Cleanup/refactor of decoders and related tests

test/test_image.py

@@ -42,6 +42,19 @@
 IS_WINDOWS = sys.platform in ("win32", "cygwin")
 IS_MACOS = sys.platform == "darwin"
 PILLOW_VERSION = tuple(int(x) for x in PILLOW_VERSION.split("."))
+WEBP_TEST_IMAGES_DIR = os.environ.get("WEBP_TEST_IMAGES_DIR", "")
+
+# Hacky way of figuring out whether we compiled with libavif/libheif (those are
+# currenlty disabled by default)
+try:
+    _decode_avif(torch.arange(10, dtype=torch.uint8))
+except Exception as e:
+    DECODE_AVIF_ENABLED = "torchvision not compiled with libavif support" not in str(e)
+
+try:
+    _decode_heic(torch.arange(10, dtype=torch.uint8))
+except Exception as e:
+    DECODE_HEIC_ENABLED = "torchvision not compiled with libheif support" not in str(e)
 
 
 def _get_safe_image_name(name):
@@ -149,17 +162,6 @@ def test_invalid_exif(tmpdir, size):
     torch.testing.assert_close(expected, output)
 
 
-def test_decode_jpeg_errors():
-    with pytest.raises(RuntimeError, match="Expected a non empty 1-dimensional tensor"):
-        decode_jpeg(torch.empty((100, 1), dtype=torch.uint8))
-
-    with pytest.raises(RuntimeError, match="Expected a torch.uint8 tensor"):
-        decode_jpeg(torch.empty((100,), dtype=torch.float16))
-
-    with pytest.raises(RuntimeError, match="Not a JPEG file"):
-        decode_jpeg(torch.empty((100), dtype=torch.uint8))
-
-
 def test_decode_bad_huffman_images():
     # sanity check: make sure we can decode the bad Huffman encoding
     bad_huff = read_file(os.path.join(DAMAGED_JPEG, "bad_huffman.jpg"))
@@ -235,10 +237,6 @@ def test_decode_png(img_path, pil_mode, mode, scripted, decode_fun):
 
 
 def test_decode_png_errors():
-    with pytest.raises(RuntimeError, match="Expected a non empty 1-dimensional tensor"):
-        decode_png(torch.empty((), dtype=torch.uint8))
-    with pytest.raises(RuntimeError, match="Content is not png"):
-        decode_png(torch.randint(3, 5, (300,), dtype=torch.uint8))
     with pytest.raises(RuntimeError, match="Out of bound read in decode_png"):
         decode_png(read_file(os.path.join(DAMAGED_PNG, "sigsegv.png")))
     with pytest.raises(RuntimeError, match="Content is too small for png"):
@@ -864,20 +862,28 @@ def test_decode_gif(tmpdir, name, scripted):
             torch.testing.assert_close(tv_frame, pil_frame, atol=0, rtol=0)
 
 
-@pytest.mark.parametrize("decode_fun", (decode_gif, decode_webp))
-def test_decode_gif_webp_errors(decode_fun):
+decode_fun_and_match = [
+    (decode_png, "Content is not png"),
+    (decode_jpeg, "Not a JPEG file"),
+    (decode_gif, re.escape("DGifOpenFileName() failed - 103")),
+    (decode_webp, "WebPGetFeatures failed."),
+]
+if DECODE_AVIF_ENABLED:
+    decode_fun_and_match.append((_decode_avif, "BMFF parsing failed"))
+if DECODE_HEIC_ENABLED:
+    decode_fun_and_match.append((_decode_heic, "Invalid input: No 'ftyp' box"))
+
+
+@pytest.mark.parametrize("decode_fun, match", decode_fun_and_match)
+def test_decode_bad_encoded_data(decode_fun, match):
     encoded_data = torch.randint(0, 256, (100,), dtype=torch.uint8)
     with pytest.raises(RuntimeError, match="Input tensor must be 1-dimensional"):
         decode_fun(encoded_data[None])
     with pytest.raises(RuntimeError, match="Input tensor must have uint8 data type"):
         decode_fun(encoded_data.float())
     with pytest.raises(RuntimeError, match="Input tensor must be contiguous"):
         decode_fun(encoded_data[::2])
-    if decode_fun is decode_gif:
-        expected_match = re.escape("DGifOpenFileName() failed - 103")
-    elif decode_fun is decode_webp:
-        expected_match = "WebPGetFeatures failed."
-    with pytest.raises(RuntimeError, match=expected_match):
+    with pytest.raises(RuntimeError, match=match):
         decode_fun(encoded_data)
 
 
@@ -890,21 +896,27 @@ def test_decode_webp(decode_fun, scripted):
     img = decode_fun(encoded_bytes)
     assert img.shape == (3, 100, 100)
     assert img[None].is_contiguous(memory_format=torch.channels_last)
+    img += 123  # make sure image buffer wasn't freed by underlying decoding lib
 
 
-# This test is skipped because it requires webp images that we're not including
-# within the repo. The test images were downloaded from the different pages of
-# https://developers.google.com/speed/webp/gallery
-# Note that converting an RGBA image to RGB leads to bad results because the
-# transparent pixels aren't necessarily set to "black" or "white", they can be
-# random stuff. This is consistent with PIL results.
-@pytest.mark.skip(reason="Need to download test images first")
+# This test is skipped by default because it requires webp images that we're not
+# including within the repo. The test images were downloaded manually from the
+# different pages of https://developers.google.com/speed/webp/gallery
+@pytest.mark.skipif(not WEBP_TEST_IMAGES_DIR, reason="WEBP_TEST_IMAGES_DIR is not set")
 @pytest.mark.parametrize("decode_fun", (decode_webp, decode_image))
 @pytest.mark.parametrize("scripted", (False, True))
 @pytest.mark.parametrize(
-    "mode, pil_mode", ((ImageReadMode.RGB, "RGB"), (ImageReadMode.RGB_ALPHA, "RGBA"), (ImageReadMode.UNCHANGED, None))
+    "mode, pil_mode",
+    (
+        # Note that converting an RGBA image to RGB leads to bad results because the
+        # transparent pixels aren't necessarily set to "black" or "white", they can be
+        # random stuff. This is consistent with PIL results.
+        (ImageReadMode.RGB, "RGB"),
+        (ImageReadMode.RGB_ALPHA, "RGBA"),
+        (ImageReadMode.UNCHANGED, None),
+    ),
 )
-@pytest.mark.parametrize("filename", Path("/home/nicolashug/webp_samples").glob("*.webp"))
+@pytest.mark.parametrize("filename", Path(WEBP_TEST_IMAGES_DIR).glob("*.webp"), ids=lambda p: p.name)
 def test_decode_webp_against_pil(decode_fun, scripted, mode, pil_mode, filename):
     encoded_bytes = read_file(filename)
     if scripted:
@@ -915,9 +927,10 @@ def test_decode_webp_against_pil(decode_fun, scripted, mode, pil_mode, filename)
     pil_img = Image.open(filename).convert(pil_mode)
     from_pil = F.pil_to_tensor(pil_img)
     assert_equal(img, from_pil)
+    img += 123  # make sure image buffer wasn't freed by underlying decoding lib
 
 
-@pytest.mark.xfail(reason="AVIF support not enabled yet.")
+@pytest.mark.skipif(not DECODE_AVIF_ENABLED, reason="AVIF support not enabled.")
 @pytest.mark.parametrize("decode_fun", (_decode_avif, decode_image))
 @pytest.mark.parametrize("scripted", (False, True))
 def test_decode_avif(decode_fun, scripted):
@@ -927,12 +940,20 @@ def test_decode_avif(decode_fun, scripted):
     img = decode_fun(encoded_bytes)
     assert img.shape == (3, 100, 100)
     assert img[None].is_contiguous(memory_format=torch.channels_last)
+    img += 123  # make sure image buffer wasn't freed by underlying decoding lib
 
 
-@pytest.mark.xfail(reason="AVIF and HEIC support not enabled yet.")
 # Note: decode_image fails because some of these files have a (valid) signature
 # we don't recognize. We should probably use libmagic....
-@pytest.mark.parametrize("decode_fun", (_decode_avif, _decode_heic))
+decode_funs = []
+if DECODE_AVIF_ENABLED:
+    decode_funs.append(_decode_avif)
+if DECODE_HEIC_ENABLED:
+    decode_funs.append(_decode_heic)
+
+
+@pytest.mark.skipif(not decode_funs, reason="Built without avif and heic support.")
+@pytest.mark.parametrize("decode_fun", decode_funs)
 @pytest.mark.parametrize("scripted", (False, True))
 @pytest.mark.parametrize(
     "mode, pil_mode",
@@ -945,7 +966,7 @@ def test_decode_avif(decode_fun, scripted):
 @pytest.mark.parametrize(
     "filename", Path("/home/nicolashug/dev/libavif/tests/data/").glob("*.avif"), ids=lambda p: p.name
 )
-def test_decode_avif_against_pil(decode_fun, scripted, mode, pil_mode, filename):
+def test_decode_avif_heic_against_pil(decode_fun, scripted, mode, pil_mode, filename):
     if "reversed_dimg_order" in str(filename):
         # Pillow properly decodes this one, but we don't (order of parts of the
         # image is wrong). This is due to a bug that was recently fixed in
@@ -996,21 +1017,21 @@ def test_decode_avif_against_pil(decode_fun, scripted, mode, pil_mode, filename)
         g = make_grid([img, from_pil])
         F.to_pil_image(g).save((f"/home/nicolashug/out_images/{filename.name}.{pil_mode}.png"))
 
-    is__decode_heic = getattr(decode_fun, "__name__", getattr(decode_fun, "name", None)) == "_decode_heic"
-    if mode == ImageReadMode.RGB and not is__decode_heic:
+    is_decode_heic = getattr(decode_fun, "__name__", getattr(decode_fun, "name", None)) == "_decode_heic"
+    if mode == ImageReadMode.RGB and not is_decode_heic:
         # We don't compare torchvision's AVIF against PIL for RGB because
         # results look pretty different on RGBA images (other images are fine).
         # The result on torchvision basically just plainly ignores the alpha
         # channel, resuting in transparent pixels looking dark. PIL seems to be
         # using a sort of k-nn thing (Take a look at the resuting images)
         return
-    if filename.name == "sofa_grid1x5_420.avif" and is__decode_heic:
+    if filename.name == "sofa_grid1x5_420.avif" and is_decode_heic:
         return
 
     torch.testing.assert_close(img, from_pil, rtol=0, atol=3)
 
 
-@pytest.mark.xfail(reason="HEIC support not enabled yet.")
+@pytest.mark.skipif(not DECODE_HEIC_ENABLED, reason="HEIC support not enabled yet.")
 @pytest.mark.parametrize("decode_fun", (_decode_heic, decode_image))
 @pytest.mark.parametrize("scripted", (False, True))
 def test_decode_heic(decode_fun, scripted):
@@ -1020,6 +1041,7 @@ def test_decode_heic(decode_fun, scripted):
     img = decode_fun(encoded_bytes)
     assert img.shape == (3, 100, 100)
     assert img[None].is_contiguous(memory_format=torch.channels_last)
+    img += 123  # make sure image buffer wasn't freed by underlying decoding lib
 
 
 if __name__ == "__main__":

torchvision/csrc/io/image/common.cpp

@@ -0,0 +1,43 @@
+
+#include "common.h"
+#include <torch/torch.h>
+
+namespace vision {
+namespace image {
+
+void validate_encoded_data(const torch::Tensor& encoded_data) {
+  TORCH_CHECK(encoded_data.is_contiguous(), "Input tensor must be contiguous.");
+  TORCH_CHECK(
+      encoded_data.dtype() == torch::kU8,
+      "Input tensor must have uint8 data type, got ",
+      encoded_data.dtype());
+  TORCH_CHECK(
+      encoded_data.dim() == 1 && encoded_data.numel() > 0,
+      "Input tensor must be 1-dimensional and non-empty, got ",
+      encoded_data.dim(),
+      " dims  and ",
+      encoded_data.numel(),
+      " numels.");
+}
+
+bool should_this_return_rgb_or_rgba_let_me_know_in_the_comments_down_below_guys_see_you_in_the_next_video(
+    ImageReadMode mode,
+    bool has_alpha) {
+  // Return true if the calling decoding function should return a 3D RGB tensor,
+  // and false if it should return a 4D RGBA tensor.
+  // This function ignores the requested "grayscale" modes and treats it as
+  // "unchanged", so it should only used on decoders who don't support grayscale
+  // outputs.
+
+  if (mode == IMAGE_READ_MODE_RGB) {
+    return true;
+  }
+  if (mode == IMAGE_READ_MODE_RGB_ALPHA) {
+    return false;
+  }
+  // From here we assume mode is "unchanged", even for grayscale ones.
+  return !has_alpha;
+}
+
+} // namespace image
+} // namespace vision

torchvision/csrc/io/image/image_read_mode.h → torchvision/csrc/io/image/common.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <stdint.h>
+#include <torch/torch.h>
 
 namespace vision {
 namespace image {
@@ -13,5 +14,11 @@ const ImageReadMode IMAGE_READ_MODE_GRAY_ALPHA = 2;
 const ImageReadMode IMAGE_READ_MODE_RGB = 3;
 const ImageReadMode IMAGE_READ_MODE_RGB_ALPHA = 4;
 
+void validate_encoded_data(const torch::Tensor& encoded_data);
+
+bool should_this_return_rgb_or_rgba_let_me_know_in_the_comments_down_below_guys_see_you_in_the_next_video(
+    ImageReadMode mode,
+    bool has_alpha);
+
 } // namespace image
 } // namespace vision

torchvision/csrc/io/image/cpu/decode_avif.cpp

@@ -1,4 +1,5 @@
 #include "decode_avif.h"
+#include "../common.h"
 
 #if AVIF_FOUND
 #include "avif/avif.h"
@@ -33,16 +34,7 @@ torch::Tensor decode_avif(
   // Refer there for more detail about what each function does, and which
   // structure/data is available after which call.
 
-  TORCH_CHECK(encoded_data.is_contiguous(), "Input tensor must be contiguous.");
-  TORCH_CHECK(
-      encoded_data.dtype() == torch::kU8,
-      "Input tensor must have uint8 data type, got ",
-      encoded_data.dtype());
-  TORCH_CHECK(
-      encoded_data.dim() == 1,
-      "Input tensor must be 1-dimensional, got ",
-      encoded_data.dim(),
-      " dims.");
+  validate_encoded_data(encoded_data);
 
   DecoderPtr decoder(avifDecoderCreate());
   TORCH_CHECK(decoder != nullptr, "Failed to create avif decoder.");
@@ -60,6 +52,7 @@ torch::Tensor decode_avif(
       result == AVIF_RESULT_OK,
       "avifDecoderParse failed: ",
       avifResultToString(result));
+  printf("avif num images = %d\n", decoder->imageCount);
   TORCH_CHECK(
       decoder->imageCount == 1, "Avif file contains more than one image");
 
@@ -78,18 +71,9 @@ torch::Tensor decode_avif(
   auto use_uint8 = (decoder->image->depth <= 8);
   rgb.depth = use_uint8 ? 8 : 16;
 
-  if (mode != IMAGE_READ_MODE_UNCHANGED && mode != IMAGE_READ_MODE_RGB &&
-      mode != IMAGE_READ_MODE_RGB_ALPHA) {
-    // Other modes aren't supported, but we don't error or even warn because we
-    // have generic entry points like decode_image which may support all modes,
-    // it just depends on the underlying decoder.
-    mode = IMAGE_READ_MODE_UNCHANGED;
-  }
-
-  // If return_rgb is false it means we return rgba - nothing else.
   auto return_rgb =
-      (mode == IMAGE_READ_MODE_RGB ||
-       (mode == IMAGE_READ_MODE_UNCHANGED && !decoder->alphaPresent));
+      should_this_return_rgb_or_rgba_let_me_know_in_the_comments_down_below_guys_see_you_in_the_next_video(
+          mode, decoder->alphaPresent);
 
   auto num_channels = return_rgb ? 3 : 4;
   rgb.format = return_rgb ? AVIF_RGB_FORMAT_RGB : AVIF_RGB_FORMAT_RGBA;

torchvision/csrc/io/image/cpu/decode_avif.h

@@ -1,7 +1,7 @@
 #pragma once
 
 #include <torch/types.h>
-#include "../image_read_mode.h"
+#include "../common.h"
 
 namespace vision {
 namespace image {

torchvision/csrc/io/image/cpu/decode_gif.cpp

@@ -1,5 +1,6 @@
 #include "decode_gif.h"
 #include <cstring>
+#include "../common.h"
 #include "giflib/gif_lib.h"
 
 namespace vision {
@@ -34,16 +35,7 @@ torch::Tensor decode_gif(const torch::Tensor& encoded_data) {
   // Refer over there for more details on the libgif API, API ref, and a
   // detailed description of the GIF format.
 
-  TORCH_CHECK(encoded_data.is_contiguous(), "Input tensor must be contiguous.");
-  TORCH_CHECK(
-      encoded_data.dtype() == torch::kU8,
-      "Input tensor must have uint8 data type, got ",
-      encoded_data.dtype());
-  TORCH_CHECK(
-      encoded_data.dim() == 1,
-      "Input tensor must be 1-dimensional, got ",
-      encoded_data.dim(),
-      " dims.");
+  validate_encoded_data(encoded_data);
 
   int error = D_GIF_SUCCEEDED;
 

torchvision/csrc/io/image/cpu/decode_heic.cpp

@@ -1,4 +1,5 @@
 #include "decode_heic.h"
+#include "../common.h"
 
 #if HEIC_FOUND
 #include "libheif/heif_cxx.h"
@@ -19,26 +20,8 @@ torch::Tensor decode_heic(
 torch::Tensor decode_heic(
     const torch::Tensor& encoded_data,
     ImageReadMode mode) {
-  TORCH_CHECK(encoded_data.is_contiguous(), "Input tensor must be contiguous.");
-  TORCH_CHECK(
-      encoded_data.dtype() == torch::kU8,
-      "Input tensor must have uint8 data type, got ",
-      encoded_data.dtype());
-  TORCH_CHECK(
-      encoded_data.dim() == 1,
-      "Input tensor must be 1-dimensional, got ",
-      encoded_data.dim(),
-      " dims.");
-
-  if (mode != IMAGE_READ_MODE_UNCHANGED && mode != IMAGE_READ_MODE_RGB &&
-      mode != IMAGE_READ_MODE_RGB_ALPHA) {
-    // Other modes aren't supported, but we don't error or even warn because we
-    // have generic entry points like decode_image which may support all modes,
-    // it just depends on the underlying decoder.
-    mode = IMAGE_READ_MODE_UNCHANGED;
-  }
+  validate_encoded_data(encoded_data);
 
-  // If return_rgb is false it means we return rgba - nothing else.
   auto return_rgb = true;
 
   int height = 0;
@@ -82,8 +65,8 @@ torch::Tensor decode_heic(
     bit_depth = handle.get_luma_bits_per_pixel();
 
     return_rgb =
-        (mode == IMAGE_READ_MODE_RGB ||
-         (mode == IMAGE_READ_MODE_UNCHANGED && !handle.has_alpha_channel()));
+        should_this_return_rgb_or_rgba_let_me_know_in_the_comments_down_below_guys_see_you_in_the_next_video(
+            mode, handle.has_alpha_channel());
 
     height = handle.get_height();
     width = handle.get_width();