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Merge pull request #2091 from wiredfool/pr_2008

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Resampling lookups, trailing empty coefficients, precision
This commit is contained in:
wiredfool 2016-08-25 12:58:36 +01:00 committed by GitHub
commit 39227ff33c
2 changed files with 107 additions and 34 deletions
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17
Tests/test_image_resample.py
View File

@ -320,5 +320,22 @@ class CoreResamplePassesTest(PillowTestCase):
self.assertEqual(Image.core.getcount(), count + 2)
class CoreResampleCoefficientsTest(PillowTestCase):
def test_reduce(self):
test_color = 254
# print ''
for size in range(400000, 400010, 2):
# print '\r', size,
i = Image.new('L', (size, 1), 0)
draw = ImageDraw.Draw(i)
draw.rectangle((0, 0, i.size[0] // 2 - 1, 0), test_color)
px = i.resize((5, i.size[1]), Image.BICUBIC).load()
if px[2, 0] != test_color // 2:
self.assertEqual(test_color // 2, px[2, 0])
# print '\r>', size, test_color // 2, px[2, 0]
if __name__ == '__main__':
unittest.main()

124
libImaging/Resample.c
View File

@ -80,18 +80,52 @@ static struct filter LANCZOS = { lanczos_filter, 3.0 };
#define PRECISION_BITS (32 - 8 - 2)
UINT8 _lookups[512] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63,
64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79,
80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127,
128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143,
144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175,
176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191,
192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 206, 207,
208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223,
224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239,
240, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255
};
UINT8 *lookups = &_lookups[128];
static inline UINT8 clip8(int in)
{
if (in >= (1 << PRECISION_BITS << 8))
return 255;
if (in <= 0)
return 0;
return (UINT8) (in >> PRECISION_BITS);
return lookups[in >> PRECISION_BITS];
}
int
ImagingPrecompute(int inSize, int outSize, struct filter *filterp,
precompute_coeffs(int inSize, int outSize, struct filter *filterp,
int **xboundsp, double **kkp) {
double support, scale, filterscale;
double center, ww, ss;
@ -142,6 +176,16 @@ ImagingPrecompute(int inSize, int outSize, struct filter *filterp,
k = &kk[xx * kmax];
for (x = 0; x < xmax; x++) {
double w = filterp->filter((x + xmin - center + 0.5) * ss);
if (w == 0) {
if (x == 0) {
x -= 1;
xmin += 1;
xmax -= 1;
} else if (x == xmax - 1) {
xmax -= 1;
}
continue;
}
k[x] = w;
ww += w;
}
@ -162,6 +206,32 @@ ImagingPrecompute(int inSize, int outSize, struct filter *filterp,
}
int
normalize_coeffs_8bpc(int outSize, int kmax, double *prekk, INT32 **kkp)
{
int x;
INT32 *kk;
/* malloc check ok, overflow checked in precompute_coeffs */
kk = malloc(outSize * kmax * sizeof(INT32));
if ( ! kk) {
return 0;
}
for (x = 0; x < outSize * kmax; x++) {
if (prekk[x] < 0) {
kk[x] = (int) (-0.5 + prekk[x] * (1 << PRECISION_BITS));
} else {
kk[x] = (int) (0.5 + prekk[x] * (1 << PRECISION_BITS));
}
}
*kkp = kk;
return kmax;
}
Imaging
ImagingResampleHorizontal_8bpc(Imaging imIn, int xsize, struct filter *filterp)
{
@ -170,28 +240,21 @@ ImagingResampleHorizontal_8bpc(Imaging imIn, int xsize, struct filter *filterp)
int ss0, ss1, ss2, ss3;
int xx, yy, x, kmax, xmin, xmax;
int *xbounds;
int *k, *kk;
INT32 *k, *kk;
double *prekk;
kmax = ImagingPrecompute(imIn->xsize, xsize, filterp, &xbounds, &prekk);
kmax = precompute_coeffs(imIn->xsize, xsize, filterp, &xbounds, &prekk);
if ( ! kmax) {
return (Imaging) ImagingError_MemoryError();
}
kk = malloc(xsize * kmax * sizeof(int));
if ( ! kk) {
kmax = normalize_coeffs_8bpc(xsize, kmax, prekk, &kk);
free(prekk);
if ( ! kmax) {
free(xbounds);
free(prekk);
return (Imaging) ImagingError_MemoryError();
}
for (x = 0; x < xsize * kmax; x++) {
kk[x] = (int) (0.5 + prekk[x] * (1 << PRECISION_BITS));
}
free(prekk);
imOut = ImagingNew(imIn->mode, xsize, imIn->ysize);
if ( ! imOut) {
free(kk);
@ -282,28 +345,21 @@ ImagingResampleVertical_8bpc(Imaging imIn, int ysize, struct filter *filterp)
int ss0, ss1, ss2, ss3;
int xx, yy, y, kmax, ymin, ymax;
int *xbounds;
int *k, *kk;
INT32 *k, *kk;
double *prekk;
kmax = ImagingPrecompute(imIn->ysize, ysize, filterp, &xbounds, &prekk);
kmax = precompute_coeffs(imIn->ysize, ysize, filterp, &xbounds, &prekk);
if ( ! kmax) {
return (Imaging) ImagingError_MemoryError();
}
kk = malloc(ysize * kmax * sizeof(int));
if ( ! kk) {
kmax = normalize_coeffs_8bpc(ysize, kmax, prekk, &kk);
free(prekk);
if ( ! kmax) {
free(xbounds);
free(prekk);
return (Imaging) ImagingError_MemoryError();
}
for (y = 0; y < ysize * kmax; y++) {
kk[y] = (int) (0.5 + prekk[y] * (1 << PRECISION_BITS));
}
free(prekk);
imOut = ImagingNew(imIn->mode, imIn->xsize, ysize);
if ( ! imOut) {
free(kk);
@ -396,7 +452,7 @@ ImagingResampleHorizontal_32bpc(Imaging imIn, int xsize, struct filter *filterp)
int *xbounds;
double *k, *kk;
kmax = ImagingPrecompute(imIn->xsize, xsize, filterp, &xbounds, &kk);
kmax = precompute_coeffs(imIn->xsize, xsize, filterp, &xbounds, &kk);
if ( ! kmax) {
return (Imaging) ImagingError_MemoryError();
}
@ -456,7 +512,7 @@ ImagingResampleVertical_32bpc(Imaging imIn, int ysize, struct filter *filterp)
int *xbounds;
double *k, *kk;
kmax = ImagingPrecompute(imIn->ysize, ysize, filterp, &xbounds, &kk);
kmax = precompute_coeffs(imIn->ysize, ysize, filterp, &xbounds, &kk);
if ( ! kmax) {
return (Imaging) ImagingError_MemoryError();
}