Merge pull request #2676 from uploadcare/fast-split

Fast split()

PIL/Image.py

@@ -1958,9 +1958,7 @@ class Image(object):
         if self.im.bands == 1:
             ims = [self.copy()]
         else:
-            ims = []
+            ims = map(self._new, self.im.split())
-            for i in range(self.im.bands):
-                ims.append(self._new(self.im.getband(i)))
         return tuple(ims)
 
     def getchannel(self, channel):

_imaging.c

@@ -1888,6 +1888,32 @@ _putband(ImagingObject* self, PyObject* args)
     return Py_None;
 }
 
+static PyObject*
+_split(ImagingObject* self, PyObject* args)
+{
+    int fails = 0;
+    Py_ssize_t i;
+    PyObject* list;
+    PyObject* imaging_object;
+    Imaging bands[4] = {NULL, NULL, NULL, NULL};
+
+    if ( ! ImagingSplit(self->image, bands))
+        return NULL;
+
+    list = PyTuple_New(self->image->bands);
+    for (i = 0; i < self->image->bands; i++) {
+        imaging_object = PyImagingNew(bands[i]);
+        if ( ! imaging_object)
+            fails += 1;
+        PyTuple_SET_ITEM(list, i, imaging_object);
+    }
+    if (fails) {
+        Py_DECREF(list);
+        list = NULL;
+    }
+    return list;
+}
+
 /* -------------------------------------------------------------------- */
 
 #ifdef WITH_IMAGECHOPS
@@ -2954,6 +2980,7 @@ static struct PyMethodDef methods[] = {
 
     {"getband", (PyCFunction)_getband, 1},
     {"putband", (PyCFunction)_putband, 1},
+    {"split", (PyCFunction)_split, 1},
     {"fillband", (PyCFunction)_fillband, 1},
 
     {"setmode", (PyCFunction)im_setmode, 1},

libImaging/Bands.c

@@ -22,6 +22,13 @@
 #define CLIP(x) ((x) <= 0 ? 0 : (x) < 256 ? (x) : 255)
 
 
+#ifdef WORDS_BIGENDIAN
+    #define MAKE_UINT32(u0, u1, u2, u3) (u3 | (u2<<8)  | (u1<<16)  | (u0<<24))
+#else
+    #define MAKE_UINT32(u0, u1, u2, u3) (u0 | (u1<<8)  | (u2<<16)  | (u3<<24))
+#endif
+
+
 Imaging
 ImagingGetBand(Imaging imIn, int band)
 {
@@ -51,7 +58,12 @@ ImagingGetBand(Imaging imIn, int band)
     for (y = 0; y < imIn->ysize; y++) {
         UINT8* in = (UINT8*) imIn->image[y] + band;
         UINT8* out = imOut->image8[y];
-        for (x = 0; x < imIn->xsize; x++) {
+        x = 0;
+        for (; x < imIn->xsize - 3; x += 4) {
+            *((UINT32*) (out + x)) = MAKE_UINT32(in[0], in[4], in[8], in[12]);
+            in += 16;
+        }
+        for (; x < imIn->xsize; x++) {
             out[x] = *in;
             in += 4;
         }
@@ -60,6 +72,101 @@ ImagingGetBand(Imaging imIn, int band)
     return imOut;
 }
 
+
+int
+ImagingSplit(Imaging imIn, Imaging bands[4])
+{
+    int i, j, x, y;
+
+    /* Check arguments */
+    if (!imIn || imIn->type != IMAGING_TYPE_UINT8) {
+        (Imaging) ImagingError_ModeError();
+        return 0;
+    }
+
+    /* Shortcuts */
+    if (imIn->bands == 1) {
+        bands[0] = ImagingCopy(imIn);
+        return imIn->bands;
+    }
+
+    for (i = 0; i < imIn->bands; i++) {
+        bands[i] = ImagingNew("L", imIn->xsize, imIn->ysize);
+        if ( ! bands[i]) {
+            for (j = 0; j < i; ++j) {
+                ImagingDelete(bands[j]);
+            }
+            return 0;
+        }
+    }
+
+    /* Extract bands from image */
+    if (imIn->bands == 2) {
+        for (y = 0; y < imIn->ysize; y++) {
+            UINT8* in = (UINT8*) imIn->image[y];
+            UINT8* out0 = bands[0]->image8[y];
+            UINT8* out1 = bands[1]->image8[y];
+            x = 0;
+            for (; x < imIn->xsize - 3; x += 4) {
+                *((UINT32*) (out0 + x)) = MAKE_UINT32(in[0], in[4], in[8], in[12]);
+                *((UINT32*) (out1 + x)) = MAKE_UINT32(in[0+3], in[4+3], in[8+3], in[12+3]);
+                in += 16;
+            }
+            for (; x < imIn->xsize; x++) {
+                out0[x] = in[0];
+                out1[x] = in[3];
+                in += 4;
+            }
+        }
+    } else if (imIn->bands == 3) {
+        for (y = 0; y < imIn->ysize; y++) {
+            UINT8* in = (UINT8*) imIn->image[y];
+            UINT8* out0 = bands[0]->image8[y];
+            UINT8* out1 = bands[1]->image8[y];
+            UINT8* out2 = bands[2]->image8[y];
+            x = 0;
+            for (; x < imIn->xsize - 3; x += 4) {
+                *((UINT32*) (out0 + x)) = MAKE_UINT32(in[0], in[4], in[8], in[12]);
+                *((UINT32*) (out1 + x)) = MAKE_UINT32(in[0+1], in[4+1], in[8+1], in[12+1]);
+                *((UINT32*) (out2 + x)) = MAKE_UINT32(in[0+2], in[4+2], in[8+2], in[12+2]);
+                in += 16;
+            }
+            for (; x < imIn->xsize; x++) {
+                out0[x] = in[0];
+                out1[x] = in[1];
+                out2[x] = in[2];
+                in += 4;
+            }
+        }
+    } else {
+        for (y = 0; y < imIn->ysize; y++) {
+            UINT8* in = (UINT8*) imIn->image[y];
+            UINT8* out0 = bands[0]->image8[y];
+            UINT8* out1 = bands[1]->image8[y];
+            UINT8* out2 = bands[2]->image8[y];
+            UINT8* out3 = bands[3]->image8[y];
+            x = 0;
+            for (; x < imIn->xsize - 3; x += 4) {
+                *((UINT32*) (out0 + x)) = MAKE_UINT32(in[0], in[4], in[8], in[12]);
+                *((UINT32*) (out1 + x)) = MAKE_UINT32(in[0+1], in[4+1], in[8+1], in[12+1]);
+                *((UINT32*) (out2 + x)) = MAKE_UINT32(in[0+2], in[4+2], in[8+2], in[12+2]);
+                *((UINT32*) (out3 + x)) = MAKE_UINT32(in[0+3], in[4+3], in[8+3], in[12+3]);
+                in += 16;
+            }
+            for (; x < imIn->xsize; x++) {
+                out0[x] = in[0];
+                out1[x] = in[1];
+                out2[x] = in[2];
+                out3[x] = in[3];
+                in += 4;
+            }
+        }
+    }
+
+    return imIn->bands;
+}
+
+
 Imaging
 ImagingPutBand(Imaging imOut, Imaging imIn, int band)
 {

libImaging/Imaging.h

@@ -266,6 +266,7 @@ extern Imaging ImagingFlipTopBottom(Imaging imOut, Imaging imIn);
 extern Imaging ImagingGaussianBlur(Imaging imOut, Imaging imIn, float radius,
     int passes);
 extern Imaging ImagingGetBand(Imaging im, int band);
+extern int ImagingSplit(Imaging im, Imaging bands[4]);
 extern int ImagingGetBBox(Imaging im, int bbox[4]);
 typedef struct { int x, y; INT32 count; INT32 pixel; } ImagingColorItem;
 extern ImagingColorItem* ImagingGetColors(Imaging im, int maxcolors,