get and set BGR pixels as BGR without scaling

Tests/test_image_access.py

@@ -137,10 +137,6 @@ def color(mode: str) -> int | tuple[int, ...]:
         bands = Image.getmodebands(mode)
         if bands == 1:
             return 1
-        if mode in ("BGR;15", "BGR;16"):
-            # These modes have less than 8 bits per band
-            # So (1, 2, 3) cannot be roundtripped
-            return (16, 32, 49)
         return tuple(range(1, bands + 1))
 
     def check(self, mode: str, expected_color_int: int | None = None) -> None:

Tests/test_image_putdata.py

@@ -80,7 +80,7 @@ def test_mode_F() -> None:
 
 @pytest.mark.parametrize("mode", ("BGR;15", "BGR;16", "BGR;24"))
 def test_mode_BGR(mode: str) -> None:
-    data = [(16, 32, 49), (32, 32, 98)]
+    data = [(1, 2, 3), (10, 11, 12)]
     im = Image.new(mode, (1, 2))
     im.putdata(data)
 

Tests/test_lib_pack.py

@@ -359,10 +359,8 @@ def test_RGB(self) -> None:
         )
 
     def test_BGR(self) -> None:
-        self.assert_unpack("BGR;15", "BGR;15", 3, (8, 131, 0), (24, 0, 8), (41, 131, 8))
-        self.assert_unpack(
-            "BGR;16", "BGR;16", 3, (8, 64, 0), (24, 129, 0), (41, 194, 0)
-        )
+        self.assert_unpack("BGR;15", "BGR;15", 3, (0, 16, 1), (1, 0, 3), (1, 16, 5))
+        self.assert_unpack("BGR;16", "BGR;16", 3, (0, 16, 1), (0, 32, 3), (0, 48, 5))
         self.assert_unpack("BGR;24", "BGR;24", 3, (1, 2, 3), (4, 5, 6), (7, 8, 9))
 
     def test_RGBA(self) -> None:

src/_imaging.c

@@ -605,18 +605,18 @@ getink(PyObject *color, Imaging im, char *ink) {
                     return NULL;
                 }
                 if (!strcmp(im->mode, "BGR;15")) {
-                    UINT16 v = ((((UINT16)r) << 7) & 0x7c00) +
-                               ((((UINT16)g) << 2) & 0x03e0) +
-                               ((((UINT16)b) >> 3) & 0x001f);
+                    UINT16 v = ((((UINT16)b) << 10) & 0x7c00) +
+                               ((((UINT16)g) << 5) & 0x03e0) +
+                               ((((UINT16)r) >> 0) & 0x001f);
 
                     ink[0] = (UINT8)v;
                     ink[1] = (UINT8)(v >> 8);
                     ink[2] = ink[3] = 0;
                     return ink;
                 } else if (!strcmp(im->mode, "BGR;16")) {
-                    UINT16 v = ((((UINT16)r) << 8) & 0xf800) +
-                               ((((UINT16)g) << 3) & 0x07e0) +
-                               ((((UINT16)b) >> 3) & 0x001f);
+                    UINT16 v = ((((UINT16)b) << 11) & 0xf800) +
+                               ((((UINT16)g) << 5) & 0x07e0) +
+                               ((((UINT16)r) >> 0) & 0x001f);
                     ink[0] = (UINT8)v;
                     ink[1] = (UINT8)(v >> 8);
                     ink[2] = ink[3] = 0;

src/libImaging/Access.c

@@ -92,19 +92,19 @@ get_pixel_BGR15(Imaging im, int x, int y, void *color) {
     UINT8 *in = (UINT8 *)&im->image8[y][x * 2];
     UINT16 pixel = in[0] + (in[1] << 8);
     char *out = color;
-    out[0] = (pixel & 31) * 255 / 31;
-    out[1] = ((pixel >> 5) & 31) * 255 / 31;
-    out[2] = ((pixel >> 10) & 31) * 255 / 31;
+    out[0] = (pixel >> 10) & 31;
+    out[1] = (pixel >> 5) & 31;
+    out[2] = pixel & 31;
 }
 
 static void
 get_pixel_BGR16(Imaging im, int x, int y, void *color) {
     UINT8 *in = (UINT8 *)&im->image8[y][x * 2];
     UINT16 pixel = in[0] + (in[1] << 8);
     char *out = color;
-    out[0] = (pixel & 31) * 255 / 31;
-    out[1] = ((pixel >> 5) & 63) * 255 / 63;
-    out[2] = ((pixel >> 11) & 31) * 255 / 31;
+    out[0] = (pixel >> 11) & 31;
+    out[1] = (pixel >> 5) & 63;
+    out[2] = pixel & 31;
 }
 
 static void