Fix #155982: Cycles denoise animation operator fails for multi-part EXR

Support reading multi-part EXR in this code, and add a test. Also fixes
the denoise_animation test being disabled.

Regression from be1619f4ad.

Pull Request: https://projects.blender.org/blender/blender/pulls/156040

intern/cycles/session/denoising.cpp

@@ -465,6 +465,50 @@ bool DenoiseImage::read_previous_pixels(const DenoiseImageLayer &layer,
   return true;
 }
 
+bool DenoiseImage::read_pixels(ImageInput *in)
+{
+  /* For multi-part EXR each subimage contains a pass, so we'll read them all. */
+  const int num_subimages = in_spec.get_int_attribute("oiio:subimages", 1);
+  vector<string> channelnames;
+  vector<int> num_channels_subimage;
+  for (int s = 0; s < num_subimages; s++) {
+    const ImageSpec spec = in->spec(s);
+    num_channels_subimage.push_back(spec.nchannels);
+    for (const string &name : spec.channelnames) {
+      channelnames.push_back(name);
+    }
+  }
+
+  num_channels = int(channelnames.size());
+  pixels.resize(size_t(width) * size_t(height) * num_channels);
+
+  /* Read all channels from each subimage. */
+  const int64_t xstride = int64_t(num_channels) * sizeof(float);
+  size_t channel_offset = 0;
+  for (size_t s = 0; s < num_channels_subimage.size(); s++) {
+    if (!in->read_image(s,
+                        0,
+                        0,
+                        num_channels_subimage[s],
+                        TypeDesc::FLOAT,
+                        pixels.data() + channel_offset,
+                        xstride))
+    {
+      return false;
+    }
+    channel_offset += num_channels_subimage[s];
+  }
+
+  /* Update in_spec to reflect the flattened channel list for use in parse_channels. */
+  in->seek_subimage(0, 0);
+  in_spec.channelnames = channelnames;
+  in_spec.nchannels = num_channels;
+  in_spec.channelformats.clear();
+  in_spec.format = TypeDesc::FLOAT;
+
+  return true;
+}
+
 bool DenoiseImage::load(const string &in_filepath, string &error)
 {
   if (!Filesystem::is_regular(in_filepath)) {
@@ -481,7 +525,11 @@ bool DenoiseImage::load(const string &in_filepath, string &error)
   in_spec = in->spec();
   width = in_spec.width;
   height = in_spec.height;
-  num_channels = in_spec.nchannels;
+
+  if (!read_pixels(in.get())) {
+    error = "Failed to read image: " + in_filepath;
+    return false;
+  }
 
   if (!parse_channels(in_spec, error)) {
     return false;
@@ -492,16 +540,6 @@ bool DenoiseImage::load(const string &in_filepath, string &error)
     return false;
   }
 
-  const size_t num_pixels = (size_t)width * (size_t)height;
-  pixels.resize(num_pixels * num_channels);
-
-  /* Read all channels into buffer. Reading all channels at once is faster
-   * than individually due to interleaved EXR channel storage. */
-  if (!in->read_image(0, 0, 0, num_channels, TypeDesc::FLOAT, pixels.data())) {
-    error = "Failed to read image: " + in_filepath;
-    return false;
-  }
-
   return true;
 }
 

intern/cycles/session/denoising.h

@@ -134,6 +134,10 @@ class DenoiseImage {
    * fill layers and set up the output channels and passthrough map. */
   bool parse_channels(const ImageSpec &in_spec, string &error);
 
+  /* Read pixels from an open ImageInput into the pixels buffer.
+   * Updates in_spec, num_channels, and pixels. */
+  bool read_pixels(ImageInput *in);
+
   void close_input();
 };
 

tests/files/render/denoise_animation/cycles_renders/denoise.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:85112b0a7f123fa09809e0b6164331e40ff788cf78f91260809a20799501c1a6
-size 24531
+oid sha256:e5d6c222c00115583b7e893c3525bdbda837311db39561c3e506d200d77c7b13
+size 22554

tests/files/render/denoise_animation/cycles_renders/denoise_multipart.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:e5d6c222c00115583b7e893c3525bdbda837311db39561c3e506d200d77c7b13
+size 22554

tests/files/render/denoise_animation/cycles_renders/merge_denoise.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:79f308618c8a72ccf25f3650564372fb4e1007b1ed3b554d800545304298fbdc
-size 30455
+oid sha256:154920bfd7e39096fd49bc75fd9a2e092f756c13fb19d425cff9465bd02563f4
+size 22481

tests/files/render/denoise_animation/denoise.blend.input.exr

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:0155d0a2a9150c01e4aee55877783ae2b95cc06052b5b2f38325e3377ea3dfef
-size 412358
+oid sha256:b8161abd02d8a464c030d2b37a470fda2f97f920d287f129c49adf95780c6ed2
+size 157999

tests/files/render/denoise_animation/denoise_multipart.blend

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:bfe1afee3a6601bb8d855a0493f849f372ba8652d4972bd2749b9ff51212f68b
+size 143992

tests/files/render/denoise_animation/denoise_multipart.blend.input.exr

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:eb3a0acdfb0a8f5d40f10da685214c57a382d29697fcc1f6765e95eb3a5994a2
+size 163475

tests/files/render/denoise_animation/merge_denoise.blend.input1.exr

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:733c1365516e032bae340d310dc3d8a39b584ddd6de172dbbf93506defbd4073
-size 412358
+oid sha256:1312b3ebe11763287b25bad11ca219000ffddb78111417e150f15e5532c3cf02
+size 157999

tests/files/render/denoise_animation/merge_denoise.blend.input2.exr

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:e89d6367d1f2ac244b15f75425d0b5fc1c27af34acaf40483b80bd3bc32c26e8
-size 412559
+oid sha256:0959a36f703726f505c672cedac97d73256f3e39f97d584a6fd4f25191779087
+size 157977

tests/python/CMakeLists.txt

@@ -851,7 +851,7 @@ if((WITH_CYCLES OR WITH_GPU_RENDER_TESTS) AND TEST_SRC_DIR_EXISTS)
   endif()
 
   if(WITH_OPENIMAGEDENOISE)
-    list(APPEND render_tests denoise)
+    list(APPEND render_tests denoise denoise_animation)
   endif()
 
   # Disabled until new OpenPGL version with deterministic results.