/* 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.
*/
////////////////////////////////////////////////////////////////////////////////
// NLM kernel
////////////////////////////////////////////////////////////////////////////////
__global__ void NLM(TColor *dst, int imageW, int imageH, float Noise,
float lerpC, cudaTextureObject_t texImage) {
const int ix = blockDim.x * blockIdx.x + threadIdx.x;
const int iy = blockDim.y * blockIdx.y + threadIdx.y;
// Add half of a texel to always address exact texel centers
const float x = (float)ix + 0.5f;
const float y = (float)iy + 0.5f;
if (ix < imageW && iy < imageH) {
// Normalized counter for the NLM weight threshold
float fCount = 0;
// Total sum of pixel weights
float sumWeights = 0;
// Result accumulator
float3 clr = {0, 0, 0};
// Cycle through NLM window, surrounding (x, y) texel
for (float i = -NLM_WINDOW_RADIUS; i <= NLM_WINDOW_RADIUS; i++)
for (float j = -NLM_WINDOW_RADIUS; j <= NLM_WINDOW_RADIUS; j++) {
// Find color distance from (x, y) to (x + j, y + i)
float weightIJ = 0;
for (float n = -NLM_BLOCK_RADIUS; n <= NLM_BLOCK_RADIUS; n++)
for (float m = -NLM_BLOCK_RADIUS; m <= NLM_BLOCK_RADIUS; m++)
weightIJ += vecLen(tex2D<float4>(texImage, x + j + m, y + i + n),
tex2D<float4>(texImage, x + m, y + n));
// Derive final weight from color and geometric distance
weightIJ =
__expf(-(weightIJ * Noise + (i * i + j * j) * INV_NLM_WINDOW_AREA));
// Accumulate (x + j, y + i) texel color with computed weight
float4 clrIJ = tex2D<float4>(texImage, x + j, y + i);
clr.x += clrIJ.x * weightIJ;
clr.y += clrIJ.y * weightIJ;
clr.z += clrIJ.z * weightIJ;
// Sum of weights for color normalization to [0..1] range
sumWeights += weightIJ;
// Update weight counter, if NLM weight for current window texel
// exceeds the weight threshold
fCount += (weightIJ > NLM_WEIGHT_THRESHOLD) ? INV_NLM_WINDOW_AREA : 0;
}
// Normalize result color by sum of weights
sumWeights = 1.0f / sumWeights;
clr.x *= sumWeights;
clr.y *= sumWeights;
clr.z *= sumWeights;
// Choose LERP quotient basing on how many texels
// within the NLM window exceeded the weight threshold
float lerpQ = (fCount > NLM_LERP_THRESHOLD) ? lerpC : 1.0f - lerpC;
// Write final result to global memory
float4 clr00 = tex2D<float4>(texImage, x, y);
clr.x = lerpf(clr.x, clr00.x, lerpQ);
clr.y = lerpf(clr.y, clr00.y, lerpQ);
clr.z = lerpf(clr.z, clr00.z, lerpQ);
dst[imageW * iy + ix] = make_color(clr.x, clr.y, clr.z, 0);
}
}
extern "C" void cuda_NLM(TColor *d_dst, int imageW, int imageH, float Noise,
float lerpC, cudaTextureObject_t texImage) {
dim3 threads(BLOCKDIM_X, BLOCKDIM_Y);
dim3 grid(iDivUp(imageW, BLOCKDIM_X), iDivUp(imageH, BLOCKDIM_Y));
NLM<<<grid, threads>>>(d_dst, imageW, imageH, Noise, lerpC, texImage);
}
////////////////////////////////////////////////////////////////////////////////
// Stripped NLM kernel, only highlighting areas with different LERP directions
////////////////////////////////////////////////////////////////////////////////
__global__ void NLMdiag(TColor *dst, unsigned int imageW, unsigned int imageH,
float Noise, float lerpC,
cudaTextureObject_t texImage) {
const int ix = blockDim.x * blockIdx.x + threadIdx.x;
const int iy = blockDim.y * blockIdx.y + threadIdx.y;
// Add half of a texel to always address exact texel centers
const float x = (float)ix + 0.5f;
const float y = (float)iy + 0.5f;
if (ix < imageW && iy < imageH) {
// Normalized counter for the weight threshold
float fCount = 0;
// Cycle through NLM window, surrounding (x, y) texel
for (float i = -NLM_WINDOW_RADIUS; i <= NLM_WINDOW_RADIUS; i++)
for (float j = -NLM_WINDOW_RADIUS; j <= NLM_WINDOW_RADIUS; j++) {
// Find color distance between (x, y) and (x + j, y + i)
float weightIJ = 0;
for (float n = -NLM_BLOCK_RADIUS; n <= NLM_BLOCK_RADIUS; n++)
for (float m = -NLM_BLOCK_RADIUS; m <= NLM_BLOCK_RADIUS; m++)
weightIJ += vecLen(tex2D<float4>(texImage, x + j + m, y + i + n),
tex2D<float4>(texImage, x + m, y + n));
// Derive final weight from color and geometric distance
weightIJ =
__expf(-(weightIJ * Noise + (i * i + j * j) * INV_NLM_WINDOW_AREA));
// Increase the weight threshold counter
fCount += (weightIJ > NLM_WEIGHT_THRESHOLD) ? INV_NLM_WINDOW_AREA : 0;
}
// Choose LERP quotient basing on how many texels
// within the NLM window exceeded the LERP threshold
float lerpQ = (fCount > NLM_LERP_THRESHOLD) ? 1.0f : 0;
// Write final result to global memory
dst[imageW * iy + ix] = make_color(lerpQ, 0, (1.0f - lerpQ), 0);
};
}
extern "C" void cuda_NLMdiag(TColor *d_dst, int imageW, int imageH, float Noise,
float lerpC, cudaTextureObject_t texImage) {
dim3 threads(BLOCKDIM_X, BLOCKDIM_Y);
dim3 grid(iDivUp(imageW, BLOCKDIM_X), iDivUp(imageH, BLOCKDIM_Y));
NLMdiag<<<grid, threads>>>(d_dst, imageW, imageH, Noise, lerpC, texImage);
}