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rcd demosaic: added some comments, #6054

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This commit is contained in:
Ingo Weyrich 2021-01-16 23:32:24 +01:00
parent 59b7eb0bbd
commit 369707df7a
1 changed files with 12 additions and 17 deletions
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29
rtengine/rcd_demosaic.cc
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@ -35,7 +35,7 @@ unsigned fc(const unsigned int cfa[2][2], int r, int c) {
namespace rtengine
{
/**
/*
* RATIO CORRECTED DEMOSAICING
* Luis Sanz Rodriguez (luis.sanz.rodriguez(at)gmail(dot)com)
*
@ -44,7 +44,12 @@ namespace rtengine
* Original code from https://github.com/LuisSR/RCD-Demosaicing
* Licensed under the GNU GPL version 3
*/
// Tiled version by Ingo Weyrich (heckflosse67@gmx.de)
// Luis Sanz Rodriguez significantly optimised the v 2.3 code and simplified the directional
// coefficients in an exact, shorter and more performant formula.
// In cooperation with Hanno Schwalm (hanno@schwalm-bremen.de) and Luis Sanz Rodriguez this has been tuned for performance.
void RawImageSource::rcd_demosaic(size_t chunkSize, bool measure)
{
// Test for RGB cfa
@ -60,7 +65,6 @@ void RawImageSource::rcd_demosaic(size_t chunkSize, bool measure)
}
std::unique_ptr<StopWatch> stop;
if (measure) {
std::cout << "Demosaicing " << W << "x" << H << " image using rcd with " << chunkSize << " tiles per thread" << std::endl;
stop.reset(new StopWatch("rcd demosaic"));
@ -74,8 +78,8 @@ void RawImageSource::rcd_demosaic(size_t chunkSize, bool measure)
}
const unsigned int cfarray[2][2] = {{FC(0,0), FC(0,1)}, {FC(1,0), FC(1,1)}};
constexpr int rcdBorder = 6;
constexpr int tileBorder = 9;
constexpr int tileBorder = 9; // avoid tile-overlap errors
constexpr int rcdBorder = 6; // for the outermost tiles we can have a smaller outer border
constexpr int tileSize = 194;
constexpr int tileSizeN = tileSize - 2 * tileBorder;
const int numTh = H / (tileSizeN) + ((H % (tileSizeN)) ? 1 : 0);
@ -125,9 +129,8 @@ void RawImageSource::rcd_demosaic(size_t chunkSize, bool measure)
cfa[indx] = rgb[c0][indx] = rgb[c1][indx] = LIM01(rawData[row][col] / scale);
}
}
/**
* STEP 1: Find cardinal and diagonal interpolation directions
*/
// Step 1: Find cardinal and diagonal interpolation directions
float bufferV[3][tileSize - 8];
// Step 1.1: Calculate the square of the vertical and horizontal color difference high pass filter
@ -138,7 +141,6 @@ void RawImageSource::rcd_demosaic(size_t chunkSize, bool measure)
}
// Step 1.2: Obtain the vertical and horizontal directional discrimination strength
float bufferH[tileSize - 6] ALIGNED16;
float* V0 = bufferV[0];
float* V1 = bufferV[1];
@ -162,11 +164,7 @@ void RawImageSource::rcd_demosaic(size_t chunkSize, bool measure)
std::swap(V0, V1);
}
/**
* STEP 2: Calculate the low pass filter
*/
// Step 2.1: Low pass filter incorporating green, red and blue local samples from the raw data
// Step 2: Low pass filter incorporating green, red and blue local samples from the raw data
for (int row = 2; row < tileRows - 2; ++row) {
for (int col = 2 + (fc(cfarray, row, 0) & 1), indx = row * tileSize + col, lpindx = indx / 2; col < tilecols - 2; col += 2, indx += 2, ++lpindx) {
lpf[lpindx] = cfa[indx] +
@ -175,10 +173,7 @@ void RawImageSource::rcd_demosaic(size_t chunkSize, bool measure)
}
}
/**
* STEP 3: Populate the green channel
*/
// Step 3.1: Populate the green channel at blue and red CFA positions
// Step 3: Populate the green channel at blue and red CFA positions
for (int row = 4; row < tileRows - 4; ++row) {
for (int col = 4 + (fc(cfarray, row, 0) & 1), indx = row * tileSize + col, lpindx = indx / 2; col < tilecols - 4; col += 2, indx += 2, ++lpindx) {
// Cardinal gradients