Added support for 1 mode images

Author: radarhere

Tests/images/jxl/hopper_bw_500.jxl

@@ -6,7 +6,11 @@
 
 from PIL import Image, JpegXlImagePlugin, features
 
-from .helper import assert_image_similar_tofile, skip_unless_feature
+from .helper import (
+    assert_image_equal_tofile,
+    assert_image_similar_tofile,
+    skip_unless_feature,
+)
 
 try:
     from PIL import _jpegxl
@@ -34,12 +38,18 @@ def test_version(self) -> None:
         assert version is not None
         assert re.search(r"\d+\.\d+\.\d+$", version)
 
-    def test_read_rgb(self) -> None:
-        """
-        Can we read an RGB mode JPEG XL file without error?
-        Does it have the bits we expect?
-        """
+    def test_read_1(self) -> None:
+        with Image.open("Tests/images/jxl/hopper_bw_500.jxl") as im:
+            assert im.mode == "1"
+            assert im.size == (500, 500)
+            assert im.format == "JPEG XL"
+            im.getdata()
+
+            # generated with:
+            # cjxl hopper_bw_500.jxl hopper_bw_500.jxl
+            assert_image_equal_tofile(im, "Tests/images/hopper_bw_500.png")
 
+    def test_read_rgb(self) -> None:
         with Image.open("Tests/images/hopper.jxl") as im:
             assert im.mode == "RGB"
             assert im.size == (128, 128)
@@ -63,10 +73,6 @@ def test_read_rgba(self) -> None:
             assert_image_similar_tofile(im, "Tests/images/transparent.png", 1)
 
     def test_read_i16(self) -> None:
-        """
-        Can we read 16-bit Grayscale JPEG XL image?
-        """
-
         with Image.open("Tests/images/jxl/16bit_subcutaneous.cropped.jxl") as im:
             assert im.mode == "I;16"
             assert im.size == (128, 64)
@@ -81,6 +87,5 @@ def test_JpegXlDecode_with_invalid_args(self) -> None:
         """
         Calling decoder functions with no arguments should result in an error.
         """
-
         with pytest.raises(TypeError):
             _jpegxl.JpegXlDecoder()

Tests/test_file_jxl.py

@@ -55,7 +55,8 @@ def _open(self) -> None:
                 self.info["exif"] = exif[exif_start_offset + 4 :]
         if xmp := self._decoder.get_xmp():
             self.info["xmp"] = xmp
-        self.tile = [ImageFile._Tile("raw", (0, 0) + self.size, 0, self.mode)]
+        rawmode = "L" if self.mode == "1" else self.mode
+        self.tile = [ImageFile._Tile("raw", (0, 0) + self.size, 0, rawmode)]
 
     @property
     def n_frames(self) -> int:

src/PIL/JpegXlImagePlugin.py

@@ -29,6 +29,9 @@ _jxl_get_pixel_format(JxlPixelFormat *pf, const JxlBasicInfo *bi) {
 char *
 _jxl_get_mode(const JxlBasicInfo *bi) {
     if (bi->num_color_channels == 1 && !bi->alpha_bits) {
+        if (bi->bits_per_sample == 1) {
+            return "1";
+        }
         if (bi->bits_per_sample == 16) {
             return "I;16";
         }

src/_jpegxl.c

@@ -256,6 +256,14 @@ unpack18(UINT8 *out, const UINT8 *in, int pixels) {
     }
 }
 
+static void
+unpack1L(UINT8 *out, const UINT8 *in, int pixels) {
+    int i;
+    for (i = 0; i < pixels; i++) {
+        out[i] = in[i] > 128 ? 255 : 0;
+    }
+}
+
 /* Unpack to "L" image */
 
 static void
@@ -1564,6 +1572,7 @@ static struct {
     {IMAGING_MODE_1, IMAGING_RAWMODE_1_R, 1, unpack1R},
     {IMAGING_MODE_1, IMAGING_RAWMODE_1_IR, 1, unpack1IR},
     {IMAGING_MODE_1, IMAGING_RAWMODE_1_8, 8, unpack18},
+    {IMAGING_MODE_1, IMAGING_RAWMODE_L, 8, unpack1L},
 
     /* grayscale */
     {IMAGING_MODE_L, IMAGING_RAWMODE_L_2, 2, unpackL2},