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Speed up Image.fill(), Image.linear_gradient() and Image.radial_gradient(). #9737

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Merged
hugovk merged 4 commits into from
Jul 1, 2026
+67 −37
Merged

Speed up Image.fill(), Image.linear_gradient() and Image.radial_gradient(). #9737

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2bc8e5c
Fill: hoist static sizes out of loop; restrict row pointer
akx Jun 2, 2026
93a2649
Add benchmarks for linear_gradient and radial_gradient
akx Jun 30, 2026
6368935
Apply hoists and restricts in `Image.*_gradient()``
akx Jun 30, 2026
f7f350a
De-triplicate `Image.*_gradient()`'s loops with a macro
akx Jun 30, 2026
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16 changes: 16 additions & 0 deletions Tests/benchmarks.py
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Original file line number Diff line number Diff line change
Expand Up @@ -354,6 +354,22 @@ def test_fill(bench: BenchmarkFixture, mode: str, size: tuple[int, int]) -> None
bench(Image.new, mode, size, color)


@pytest.mark.benchmark(group="allocate")
@pytest.mark.parametrize("mode", ["1", "F", "I", "L", "P"])
def test_linear_gradient(bench: BenchmarkFixture, mode: str) -> None:
result = bench(Image.linear_gradient, mode)
assert result.size == (256, 256)
assert result.mode == mode


@pytest.mark.benchmark(group="allocate")
@pytest.mark.parametrize("mode", ["1", "F", "I", "L", "P"])
def test_radial_gradient(bench: BenchmarkFixture, mode: str) -> None:
result = bench(Image.radial_gradient, mode)
assert result.size == (256, 256)
assert result.mode == mode


CHOPS_OPS = [
ImageChops.add,
ImageChops.subtract,
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88 changes: 51 additions & 37 deletions src/libImaging/Fill.c
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Original file line number Diff line number Diff line change
Expand Up @@ -21,27 +21,30 @@

Imaging
ImagingFill(Imaging im, const void *colour) {
int x, y;
ImagingSectionCookie cookie;

/* 0-width or 0-height image. No need to do anything */
if (!im->linesize || !im->ysize) {
return im;
}

// xsize and ysize are invariant during the loops below.
int xsize = im->xsize;
int ysize = im->ysize;

if (im->type == IMAGING_TYPE_SPECIAL) {
/* use generic API */
ImagingAccess access = ImagingAccessNew(im);
if (access) {
for (y = 0; y < im->ysize; y++) {
for (x = 0; x < im->xsize; x++) {
for (int y = 0; y < ysize; y++) {
for (int x = 0; x < xsize; x++) {
access->put_pixel(im, x, y, colour);
}
}
ImagingAccessDelete(im, access);
} else {
/* wipe the image */
for (y = 0; y < im->ysize; y++) {
for (int y = 0; y < ysize; y++) {
memset(im->image[y], 0, im->linesize);
}
}
Expand All @@ -50,14 +53,16 @@ ImagingFill(Imaging im, const void *colour) {
ImagingSectionEnter(&cookie);
memcpy(&c, colour, im->pixelsize);
if (im->image32 && c != 0L) {
for (y = 0; y < im->ysize; y++) {
for (x = 0; x < im->xsize; x++) {
im->image32[y][x] = c;
for (int y = 0; y < ysize; y++) {
// Restrict safe: sole owner of image data here.
INT32 *restrict row = im->image32[y];
for (int x = 0; x < xsize; x++) {
row[x] = c;
}
}
} else {
unsigned char cc = (unsigned char)*(UINT8 *)colour;
for (y = 0; y < im->ysize; y++) {
for (int y = 0; y < ysize; y++) {
memset(im->image[y], cc, im->linesize);
}
}
Expand All @@ -70,7 +75,6 @@ ImagingFill(Imaging im, const void *colour) {
Imaging
ImagingFillLinearGradient(const ModeID mode) {
Imaging im;
int y;

if (mode != IMAGING_MODE_1 && mode != IMAGING_MODE_F && mode != IMAGING_MODE_I &&
mode != IMAGING_MODE_L && mode != IMAGING_MODE_P) {
Expand All @@ -82,19 +86,24 @@ ImagingFillLinearGradient(const ModeID mode) {
return NULL;
}

// Branch on pixel type outside the loops so the compiler can tighten them.
// Restrict safe: sole owner of the freshly-allocated image data here.
if (im->image8) {
for (y = 0; y < 256; y++) {
for (int y = 0; y < 256; y++) {
memset(im->image8[y], (unsigned char)y, 256);
}
} else if (im->type == IMAGING_TYPE_FLOAT32) {
for (int y = 0; y < 256; y++) {
FLOAT32 *restrict row = (FLOAT32 *)im->image32[y];
for (int x = 0; x < 256; x++) {
row[x] = y;
}
}
} else {
int x;
for (y = 0; y < 256; y++) {
for (x = 0; x < 256; x++) {
if (im->type == IMAGING_TYPE_FLOAT32) {
IMAGING_PIXEL_FLOAT32(im, x, y) = y;
} else {
IMAGING_PIXEL_INT32(im, x, y) = y;
}
for (int y = 0; y < 256; y++) {
INT32 *restrict row = im->image32[y];
for (int x = 0; x < 256; x++) {
row[x] = y;
}
}
}
Expand All @@ -105,8 +114,6 @@ ImagingFillLinearGradient(const ModeID mode) {
Imaging
ImagingFillRadialGradient(const ModeID mode) {
Imaging im;
int x, y;
int d;

if (mode != IMAGING_MODE_1 && mode != IMAGING_MODE_F && mode != IMAGING_MODE_I &&
mode != IMAGING_MODE_L && mode != IMAGING_MODE_P) {
Expand All @@ -118,25 +125,32 @@ ImagingFillRadialGradient(const ModeID mode) {
return NULL;
}

for (y = 0; y < 256; y++) {
for (x = 0; x < 256; x++) {
d = (int)sqrt(
(double)((x - 128) * (x - 128) + (y - 128) * (y - 128)) * 2.0
);
if (d >= 255) {
d = 255;
}
if (im->image8) {
im->image8[y][x] = d;
} else {
if (im->type == IMAGING_TYPE_FLOAT32) {
IMAGING_PIXEL_FLOAT32(im, x, y) = d;
} else {
IMAGING_PIXEL_INT32(im, x, y) = d;
}
}
#define ASSIGN_ROW(row, y) \
for (int x = 0; x < 256; x++) { \
int d = \
(int)sqrt((double)((x - 128) * (x - 128) + (y - 128) * (y - 128)) * 2.0); \
row[x] = d >= 255 ? 255 : d; \
}

// Branch on pixel type outside the loops so the compiler can tighten them.
// Restrict safe: sole owner of the freshly-allocated image data here.
if (im->image8) {
for (int y = 0; y < 256; y++) {
UINT8 *restrict row = im->image8[y];
ASSIGN_ROW(row, y);
}
} else if (im->type == IMAGING_TYPE_FLOAT32) {
for (int y = 0; y < 256; y++) {
FLOAT32 *restrict row = (FLOAT32 *)im->image32[y];
ASSIGN_ROW(row, y);
}
} else {
for (int y = 0; y < 256; y++) {
INT32 *restrict row = im->image32[y];
ASSIGN_ROW(row, y);
}
}
#undef ASSIGN_ROW

return im;
}
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