Fix: Correct Bicubic Boundary Interpolation in CV-CUDA Resize (Tensor Path)

CMakeLists.txt

@@ -22,9 +22,9 @@ if(CMAKE_CUDA_ARCHITECTURES)
 endif()
 
 project(cvcuda
-        LANGUAGES C CXX
-        VERSION 0.16.0
-        DESCRIPTION "CUDA-accelerated Computer Vision algorithms"
+	LANGUAGES C CXX
+	VERSION 0.15.0
+	DESCRIPTION "CUDA-accelerated Computer Vision algorithms"
 )
 
 # Make sure the cuda host compiler agrees with what we're using,

src/cvcuda/priv/OpResize.cu

@@ -354,16 +354,14 @@ __global__ void CubicResize(SrcWrapper src, DstWrapper dst, int2 srcSize, int2 d
 
     if (dstCoord.y < dstSize.y && dstCoord.x < dstSize.x)
     {
-        float2 srcCoord = (cuda::DropCast<2>(dstCoord) + .5f) * scaleRatio - .5f;
-        int3   iSrcCoord{(int)floor(srcCoord.x), (int)floor(srcCoord.y), dstCoord.z};
-
-        float fx = srcCoord.x - iSrcCoord.x;
-        float fy = srcCoord.y - iSrcCoord.y;
+        const float2 srcCoord = (cuda::DropCast<2>(dstCoord) + .5f) * scaleRatio - .5f;
+        int3         baseCoord{(int)floor(srcCoord.x), (int)floor(srcCoord.y), dstCoord.z};
 
-        fx = (iSrcCoord.x < 1 || iSrcCoord.x >= srcSize.x - 3) ? 0 : fx;
+        const float fx = srcCoord.x - baseCoord.x;
+        const float fy = srcCoord.y - baseCoord.y;
 
-        iSrcCoord.y = cuda::max(1, cuda::min(iSrcCoord.y, srcSize.y - 3));
-        iSrcCoord.x = cuda::max(1, cuda::min(iSrcCoord.x, srcSize.x - 3));
+        const int xMax = srcSize.x - 1;
+        const int yMax = srcSize.y - 1;
 
         float wx[4];
         float wy[4];
@@ -376,10 +374,13 @@ __global__ void CubicResize(SrcWrapper src, DstWrapper dst, int2 srcSize, int2 d
 #pragma unroll
         for (int cy = -1; cy <= 2; cy++)
         {
+            const int sy = cuda::min(cuda::max(baseCoord.y + cy, 0), yMax);
 #pragma unroll
             for (int cx = -1; cx <= 2; cx++)
             {
-                sum += src[int3{iSrcCoord.x + cx, iSrcCoord.y + cy, iSrcCoord.z}] * (wx[cx + 1] * wy[cy + 1]);
+                const int sx = cuda::min(cuda::max(baseCoord.x + cx, 0), xMax);
+
+                sum += src[int3{sx, sy, baseCoord.z}] * (wx[cx + 1] * wy[cy + 1]);
             }
         }
 

src/cvcuda/priv/legacy/random_resized_crop.cu

@@ -181,7 +181,9 @@ __global__ void resize_cubic_v1(const SrcWrapper src, DstWrapper dst, int2 srcSi
         float fy = (float)((dst_y + 0.5f) * scale_y - 0.5f + top);
         int   sy = cuda::round<cuda::RoundMode::DOWN, int>(fy);
         fy -= sy;
-        sy = cuda::max(1, cuda::min(sy, height - 3));
+        const int syClamped = cuda::max(1, cuda::min(sy, height - 3));
+        fy += static_cast<float>(sy - syClamped);
+        sy = syClamped;
 
         const float A = -0.75f;
 
@@ -196,8 +198,9 @@ __global__ void resize_cubic_v1(const SrcWrapper src, DstWrapper dst, int2 srcSi
         float fx = (float)((dst_x + 0.5f) * scale_x - 0.5f + left);
         int   sx = cuda::round<cuda::RoundMode::DOWN, int>(fx);
         fx -= sx;
-        fx *= ((sx >= 1) && (sx < width - 3));
-        sx = cuda::max(1, cuda::min(sx, width - 3));
+        const int sxClamped = cuda::max(1, cuda::min(sx, width - 3));
+        fx += static_cast<float>(sx - sxClamped);
+        sx = sxClamped;
 
         float cX[4];
         cX[0] = ((A * (fx + 1.0f) - 5.0f * A) * (fx + 1.0f) + 8.0f * A) * (fx + 1.0f) - 4.0f * A;

src/cvcuda/priv/legacy/random_resized_crop_var_shape.cu

@@ -193,7 +193,9 @@ __global__ void resize_cubic_v1(const SrcWrapper src, DstWrapper dst, const int
         float fy = (float)((dst_y + 0.5f) * scale_y - 0.5f + top);
         int   sy = cuda::round<cuda::RoundMode::DOWN, int>(fy);
         fy -= sy;
-        sy = cuda::max(1, cuda::min(sy, height - 3));
+        const int syClamped = cuda::max(1, cuda::min(sy, height - 3));
+        fy += static_cast<float>(sy - syClamped);
+        sy = syClamped;
 
         const float A = -0.75f;
 
@@ -208,8 +210,9 @@ __global__ void resize_cubic_v1(const SrcWrapper src, DstWrapper dst, const int
         float fx = (float)((dst_x + 0.5f) * scale_x - 0.5f + left);
         int   sx = cuda::round<cuda::RoundMode::DOWN, int>(fx);
         fx -= sx;
-        fx *= ((sx >= 1) && (sx < width - 3));
-        sx = cuda::max(1, cuda::min(sx, width - 3));
+        const int sxClamped = cuda::max(1, cuda::min(sx, width - 3));
+        fx += static_cast<float>(sx - sxClamped);
+        sx = sxClamped;
 
         float cX[4];
         cX[0] = ((A * (fx + 1.0f) - 5.0f * A) * (fx + 1.0f) + 8.0f * A) * (fx + 1.0f) - 4.0f * A;

src/cvcuda/priv/legacy/resize_var_shape.cu

@@ -188,7 +188,9 @@ __global__ void resize_bicubic(cuda::ImageBatchVarShapeWrap<const T> src, cuda::
         float fy = (float)((dst_y + 0.5f) * scale_y - 0.5f);
         int   sy = cuda::round<cuda::RoundMode::DOWN, int>(fy);
         fy -= sy;
-        sy = cuda::max(1, cuda::min(sy, height - 3));
+        const int syClamped = cuda::max(1, cuda::min(sy, height - 3));
+        fy += static_cast<float>(sy - syClamped); // rebase fractional offset after clamp
+        sy = syClamped;
 
         const float A = -0.75f;
 
@@ -203,8 +205,9 @@ __global__ void resize_bicubic(cuda::ImageBatchVarShapeWrap<const T> src, cuda::
         float fx = (float)((dst_x + 0.5f) * scale_x - 0.5f);
         int   sx = cuda::round<cuda::RoundMode::DOWN, int>(fx);
         fx -= sx;
-        fx *= ((sx >= 1) && (sx < width - 3));
-        sx = cuda::max(1, cuda::min(sx, width - 3));
+        const int sxClamped = cuda::max(1, cuda::min(sx, width - 3));
+        fx += static_cast<float>(sx - sxClamped);
+        sx = sxClamped;
 
         float cX[4];
         cX[0] = ((A * (fx + 1.0f) - 5.0f * A) * (fx + 1.0f) + 8.0f * A) * (fx + 1.0f) - 4.0f * A;