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Gaussian blur radius fix #2246

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Merged
MyreMylar merged 6 commits into from
Jun 25, 2023
Merged

Gaussian blur radius fix #2246

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bf21c90
remove unnecessary factors
yunline Jun 13, 2023
23f29fa
fix #2239
yunline Jun 13, 2023
f3b52c2
update naming
yunline Jun 13, 2023
53b7974
update test
yunline Jun 13, 2023
a241027
update docs
yunline Jun 13, 2023
4e671ec
2.3.0 -> 2.3.1
yunline Jun 18, 2023
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4 changes: 4 additions & 0 deletions docs/reST/ref/transform.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -262,6 +262,10 @@ Instead, always begin with the original image and scale to the desired size.)

.. versionchanged:: 2.3.0
Passing the calling surface as destination surface raises a ``ValueError``

.. versionchanged:: 2.3.1
Now the standard deviation of the Gaussian kernel is equal to the radius.
Blur results will be slightly different.

.. ## pygame.transform.gaussian_blur ##

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21 changes: 10 additions & 11 deletions src_c/transform.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3060,7 +3060,7 @@ box_blur(SDL_Surface *src, SDL_Surface *dst, int radius, SDL_bool repeat)
}

static void
gaussian_blur(SDL_Surface *src, SDL_Surface *dst, int radius, SDL_bool repeat)
gaussian_blur(SDL_Surface *src, SDL_Surface *dst, int sigma, SDL_bool repeat)
{
Uint8 *srcpx = (Uint8 *)src->pixels;
Uint8 *dstpx = (Uint8 *)dst->pixels;
Expand All @@ -3069,21 +3069,20 @@ gaussian_blur(SDL_Surface *src, SDL_Surface *dst, int radius, SDL_bool repeat)
int dst_pitch = dst->pitch;
int src_pitch = src->pitch;
int i, j, x, y, color;
int kernel_radius = sigma * 2;
float *buf = malloc(dst_pitch * sizeof(float));
float *buf2 = malloc(dst_pitch * sizeof(float));
float *lut = malloc((radius + 1) * sizeof(float));
float *lut = malloc((kernel_radius + 1) * sizeof(float));
float lut_sum = 0.0;

for (i = 0; i <= radius; i++) { // init gaussian lut
// Gaussian function, radius=2*sigma
lut[i] = (float)radius / 2.0f *
expf(-powf((float)i, 2.0f) /
(2.0f * powf((float)radius / 2.0f, 2.0f))) *
0.3989422804014327f;
for (i = 0; i <= kernel_radius; i++) { // init gaussian lut
// Gaussian function
lut[i] =
expf(-powf((float)i, 2.0f) / (2.0f * powf((float)sigma, 2.0f)));
lut_sum += lut[i] * 2;
}
lut_sum -= lut[0];
for (i = 0; i <= radius; i++) {
for (i = 0; i <= kernel_radius; i++) {
lut[i] /= lut_sum;
}

Expand All @@ -3093,7 +3092,7 @@ gaussian_blur(SDL_Surface *src, SDL_Surface *dst, int radius, SDL_bool repeat)
}

for (y = 0; y < h; y++) {
for (j = -radius; j <= radius; j++) {
for (j = -kernel_radius; j <= kernel_radius; j++) {
for (i = 0; i < dst_pitch; i++) {
if (y + j >= 0 && y + j < h) {
buf[i] +=
Expand All @@ -3112,7 +3111,7 @@ gaussian_blur(SDL_Surface *src, SDL_Surface *dst, int radius, SDL_bool repeat)
}

for (x = 0; x < w; x++) {
for (j = -radius; j <= radius; j++) {
for (j = -kernel_radius; j <= kernel_radius; j++) {
for (color = 0; color < nb; color++) {
if (x + j >= 0 && x + j < w) {
buf2[nb * x + color] +=
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56 changes: 28 additions & 28 deletions test/transform_test.py
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Expand Up @@ -1502,36 +1502,36 @@ def test_box_blur(self):

def test_gaussian_blur(self):
data1 = {
(10, 49): (109, 107, 48, 255),
(47, 66): (134, 138, 66, 255),
(84, 103): (139, 74, 47, 255),
(121, 140): (152, 129, 69, 255),
(148, 177): (162, 185, 91, 255),
(195, 214): (167, 125, 62, 255),
(232, 21): (153, 51, 36, 255),
(269, 288): (120, 163, 95, 255),
(306, 325): (115, 160, 92, 255),
(343, 362): (109, 145, 66, 255),
(384, 379): (112, 146, 71, 255),
(417, 436): (123, 83, 48, 255),
(454, 473): (170, 94, 74, 255),
(491, 510): (75, 42, 33, 255),
(10, 49): (74, 67, 32, 255),
(47, 66): (112, 93, 47, 255),
(84, 103): (141, 104, 57, 255),
(121, 140): (153, 118, 64, 255),
(148, 177): (161, 140, 73, 255),
(195, 214): (162, 137, 72, 255),
(232, 21): (124, 50, 35, 255),
(269, 288): (123, 146, 83, 255),
(306, 325): (118, 154, 85, 255),
(343, 362): (114, 141, 73, 255),
(384, 379): (114, 116, 61, 255),
(417, 436): (121, 78, 47, 255),
(454, 473): (107, 54, 39, 255),
(491, 510): (57, 28, 22, 255),
}
data2 = {
(10, 49): (109, 107, 48, 255),
(47, 66): (134, 138, 66, 255),
(84, 103): (139, 74, 47, 255),
(121, 140): (152, 129, 69, 255),
(148, 177): (162, 185, 91, 255),
(195, 214): (167, 125, 62, 255),
(232, 21): (153, 51, 36, 255),
(269, 288): (120, 163, 95, 255),
(306, 325): (115, 160, 92, 255),
(343, 362): (109, 145, 66, 255),
(384, 379): (112, 146, 71, 255),
(417, 436): (123, 83, 48, 255),
(454, 473): (170, 94, 74, 255),
(491, 510): (75, 42, 33, 255),
(10, 49): (74, 67, 32, 255),
(47, 66): (112, 93, 47, 255),
(84, 103): (141, 104, 57, 255),
(121, 140): (153, 118, 64, 255),
(148, 177): (161, 140, 73, 255),
(195, 214): (162, 137, 72, 255),
(232, 21): (124, 50, 35, 255),
(269, 288): (123, 146, 83, 255),
(306, 325): (118, 154, 85, 255),
(343, 362): (114, 141, 73, 255),
(384, 379): (114, 116, 61, 255),
(417, 436): (121, 78, 47, 255),
(454, 473): (107, 54, 39, 255),
(491, 510): (57, 28, 22, 255),
}

data_fname = example_path("data")
Expand Down