IVGCVSW-4707 - Add AlignCorners and HalfPixelCenters to Resize
* Added AlignCorners and HalfPixelCenters Parameters to Resize
* Added Unit Tests
Signed-off-by: David Monahan <david.monahan@arm.com>
Change-Id: I83420a9bcb7beec9073d201448f64eb53090e1f1
diff --git a/src/backends/reference/workloads/Resize.cpp b/src/backends/reference/workloads/Resize.cpp
index 407774e..16cdd4a 100644
--- a/src/backends/reference/workloads/Resize.cpp
+++ b/src/backends/reference/workloads/Resize.cpp
@@ -30,6 +30,36 @@
return std::sqrt(pow(Xa - boost::numeric_cast<float>(Xb), 2) + pow(Ya - boost::numeric_cast<float>(Yb), 2));
}
+inline float CalculateResizeScale(const unsigned int& InputSize,
+ const unsigned int& OutputSize,
+ const bool& AlignCorners)
+{
+ return (AlignCorners && OutputSize > 1)
+ ? boost::numeric_cast<float>(InputSize - 1) / boost::numeric_cast<float>(OutputSize - 1)
+ : boost::numeric_cast<float>(InputSize) / boost::numeric_cast<float>(OutputSize);
+}
+
+inline float PixelScaler(const unsigned int& Pixel,
+ const float& Scale,
+ const bool& HalfPixelCenters,
+ armnn::ResizeMethod& resizeMethod)
+{
+ // For Half Pixel Centers the Top Left texel is assumed to be at 0.5,0.5
+ if (HalfPixelCenters && resizeMethod == armnn::ResizeMethod::Bilinear)
+ {
+ return (static_cast<float>(Pixel) + 0.5f) * Scale - 0.5f;
+ }
+ // Nearest Neighbour doesn't need to have 0.5f trimmed off as it will floor the values later
+ else if (HalfPixelCenters && resizeMethod == armnn::ResizeMethod::NearestNeighbor)
+ {
+ return (static_cast<float>(Pixel) + 0.5f) * Scale;
+ }
+ else
+ {
+ return static_cast<float>(Pixel) * Scale;
+ }
+}
+
}// anonymous namespace
void Resize(Decoder<float>& in,
@@ -38,8 +68,12 @@
const TensorInfo& outputInfo,
DataLayoutIndexed dataLayout,
armnn::ResizeMethod resizeMethod,
- bool alignCorners)
+ bool alignCorners,
+ bool halfPixelCenters)
{
+ // alignCorners and halfPixelCenters cannot both be true
+ ARMNN_ASSERT(!(alignCorners && halfPixelCenters));
+
// We follow the definition of TensorFlow and AndroidNN: the top-left corner of a texel in the output
// image is projected into the input image to figure out the interpolants and weights. Note that this
// will yield different results than if projecting the centre of output texels.
@@ -52,14 +86,10 @@
const unsigned int outputHeight = outputInfo.GetShape()[dataLayout.GetHeightIndex()];
const unsigned int outputWidth = outputInfo.GetShape()[dataLayout.GetWidthIndex()];
- const unsigned int sizeOffset = resizeMethod == armnn::ResizeMethod::Bilinear && alignCorners ? 1 : 0;
-
// How much to scale pixel coordinates in the output image, to get the corresponding pixel coordinates
// in the input image.
- const float scaleY = boost::numeric_cast<float>(inputHeight - sizeOffset)
- / boost::numeric_cast<float>(outputHeight - sizeOffset);
- const float scaleX = boost::numeric_cast<float>(inputWidth - sizeOffset)
- / boost::numeric_cast<float>(outputWidth - sizeOffset);
+ const float scaleY = CalculateResizeScale(inputHeight, outputHeight, alignCorners);
+ const float scaleX = CalculateResizeScale(inputWidth, outputWidth, alignCorners);
TensorShape inputShape = inputInfo.GetShape();
TensorShape outputShape = outputInfo.GetShape();
@@ -71,11 +101,13 @@
for (unsigned int y = 0; y < outputHeight; ++y)
{
// Corresponding real-valued height coordinate in input image.
- const float iy = boost::numeric_cast<float>(y) * scaleY;
+ float iy = PixelScaler(y, scaleY, halfPixelCenters, resizeMethod);
// Discrete height coordinate of top-left texel (in the 2x2 texel area used for interpolation).
- const float fiy = floorf(iy);
- const unsigned int y0 = boost::numeric_cast<unsigned int>(fiy);
+ const float fiy = (resizeMethod == armnn::ResizeMethod::NearestNeighbor && alignCorners) ?
+ roundf(iy) : floorf(iy);
+ // Pixel scaling a value with Half Pixel Centers can be negative, if so set to 0
+ const unsigned int y0 = static_cast<unsigned int>(std::max(fiy, 0.0f));
// Interpolation weight (range [0,1]).
const float yw = iy - fiy;
@@ -83,16 +115,31 @@
for (unsigned int x = 0; x < outputWidth; ++x)
{
// Real-valued and discrete width coordinates in input image.
- const float ix = boost::numeric_cast<float>(x) * scaleX;
- const float fix = floorf(ix);
- const unsigned int x0 = boost::numeric_cast<unsigned int>(fix);
+ float ix = PixelScaler(x, scaleX, halfPixelCenters, resizeMethod);
+
+ // Nearest Neighbour uses rounding to align to corners
+ const float fix = resizeMethod == armnn::ResizeMethod::NearestNeighbor && alignCorners ?
+ roundf(ix) : floorf(ix);
+ // Pixel scaling a value with Half Pixel Centers can be negative, if so set to 0
+ const unsigned int x0 = static_cast<unsigned int>(std::max(fix, 0.0f));
// Interpolation weight (range [0,1]).
const float xw = ix - fix;
+ unsigned int x1;
+ unsigned int y1;
+ // Half Pixel Centers uses the scaling to compute a weighted parameter for nearby pixels
+ if (halfPixelCenters)
+ {
+ x1 = std::min(static_cast<unsigned int>(std::ceil(ix)), inputWidth - 1u);
+ y1 = std::min(static_cast<unsigned int>(std::ceil(iy)), inputHeight - 1u);
+ }
// Discrete width/height coordinates of texels below and to the right of (x0, y0).
- const unsigned int x1 = std::min(x0 + 1, inputWidth - 1u);
- const unsigned int y1 = std::min(y0 + 1, inputHeight - 1u);
+ else
+ {
+ x1 = std::min(x0 + 1, inputWidth - 1u);
+ y1 = std::min(y0 + 1, inputHeight - 1u);
+ }
float interpolatedValue;
switch (resizeMethod)