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Diffstat (limited to 'src/backends/RefWorkloads/ResizeBilinear.cpp')
-rw-r--r-- | src/backends/RefWorkloads/ResizeBilinear.cpp | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/src/backends/RefWorkloads/ResizeBilinear.cpp b/src/backends/RefWorkloads/ResizeBilinear.cpp new file mode 100644 index 0000000000..0bce3c7ed8 --- /dev/null +++ b/src/backends/RefWorkloads/ResizeBilinear.cpp @@ -0,0 +1,92 @@ +// +// Copyright © 2017 Arm Ltd. All rights reserved. +// SPDX-License-Identifier: MIT +// + +#include "ResizeBilinear.hpp" + +#include "TensorBufferArrayView.hpp" + +#include <boost/numeric/conversion/cast.hpp> + +#include <cmath> +#include <algorithm> + +namespace armnn +{ + +namespace +{ + +inline float Lerp(float a, float b, float w) +{ + return w * b + (1.f - w) * a; +} + +} + +void ResizeBilinear(const float* in, const TensorInfo& inputInfo, float* out, const TensorInfo& outputInfo) +{ + // 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. + + const unsigned int batchSize = inputInfo.GetShape()[0]; + const unsigned int channelCount = inputInfo.GetShape()[1]; + + const unsigned int inputHeight = inputInfo.GetShape()[2]; + const unsigned int inputWidth = inputInfo.GetShape()[3]; + const unsigned int outputHeight = outputInfo.GetShape()[2]; + const unsigned int outputWidth = outputInfo.GetShape()[3]; + + // 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) / boost::numeric_cast<float>(outputHeight); + const float scaleX = boost::numeric_cast<float>(inputWidth) / boost::numeric_cast<float>(outputWidth); + + TensorBufferArrayView<const float> input(inputInfo.GetShape(), in); + TensorBufferArrayView<float> output(outputInfo.GetShape(), out); + + for (unsigned int n = 0; n < batchSize; ++n) + { + for (unsigned int c = 0; c < channelCount; ++c) + { + 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; + + // 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); + + // Interpolation weight (range [0,1]). + const float yw = iy - fiy; + + 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); + + // Interpolation weight (range [0,1]). + const float xw = ix - fix; + + // 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); + + // Interpolation + const float ly0 = Lerp(input.Get(n, c, y0, x0), input.Get(n, c, y0, x1), xw); // lerp along row y0. + const float ly1 = Lerp(input.Get(n, c, y1, x0), input.Get(n, c, y1, x1), xw); // lerp along row y1. + const float l = Lerp(ly0, ly1, yw); + + output.Get(n, c, y, x) = l; + } + } + } + } +} + +} //namespace armnn |