Issue 2075 : Apply RGB on transpose matrices. (#2206)

* adding unit test for applyRGB buffer, check in the applyRGB if the buffer is C order or not, for now throw error

Signed-off-by: Afsaneh Sheikhmiri <afsaneh.sheikhmiri@autodesk.com>

* Adsk Contrib - Detect C/F order, if not C order : RuntimeError shown, test is still not passing

Signed-off-by: Afsaneh Sheikhmiri <afsaneh.sheikhmiri@autodesk.com>

* remove 1d arrays from the test, since even after Transpose, 1d arrays are still contiguous

Signed-off-by: Afsaneh Sheikhmiri <afsaneh.sheikhmiri@autodesk.com>

---------

Signed-off-by: Afsaneh Sheikhmiri <afsaneh.sheikhmiri@autodesk.com>
Co-authored-by: Doug Walker <doug.walker@autodesk.com>

Author: Asheikhm

src/bindings/python/PyCPUProcessor.cpp

@@ -96,7 +96,10 @@ written to the dstImgDesc image, leaving srcImgDesc unchanged.
                 py::buffer_info info = data.request();
                 checkBufferDivisible(info, 3);
 
-                // Interpret as single row of RGB pixels
+                // --- detect C-contiguous ---
+                checkCContiguousArray(info);
+
+                // --- proceed normally ---
                 BitDepth bitDepth = getBufferBitDepth(info);
 
                 py::gil_scoped_release release;
@@ -115,6 +118,7 @@ written to the dstImgDesc image, leaving srcImgDesc unchanged.
                                     chanStrideBytes, 
                                     xStrideBytes, 
                                     yStrideBytes);
+
                 self->apply(img);
             },
              "data"_a, 
@@ -171,6 +175,8 @@ float values is returned, leaving the input list unchanged.
                 py::buffer_info info = data.request();
                 checkBufferDivisible(info, 4);
 
+                // --- detect C-contiguous ---
+                checkCContiguousArray(info);
                 // Interpret as single row of RGBA pixels
                 BitDepth bitDepth = getBufferBitDepth(info);
 

src/bindings/python/PyUtils.cpp

@@ -179,6 +179,27 @@ void checkBufferType(const py::buffer_info & info, BitDepth bitDepth)
     checkBufferType(info, bitDepthToDtype(bitDepth));
 }
 
+void checkCContiguousArray(const py::buffer_info & info)
+{
+    bool isC = true;
+    ptrdiff_t itemsize = info.itemsize;
+    auto shape = info.shape;
+    auto strides = info.strides;
+    py::ssize_t ndim = info.ndim;
+
+    ptrdiff_t expected = itemsize;
+    for (py::ssize_t i = ndim - 1; i >= 0; --i)
+    {
+        if (strides[i] != expected) { isC = false; break; }
+        expected *= shape[i];
+    }
+
+    if (!isC)
+    {
+        throw std::runtime_error("function only supports C-contiguous (row-major) arrays");
+    }
+}
+
 void checkBufferDivisible(const py::buffer_info & info, py::ssize_t numChannels)
 {
     if (info.size % numChannels != 0)

src/bindings/python/PyUtils.h

@@ -89,6 +89,9 @@ unsigned long getBufferLut3DGridSize(const py::buffer_info & info);
 // Throw if vector size is not divisible by channel count
 void checkVectorDivisible(const std::vector<float> & pixel, size_t numChannels);
 
+// Throw if array is not C-contiguous
+void checkCContiguousArray(const py::buffer_info & info);
+
 } // namespace OCIO_NAMESPACE
 
 #endif // INCLUDED_OCIO_PYUTILS_H

tests/python/CPUProcessorTest.py

@@ -19,7 +19,7 @@
 
 
 class CPUProcessorTest(unittest.TestCase):
-    FLOAT_DELTA = 1e+5
+    FLOAT_DELTA = 1e-5
     UINT_DELTA = 1
 
     @classmethod
@@ -385,6 +385,28 @@ def test_apply_rgb_list(self):
                 delta=self.FLOAT_DELTA
             )
 
+    def test_apply_rgb_buffer_column_major(self):
+        if not np:
+            logger.warning("NumPy not found. Skipping test!")
+            return
+
+        for arr, cpu_proc_fwd in [
+            (self.float_rgb_2d, self.default_cpu_proc_fwd),
+            (self.float_rgb_3d, self.default_cpu_proc_fwd),
+            (self.half_rgb_2d, self.half_cpu_proc_fwd),
+            (self.half_rgb_3d, self.half_cpu_proc_fwd),
+            (self.uint16_rgb_2d, self.uint16_cpu_proc_fwd),
+            (self.uint16_rgb_3d, self.uint16_cpu_proc_fwd),
+            (self.uint8_rgb_2d, self.uint8_cpu_proc_fwd),
+            (self.uint8_rgb_3d, self.uint8_cpu_proc_fwd),
+        ]:
+            # Transpose to F-order (column-major)
+            arr_copy = arr.copy().T
+
+            # Expect runtime error for non-C-contiguous array
+            with self.assertRaises(RuntimeError):
+                cpu_proc_fwd.applyRGB(arr_copy)
+
     def test_apply_rgb_buffer(self):
         if not np:
             logger.warning("NumPy not found. Skipping test!")
@@ -627,3 +649,48 @@ def test_apply_rgba_buffer(self):
                         arr.flat[i],
                         delta=self.UINT_DELTA
                     )
+
+    def test_apply_rgba_buffer_column_major(self):
+        if not np:
+            logger.warning("NumPy not found. Skipping test!")
+            return
+
+        for arr, cpu_proc_fwd in [
+            (
+                self.float_rgba_2d, 
+                self.default_cpu_proc_fwd
+            ),
+            (
+                self.float_rgba_3d, 
+                self.default_cpu_proc_fwd
+            ),
+            (
+                self.half_rgba_2d, 
+                self.half_cpu_proc_fwd
+            ),
+            (
+                self.half_rgba_3d, 
+                self.half_cpu_proc_fwd
+            ),
+            (
+                self.uint16_rgba_2d, 
+                self.uint16_cpu_proc_fwd
+            ),
+            (
+                self.uint16_rgba_3d, 
+                self.uint16_cpu_proc_fwd
+            ),
+            (
+                self.uint8_rgba_2d, 
+                self.uint8_cpu_proc_fwd
+            ),
+            (
+                self.uint8_rgba_3d, 
+                self.uint8_cpu_proc_fwd,
+            ),
+        ]:
+            # Transpose to F-order (column-major)
+            arr_copy = arr.copy().T
+            # Expect runtime error for non-C-contiguous array
+            with self.assertRaises(RuntimeError):
+                cpu_proc_fwd.applyRGBA(arr_copy)