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/* Copyright (c) 2022, NVIDIA CORPORATION. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of NVIDIA CORPORATION nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "common.h"
///////////////////////////////////////////////////////////////////////////////
/// \brief downscale image
///
/// CUDA kernel, relies heavily on texture unit
/// \param[in] width image width
/// \param[in] height image height
/// \param[in] stride image stride
/// \param[out] out result
///////////////////////////////////////////////////////////////////////////////
__global__ void DownscaleKernel(int width, int height, int stride, float *out,
cudaTextureObject_t texFine) {
const int ix = threadIdx.x + blockIdx.x * blockDim.x;
const int iy = threadIdx.y + blockIdx.y * blockDim.y;
if (ix >= width || iy >= height) {
return;
}
float dx = 1.0f / (float)width;
float dy = 1.0f / (float)height;
float x = ((float)ix + 0.5f) * dx;
float y = ((float)iy + 0.5f) * dy;
out[ix + iy * stride] = 0.25f * (tex2D<float>(texFine, x - dx * 0.25f, y) +
tex2D<float>(texFine, x + dx * 0.25f, y) +
tex2D<float>(texFine, x, y - dy * 0.25f) +
tex2D<float>(texFine, x, y + dy * 0.25f));
}
///////////////////////////////////////////////////////////////////////////////
/// \brief downscale image
///
/// \param[in] src image to downscale
/// \param[in] width image width
/// \param[in] height image height
/// \param[in] stride image stride
/// \param[out] out result
///////////////////////////////////////////////////////////////////////////////
static void Downscale(const float *src, int width, int height, int stride,
int newWidth, int newHeight, int newStride, float *out) {
dim3 threads(32, 8);
dim3 blocks(iDivUp(newWidth, threads.x), iDivUp(newHeight, threads.y));
cudaTextureObject_t texFine;
cudaResourceDesc texRes;
memset(&texRes, 0, sizeof(cudaResourceDesc));
texRes.resType = cudaResourceTypePitch2D;
texRes.res.pitch2D.devPtr = (void *)src;
texRes.res.pitch2D.desc = cudaCreateChannelDesc<float>();
texRes.res.pitch2D.width = width;
texRes.res.pitch2D.height = height;
texRes.res.pitch2D.pitchInBytes = stride * sizeof(float);
cudaTextureDesc texDescr;
memset(&texDescr, 0, sizeof(cudaTextureDesc));
texDescr.normalizedCoords = true;
texDescr.filterMode = cudaFilterModeLinear;
texDescr.addressMode[0] = cudaAddressModeMirror;
texDescr.addressMode[1] = cudaAddressModeMirror;
texDescr.readMode = cudaReadModeElementType;
checkCudaErrors(cudaCreateTextureObject(&texFine, &texRes, &texDescr, NULL));
DownscaleKernel<<<blocks, threads>>>(newWidth, newHeight, newStride, out,
texFine);
}
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