Fix support for compressing mono images by respecting mode to determi…

…ne depth (#4847)

### What
 - Resolves: #4846

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
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* Using examples from latest `main` build:
[app.rerun.io](https://app.rerun.io/pr/4847/index.html?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[app.rerun.io](https://app.rerun.io/pr/4847/index.html?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG

- [PR Build Summary](https://build.rerun.io/pr/4847)
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preview](https://rerun.io/preview/deef4d8eb0369c94bbc7d29b100e021802e29c9b/docs)
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rerun_py/rerun_sdk/rerun/_image.py

@@ -141,10 +141,17 @@ def __init__(
             tensor_buffer = TensorBuffer(np.frombuffer(np_buffer, dtype=np.uint8))
             tensor_buffer.kind = "jpeg"
 
+            if img_data.mode == "L":
+                depth = 1
+            elif img_data.mode == "RGB":
+                depth = 3
+            else:
+                raise ValueError(f"Unsupported JPEG mode: {img_data.mode}")
+
             tensor_shape = (
                 TensorDimension(img_data.height, "height"),
                 TensorDimension(img_data.width, "width"),
-                TensorDimension(3, "depth"),
+                TensorDimension(depth, "depth"),
             )
             tensor_data = TensorData(buffer=tensor_buffer, shape=tensor_shape)
         else:

rerun_py/tests/unit/test_image_encoded.py

@@ -17,6 +17,7 @@ def test_image_encoded_png() -> None:
 
     assert img.data.shape[0].size == 200
     assert img.data.shape[1].size == 300
+    assert img.data.shape[2].size == 4
     assert img.data.buffer.kind == "u8"
 
 
@@ -28,8 +29,26 @@ def test_image_encoded_jpg() -> None:
 
     img = rr.ImageEncoded(path=file_path)
 
+    assert len(img.data.shape) == 3
     assert img.data.shape[0].size == 200
     assert img.data.shape[1].size == 300
+    assert img.data.shape[2].size == 3
+
+    assert img.data.buffer.kind == "jpeg"
+
+
+def test_image_encoded_mono_jpg() -> None:
+    _, file_path = tempfile.mkstemp(suffix=".jpg")
+
+    image = Image.new("L", (300, 200), color=0)
+    image.save(file_path)
+
+    img = rr.ImageEncoded(path=file_path)
+
+    assert len(img.data.shape) == 3
+    assert img.data.shape[0].size == 200
+    assert img.data.shape[1].size == 300
+    assert img.data.shape[2].size == 1
     assert img.data.buffer.kind == "jpeg"
 
 
@@ -41,13 +60,41 @@ def test_image_encoded_jpg_from_bytes() -> None:
 
     img = rr.ImageEncoded(contents=bin)
 
+    assert len(img.data.shape) == 3
+    assert img.data.shape[0].size == 200
+    assert img.data.shape[1].size == 300
+    assert img.data.shape[2].size == 3
+    assert img.data.buffer.kind == "jpeg"
+
+    bin.seek(0)
+    img = rr.ImageEncoded(contents=bin.read())
+
+    assert len(img.data.shape) == 3
+    assert img.data.shape[0].size == 200
+    assert img.data.shape[1].size == 300
+    assert img.data.shape[2].size == 3
+    assert img.data.buffer.kind == "jpeg"
+
+
+def test_image_encoded_mono_jpg_from_bytes() -> None:
+    bin = io.BytesIO()
+
+    image = Image.new("L", (300, 200), color=0)
+    image.save(bin, format="jpeg")
+
+    img = rr.ImageEncoded(contents=bin)
+
+    assert len(img.data.shape) == 3
     assert img.data.shape[0].size == 200
     assert img.data.shape[1].size == 300
+    assert img.data.shape[2].size == 1
     assert img.data.buffer.kind == "jpeg"
 
     bin.seek(0)
     img = rr.ImageEncoded(contents=bin.read())
 
+    assert len(img.data.shape) == 3
     assert img.data.shape[0].size == 200
     assert img.data.shape[1].size == 300
+    assert img.data.shape[2].size == 1
     assert img.data.buffer.kind == "jpeg"