131 lines
3.1 KiB
C++
131 lines
3.1 KiB
C++
|
|
#include <cmath>
|
|
|
|
// Exponential blur, Jani Huhtanen, 2006
|
|
//
|
|
template<int aprec, int zprec>
|
|
static inline void blurinner(unsigned char *bptr, int &zR, int &zG, int &zB, int &zA, int alpha);
|
|
|
|
template<int aprec,int zprec>
|
|
static inline void blurrow( QImage & im, int line, int alpha);
|
|
|
|
template<int aprec, int zprec>
|
|
static inline void blurcol( QImage & im, int col, int alpha);
|
|
|
|
/*
|
|
* expblur(QImage &img, int radius)
|
|
*
|
|
* In-place blur of image 'img' with kernel
|
|
* of approximate radius 'radius'.
|
|
*
|
|
* Blurs with two sided exponential impulse
|
|
* response.
|
|
*
|
|
* aprec = precision of alpha parameter
|
|
* in fixed-point format 0.aprec
|
|
*
|
|
* zprec = precision of state parameters
|
|
* zR,zG,zB and zA in fp format 8.zprec
|
|
*/
|
|
template<int aprec,int zprec>
|
|
void expblur( QImage &img, int radius )
|
|
{
|
|
if(radius<1)
|
|
return;
|
|
|
|
/* Calculate the alpha such that 90% of
|
|
the kernel is within the radius.
|
|
(Kernel extends to infinity)
|
|
*/
|
|
int alpha = (int)((1<<aprec)*(1.0f-expf(-2.3f/(radius+1.f))));
|
|
|
|
for(int row=0;row<img.height();row++)
|
|
{
|
|
blurrow<aprec,zprec>(img,row,alpha);
|
|
}
|
|
|
|
for(int col=0;col<img.width();col++)
|
|
{
|
|
blurcol<aprec,zprec>(img,col,alpha);
|
|
}
|
|
return;
|
|
}
|
|
|
|
template<int aprec, int zprec>
|
|
static inline void blurinner(unsigned char *bptr, int &zR, int &zG, int &zB, int &zA, int alpha)
|
|
{
|
|
int R,G,B,A;
|
|
R = *bptr;
|
|
G = *(bptr+1);
|
|
B = *(bptr+2);
|
|
A = *(bptr+3);
|
|
|
|
zR += (alpha * ((R<<zprec)-zR))>>aprec;
|
|
zG += (alpha * ((G<<zprec)-zG))>>aprec;
|
|
zB += (alpha * ((B<<zprec)-zB))>>aprec;
|
|
zA += (alpha * ((A<<zprec)-zA))>>aprec;
|
|
|
|
*bptr = zR>>zprec;
|
|
*(bptr+1) = zG>>zprec;
|
|
*(bptr+2) = zB>>zprec;
|
|
*(bptr+3) = zA>>zprec;
|
|
}
|
|
|
|
template<int aprec,int zprec>
|
|
static inline void blurrow( QImage & im, int line, int alpha)
|
|
{
|
|
int zR,zG,zB,zA;
|
|
|
|
QRgb *ptr = (QRgb *)im.scanLine(line);
|
|
|
|
zR = *((unsigned char *)ptr )<<zprec;
|
|
zG = *((unsigned char *)ptr + 1)<<zprec;
|
|
zB = *((unsigned char *)ptr + 2)<<zprec;
|
|
zA = *((unsigned char *)ptr + 3)<<zprec;
|
|
|
|
for(int index=1; index<im.width(); index++)
|
|
{
|
|
blurinner<aprec,zprec>((unsigned char *)&ptr[index],zR,zG,zB,zA,alpha);
|
|
}
|
|
for(int index=im.width()-2; index>=0; index--)
|
|
{
|
|
blurinner<aprec,zprec>((unsigned char *)&ptr[index],zR,zG,zB,zA,alpha);
|
|
}
|
|
|
|
|
|
}
|
|
|
|
template<int aprec, int zprec>
|
|
static inline void blurcol( QImage & im, int col, int alpha)
|
|
{
|
|
int zR,zG,zB,zA;
|
|
|
|
QRgb *ptr = (QRgb *)im.bits();
|
|
ptr+=col;
|
|
|
|
zR = *((unsigned char *)ptr )<<zprec;
|
|
zG = *((unsigned char *)ptr + 1)<<zprec;
|
|
zB = *((unsigned char *)ptr + 2)<<zprec;
|
|
zA = *((unsigned char *)ptr + 3)<<zprec;
|
|
|
|
for(int index=im.width(); index<(im.height()-1)*im.width(); index+=im.width())
|
|
{
|
|
blurinner<aprec,zprec>((unsigned char *)&ptr[index],zR,zG,zB,zA,alpha);
|
|
}
|
|
|
|
for(int index=(im.height()-2)*im.width(); index>=0; index-=im.width())
|
|
{
|
|
blurinner<aprec,zprec>((unsigned char *)&ptr[index],zR,zG,zB,zA,alpha);
|
|
}
|
|
|
|
}
|
|
|
|
template<class T>
|
|
inline const T& qClamp(const T &x, const T &low, const T &high)
|
|
{
|
|
if (x < low) return low;
|
|
else if (x > high) return high;
|
|
else return x;
|
|
}
|
|
|