[Fix] Add Support for Images not Div by 16 (Diff. JPEG) (#2865)

* Add support for images not div by 16 (diff JPEG)

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update kornia/enhance/jpeg.py

Co-authored-by: Jian Shi <sj8716643@126.com>

* Remove if statements (both in pad and crop)

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Jian Shi <sj8716643@126.com>

kornia/enhance/jpeg.py

@@ -1,6 +1,10 @@
 from __future__ import annotations
 
+import math
+from typing import Tuple
+
 import torch
+import torch.nn.functional as F
 
 from kornia.color import rgb_to_ycbcr, ycbcr_to_rgb
 from kornia.constants import pi
@@ -344,6 +348,27 @@ def _jpeg_decode(
     return rgb_decoded
 
 
+def _perform_padding(image: Tensor) -> Tuple[Tensor, int, int]:
+    """Pads a given image to be dividable by 16.
+
+    Args:
+        image: Image of the shape :math:`(*, 3, H, W)`.
+
+    Returns:
+        image_padded: Padded image of the shape :math:`(*, 3, H_{new}, W_{new})`.
+        h_pad: Padded pixels along the horizontal axis.
+        w_pad: Padded pixels along the vertical axis.
+    """
+    # Get spatial dimensions of the image
+    H, W = image.shape[-2:]
+    # Compute horizontal and vertical padding
+    h_pad: int = math.ceil(H / 16) * 16 - H
+    w_pad: int = math.ceil(W / 16) * 16 - W
+    # Perform padding (we follow JPEG and pad only the bottom and right side of the image)
+    image_padded: Tensor = F.pad(image, (0, w_pad, 0, h_pad), "replicate")
+    return image_padded, h_pad, w_pad
+
+
 @perform_keep_shape_image
 def jpeg_codec_differentiable(
     image_rgb: Tensor,
@@ -437,10 +462,6 @@ def jpeg_codec_differentiable(
     KORNIA_CHECK_IS_TENSOR(quantization_table_c)
     # Check shape of inputs
     KORNIA_CHECK_SHAPE(image_rgb, ["*", "3", "H", "W"])
-    KORNIA_CHECK(
-        (image_rgb.shape[-1] % 16 == 0) and (image_rgb.shape[-2] % 16 == 0),
-        f"image dimension must be divisible by 16. Got the shape {image_rgb.shape}.",
-    )
     KORNIA_CHECK_SHAPE(jpeg_quality, ["B"])
     # Add batch dimension to quantization tables if needed
     if quantization_table_y.ndim == 2:
@@ -456,6 +477,8 @@ def jpeg_codec_differentiable(
         f"JPEG quality is out of range. Expected range is [0, 100], "
         f"got [{jpeg_quality.amin().item()}, {jpeg_quality.amax().item()}]. Consider clipping jpeg_quality.",
     )
+    # Pad the image to a shape dividable by 16
+    image_rgb, h_pad, w_pad = _perform_padding(image_rgb)
     # Get height and shape
     H, W = image_rgb.shape[-2:]
     # Check matching batch dimensions
@@ -499,8 +522,8 @@ def jpeg_codec_differentiable(
     )
     # Clip coded image
     image_rgb_jpeg = differentiable_clipping(input=image_rgb_jpeg, min_val=0.0, max_val=255.0)
-    # Back to original shape
-    # image_rgb_jpeg = image_rgb_jpeg.view(original_shape)
+    # Crop the image again to the original shape
+    image_rgb_jpeg = image_rgb_jpeg[..., : H - h_pad, : W - w_pad]
     return image_rgb_jpeg
 
 

tests/enhance/test_jpeg.py

@@ -16,6 +16,15 @@ def test_smoke(self, device, dtype) -> None:
         assert img_jpeg is not None
         assert img_jpeg.shape == img.shape
 
+    def test_smoke_not_div_by_16(self, device, dtype) -> None:
+        """This test standard usage."""
+        B, H, W = 2, 33, 33
+        img = torch.rand(B, 3, H, W, device=device, dtype=dtype)
+        jpeg_quality = torch.randint(low=0, high=100, size=(B,), device=device, dtype=dtype)
+        img_jpeg = kornia.enhance.jpeg_codec_differentiable(img, jpeg_quality)
+        assert img_jpeg is not None
+        assert img_jpeg.shape == img.shape
+
     def test_multi_batch(self, device, dtype) -> None:
         """Here we test two batch dimensions."""
         B, H, W = 4, 32, 32
@@ -81,13 +90,6 @@ def test_exception(self, device, dtype) -> None:
             kornia.enhance.jpeg_codec_differentiable(img, jpeg_quality)
         assert "shape must be [" in str(errinfo)
 
-        with pytest.raises(Exception) as errinfo:
-            B, H, W = 2, 31, 31
-            img = torch.rand(B, 3, H, W, device=device, dtype=dtype)
-            jpeg_quality = torch.randint(low=0, high=100, size=(B,), device=device, dtype=dtype)
-            kornia.enhance.jpeg_codec_differentiable(img, jpeg_quality)
-        assert "divisible" in str(errinfo)
-
         with pytest.raises(Exception) as errinfo:
             B, H, W = 4, 32, 32
             img = torch.rand(B, 3, H, W, device=device, dtype=dtype)