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Fix alpha-weighted filtering.

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This commit is contained in:
castano 2009-01-28 12:10:04 +00:00
parent 242aa4254e
commit 1afdf2da8a
2 changed files with 22 additions and 20 deletions
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38
src/nvimage/FloatImage.cpp
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@ -12,9 +12,6 @@
#include <math.h>
// This value is to prevent division by zero when weighting kernels by alpha.
#define ALPHA_EPSILON (1.0f / 256.0f)
using namespace nv;
@ -710,7 +707,12 @@ FloatImage * FloatImage::resize(const Filter & filter, uint w, uint h, WrapMode
for (uint y = 0; y < m_height; y++) {
this->applyKernelHorizontal(xkernel, y, c, alpha, wm, tmp_channel + y * w);
}
}
// Process all channels before applying vertical kernel to make sure alpha has been computed.
for (uint c = 0; c < m_componentNum; c++)
{
float * dst_channel = dst_image->channel(c);
for (uint x = 0; x < w; x++) {
@ -803,7 +805,7 @@ float FloatImage::applyKernelHorizontal(const Kernel1 * k, int x, int y, uint c,
/// Apply 1D vertical kernel at the given coordinates and return result.
void FloatImage::applyKernelVertical(const PolyphaseKernel & k, int x, uint c, WrapMode wm, float * output) const
void FloatImage::applyKernelVertical(const PolyphaseKernel & k, int x, uint c, WrapMode wm, float * __restrict output) const
{
const uint length = k.length();
const float scale = float(length) / float(m_height);
@ -835,7 +837,7 @@ void FloatImage::applyKernelVertical(const PolyphaseKernel & k, int x, uint c, W
}
/// Apply 1D horizontal kernel at the given coordinates and return result.
void FloatImage::applyKernelHorizontal(const PolyphaseKernel & k, int y, uint c, WrapMode wm, float * output) const
void FloatImage::applyKernelHorizontal(const PolyphaseKernel & k, int y, uint c, WrapMode wm, float * __restrict output) const
{
const uint length = k.length();
const float scale = float(length) / float(m_width);
@ -868,7 +870,7 @@ void FloatImage::applyKernelHorizontal(const PolyphaseKernel & k, int y, uint c,
/// Apply 1D vertical kernel at the given coordinates and return result.
void FloatImage::applyKernelVertical(const PolyphaseKernel & k, int x, uint c, uint a, WrapMode wm, float * output) const
void FloatImage::applyKernelVertical(const PolyphaseKernel & k, int x, uint c, uint a, WrapMode wm, float * __restrict output) const
{
const uint length = k.length();
const float scale = float(length) / float(m_height);
@ -888,23 +890,23 @@ void FloatImage::applyKernelVertical(const PolyphaseKernel & k, int x, uint c, u
const int right = (int)ceilf(center + width);
nvCheck(right - left <= windowSize);
float alphaSum = 0;
float norm = 0;
float sum = 0;
for (int j = 0; j < windowSize; ++j)
{
const int idx = this->index(x, j+left, wm);
float alphaFactor = alpha[idx] + ALPHA_EPSILON;
alphaSum += alphaFactor;
sum += k.valueAt(i, j) * channel[idx] * alphaFactor;
float w = k.valueAt(i, j) * (alpha[idx] + (1.0f / 256.0f));
norm += w;
sum += w * channel[idx];
}
output[i] = sum / alphaSum;
output[i] = sum / norm;
}
}
/// Apply 1D horizontal kernel at the given coordinates and return result.
void FloatImage::applyKernelHorizontal(const PolyphaseKernel & k, int y, uint c, uint a, WrapMode wm, float * output) const
void FloatImage::applyKernelHorizontal(const PolyphaseKernel & k, int y, uint c, uint a, WrapMode wm, float * __restrict output) const
{
const uint length = k.length();
const float scale = float(length) / float(m_width);
@ -924,18 +926,18 @@ void FloatImage::applyKernelHorizontal(const PolyphaseKernel & k, int y, uint c,
const int right = (int)ceilf(center + width);
nvDebugCheck(right - left <= windowSize);
float alphaSum = 0.0f;
float norm = 0.0f;
float sum = 0;
for (int j = 0; j < windowSize; ++j)
{
const int idx = this->index(left + j, y, wm);
float alphaFactor = alpha[idx] + ALPHA_EPSILON;
alphaSum += alphaFactor;
sum += k.valueAt(i, j) * channel[idx] * alphaFactor;
float w = k.valueAt(i, j) * (alpha[idx] + (1.0f / 256.0f));
norm += w;
sum += w * channel[idx];
}
output[i] = sum / alphaSum;
output[i] = sum / norm;
}
}

4
src/nvimage/FloatImage.h
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@ -73,9 +73,9 @@ public:
NVIMAGE_API FloatImage * fastDownSample() const;
NVIMAGE_API FloatImage * downSample(const Filter & filter, WrapMode wm) const;
NVIMAGE_API FloatImage * downSample(const Filter & filter, WrapMode wm, uint alpha) const;
NVIMAGE_API FloatImage * downSample(const Filter & filter, WrapMode wm, uint alpha) const;
NVIMAGE_API FloatImage * resize(const Filter & filter, uint w, uint h, WrapMode wm) const;
NVIMAGE_API FloatImage * resize(const Filter & filter, uint w, uint h, WrapMode wm, uint alpha) const;
NVIMAGE_API FloatImage * resize(const Filter & filter, uint w, uint h, WrapMode wm, uint alpha) const;
//NVIMAGE_API FloatImage * downSample(const Kernel1 & filter, WrapMode wm) const;
//NVIMAGE_API FloatImage * downSample(const Kernel1 & filter, uint w, uint h, WrapMode wm) const;