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Move the intensity calculation to the Pixel class...

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This commit is contained in:
Pavel Krajcevski 2013-10-01 18:03:59 -04:00
parent ce7bb8e891
commit 0112f2cca7
3 changed files with 22 additions and 15 deletions
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18
PVRTCEncoder/src/Image.cpp
View File

@ -73,11 +73,6 @@ inline T Clamp(const T &v, const T &a, const T &b) {
return ::std::min(::std::max(a, v), b);
}
static float ConvertChannelToFloat(uint8 channel, uint8 bitDepth) {
float denominator = static_cast<float>((1 << bitDepth) - 1);
return static_cast<float>(channel) / denominator;
}
namespace PVRTCC {
Image::Image(uint32 height, uint32 width)
@ -280,14 +275,7 @@ void Image::ContentAwareDownscale(uint32 xtimes, uint32 ytimes,
// Then, compute the intensity of the image
for(uint32 i = 0; i < w * h; i++) {
// First convert the pixel values to floats using
// premultiplied alpha...
float a = ConvertChannelToFloat(m_Pixels[i].A(), bitDepth[0]);
float r = a * ConvertChannelToFloat(m_Pixels[i].R(), bitDepth[1]);
float g = a * ConvertChannelToFloat(m_Pixels[i].G(), bitDepth[2]);
float b = a * ConvertChannelToFloat(m_Pixels[i].B(), bitDepth[3]);
I[i] = r * 0.21f + g * 0.71f + b * 0.07f;
I[i] = m_Pixels[i].ToIntensity();
}
// Use central differences to calculate Ix, Iy, Ixx, Iyy...
@ -308,7 +296,7 @@ void Image::ContentAwareDownscale(uint32 xtimes, uint32 ytimes,
Iy[idx] = (I[yphidx] - I[ymhidx]) / 2.0f;
for(uint32 c = 0; c <= 3; c++) {
#define CPNT(dx) ConvertChannelToFloat(m_Pixels[dx].Component(c), bitDepth[c])
#define CPNT(dx) Pixel::ConvertChannelToFloat(m_Pixels[dx].Component(c), bitDepth[c])
Ix[c][idx] = (CPNT(xphidx) - CPNT(xmhidx)) / 2.0f;
Ixx[c][idx] = (CPNT(xphidx) - 2.0f*CPNT(idx) + CPNT(xmhidx)) / 2.0f;
Iyy[c][idx] = (CPNT(yphidx) - 2.0f*CPNT(idx) + CPNT(ymhidx)) / 2.0f;
@ -349,7 +337,7 @@ void Image::ContentAwareDownscale(uint32 xtimes, uint32 ytimes,
float denom = Ixsq + Iysq;
for(uint32 c = 0; c < 4; c++) {
float I0 = ConvertChannelToFloat(current.Component(c), bitDepth[c]);
float I0 = Pixel::ConvertChannelToFloat(current.Component(c), bitDepth[c]);
float It = Ixx[c][idx] + Iyy[c][idx];
if(fabs(denom) > 1e-6) {
It -= (Ixsq * Ixx[c][idx] +

9
PVRTCEncoder/src/Pixel.cpp
View File

@ -190,6 +190,15 @@ namespace PVRTCC {
}
}
float Pixel::ToIntensity() const {
// First convert the pixel values to floats using premultiplied alpha...
float a = ConvertChannelToFloat(A(), m_BitDepth[0]);
float r = a * ConvertChannelToFloat(R(), m_BitDepth[1]);
float g = a * ConvertChannelToFloat(G(), m_BitDepth[2]);
float b = a * ConvertChannelToFloat(B(), m_BitDepth[3]);
return r * 0.21f + g * 0.71f + b * 0.07f;
}
uint32 Pixel::PackRGBA() const {
Pixel eightBit(*this);
const uint8 eightBitDepth[4] = { 8, 8, 8, 8 };

10
PVRTCEncoder/src/Pixel.h
View File

@ -96,6 +96,16 @@ class Pixel {
// smaller to larger bit depths.
void ChangeBitDepth(const uint8 (&newDepth)[4]);
static float ConvertChannelToFloat(uint8 channel, uint8 bitDepth) {
float denominator = static_cast<float>((1 << bitDepth) - 1);
return static_cast<float>(channel) / denominator;
}
// Returns the intensity of the pixel. Computed using the following
// formula:
// a*r*0.21f + a*g*0.71f + a*b*0.07f;
float ToIntensity() const;
// Changes the bit depth of a single component. See the comment
// above for how we do this.
static uint8 ChangeBitDepth(uint8 val, uint8 oldDepth, uint8 newDepth);