);
if (edgeA <= edgeB)
{
for (x = 0; x < edgeA; x++) {
MOVE_ACC(acc, 0, x + radius);
ADD_FAR(bulk, acc, 0, x + radius + 1);
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SAVE(x, bulk);
}
for (x = edgeA; x < edgeB; x++) {
MOVE_ACC(acc, x - radius - 1, x + radius);
ADD_FAR(bulk, acc, x - radius - 1, x + radius + 1);
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SAVE(x, bulk);
}
for (x = edgeB; x <= lastx; x++) {
MOVE_ACC(acc, x - radius - 1, lastx);
ADD_FAR(bulk, acc, x - radius - 1, lastx);
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SAVE(x, bulk);
}
}
else
{
for (x = 0; x < edgeB; x++) {
MOVE_ACC(acc, 0, x + radius);
ADD_FAR(bulk, acc, 0, x + radius + 1);
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SAVE(x, bulk);
}
for (x = edgeB; x < edgeA; x++) {
MOVE_ACC(acc, 0, lastx);
ADD_FAR(bulk, acc, 0, lastx);
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SAVE(x, bulk);
}
for (x = edgeA; x <= lastx; x++) {
MOVE_ACC(acc, x - radius - 1, lastx);
ADD_FAR(bulk, acc, x - radius - 1, lastx);
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SAVE(x, bulk);
}
}
#undef MOVE_ACC
#undef ADD_FAR
#undef SAVE
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}
Imaging
ImagingHorizontalBoxBlur(Imaging imOut, Imaging imIn, float floatRadius)
{
ImagingSectionCookie cookie;
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int y;
int radius = (int) floatRadius;
UINT32 ww = (UINT32) (1 << 24) / (floatRadius * 2 + 1);
UINT32 fw = ((1 << 24) - (radius * 2 + 1) * ww) / 2;
int edgeA = MIN(radius + 1, imIn->xsize);
int edgeB = MAX(imIn->xsize - radius - 1, 0);
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UINT32 *lineOut = calloc(imIn->xsize, sizeof(UINT32));
if (lineOut == NULL)
return ImagingError_MemoryError();
// printf(">>> %d %d %d\n", radius, ww, fw);
ImagingSectionEnter(&cookie);
if (imIn->image8)
{
for (y = 0; y < imIn->ysize; y++) {
ImagingLineBoxBlur8(
(imIn == imOut ? (UINT8 *) lineOut : imOut->image8[y]),
imIn->image8[y],
imIn->xsize - 1,
radius, edgeA, edgeB,
ww, fw
);
if (imIn == imOut) {
// Commit.
memcpy(imOut->image8[y], lineOut, imIn->xsize);
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}
}
}
else
{
for (y = 0; y < imIn->ysize; y++) {
ImagingLineBoxBlur32(
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imIn == imOut ? (pixel *) lineOut : (pixel *) imOut->image32[y],
(pixel *) imIn->image32[y],
imIn->xsize - 1,
radius, edgeA, edgeB,
ww, fw
);
if (imIn == imOut) {
// Commit.
memcpy(imOut->image32[y], lineOut, imIn->xsize * 4);
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}
}
}
ImagingSectionLeave(&cookie);
free(lineOut);
return imOut;
}
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Imaging
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ImagingBoxBlur(Imaging imOut, Imaging imIn, float radius, int n)
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{
int i;
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Imaging imTransposed;
if (n < 1) {
return ImagingError_ValueError(
"number of passes must be greater than zero"
);
}
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if (strcmp(imIn->mode, imOut->mode) ||
imIn->type != imOut->type ||
imIn->bands != imOut->bands ||
imIn->xsize != imOut->xsize ||
imIn->ysize != imOut->ysize)
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return ImagingError_Mismatch();
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if (imIn->type != IMAGING_TYPE_UINT8)
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return ImagingError_ModeError();
if (!(strcmp(imIn->mode, "RGB") == 0 ||
strcmp(imIn->mode, "RGBA") == 0 ||
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strcmp(imIn->mode, "RGBa") == 0 ||
strcmp(imIn->mode, "RGBX") == 0 ||
strcmp(imIn->mode, "CMYK") == 0 ||
strcmp(imIn->mode, "L") == 0 ||
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strcmp(imIn->mode, "LA") == 0 ||
strcmp(imIn->mode, "La") == 0))
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return ImagingError_ModeError();
imTransposed = ImagingNewDirty(imIn->mode, imIn->ysize, imIn->xsize);
if (!imTransposed)
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return NULL;
/* Apply blur in one dimension.
Use imOut as a destination at first pass,
then use imOut as a source too. */
ImagingHorizontalBoxBlur(imOut, imIn, radius);
for (i = 1; i < n; i ++) {
ImagingHorizontalBoxBlur(imOut, imOut, radius);
}
/* Transpose result for blur in another direction. */
ImagingTranspose(imTransposed, imOut);
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/* Reuse imTransposed as a source and destination there. */
for (i = 0; i < n; i ++) {
ImagingHorizontalBoxBlur(imTransposed, imTransposed, radius);
}
/* Restore original orientation. */
ImagingTranspose(imOut, imTransposed);
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ImagingDelete(imTransposed);
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return imOut;
}
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Imaging ImagingGaussianBlur(Imaging imOut, Imaging imIn, float radius,
int passes)
{
float sigma2, L, l, a;
sigma2 = radius * radius / passes;
// from http://www.mia.uni-saarland.de/Publications/gwosdek-ssvm11.pdf
// [7] Box length.
L = sqrt(12.0 * sigma2 + 1.0);
// [11] Integer part of box radius.
l = floor((L - 1.0) / 2.0);
// [14], [Fig. 2] Fractional part of box radius.
a = (2 * l + 1) * (l * (l + 1) - 3 * sigma2);
a /= 6 * (sigma2 - (l + 1) * (l + 1));
return ImagingBoxBlur(imOut, imIn, l + a, passes);
}