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Correctly apply LCP "distortion" correction for Fisheye lenses

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Note: as discussed e.g. at http://lensfun.sourceforge.net/manual/corrections.html, this is really a combination of distortion correction and change of projection (from fisheye to rectilinear), but "distortion correction" is how the Adobe camera model calls it, and this is how it appears in the RT gui
This commit is contained in:
Alberto Griggio
2017-04-08 10:13:53 +02:00
parent 73e14702dd
commit 871c75e494
3 changed files with 65 additions and 26 deletions
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38
rtengine/iptransform.cc
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@@ -85,16 +85,17 @@ float normn (float a, float b, int n)
}
}
void correct_distortion (const rtengine::LCPMapper *lcp, double &x, double &y,
int cx, int cy)
void correct_distortion(const rtengine::LCPMapper *lcp, double &x, double &y,
int cx, int cy, double scale)
{
assert (lcp);
x += cx;
y += cy;
lcp->correctDistortion (x, y);
x -= cx;
y -= cy;
lcp->correctDistortion(x, y, scale);
x -= (cx * scale);
y -= (cy * scale);
}
}
@@ -156,11 +157,14 @@ bool ImProcFunctions::transCoord (int W, int H, const std::vector<Coord2D> &src,
double x_d = src[i].x, y_d = src[i].y;
if (pLCPMap && params->lensProf.useDist) {
correct_distortion (pLCPMap, x_d, y_d, 0, 0);
correct_distortion (pLCPMap, x_d, y_d, 0, 0, ascale);
} else {
x_d *= ascale;
y_d *= ascale;
}
y_d = ascale * (y_d - h2);
x_d = ascale * (x_d - w2);
x_d += ascale * (0 - w2); // centering x coord & scale
y_d += ascale * (0 - h2); // centering y coord & scale
if (needsPerspective()) {
// horizontal perspective transformation
@@ -799,11 +803,14 @@ void ImProcFunctions::transformHighQuality (Imagefloat* original, Imagefloat* tr
double x_d = x, y_d = y;
if (enableLCPDist) {
correct_distortion (pLCPMap, x_d, y_d, cx, cy); // must be first transform
correct_distortion(pLCPMap, x_d, y_d, cx, cy, ascale); // must be first transform
} else {
x_d *= ascale;
y_d *= ascale;
}
x_d = ascale * (x_d + cx - w2); // centering x coord & scale
y_d = ascale * (y_d + cy - h2); // centering y coord & scale
x_d += ascale * (cx - w2); // centering x coord & scale
y_d += ascale * (cy - h2); // centering y coord & scale
double vig_x_d = 0., vig_y_d = 0.;
@@ -976,11 +983,14 @@ void ImProcFunctions::transformPreview (Imagefloat* original, Imagefloat* transf
double x_d = x, y_d = y;
if (pLCPMap && params->lensProf.useDist) {
correct_distortion (pLCPMap, x_d, y_d, cx, cy); // must be first transform
correct_distortion(pLCPMap, x_d, y_d, cx, cy, ascale); // must be first transform
} else {
x_d *= ascale;
y_d *= ascale;
}
y_d = ascale * (y_d + cy - h2); // centering y coord & scale
x_d = ascale * (x_d + cx - w2); // centering x coord & scale
x_d += ascale * (cx - w2); // centering x coord & scale
y_d += ascale * (cy - h2); // centering y coord & scale
double vig_x_d = 0., vig_y_d = 0.;

50
rtengine/lcp.cc
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@@ -198,24 +198,52 @@ LCPMapper::LCPMapper(LCPProfile* pProf, float focalLength, float focalLength35mm
}
enableCA = !vignette && focusDist > 0;
isFisheye = pProf->isFisheye;
}
void LCPMapper::correctDistortion(double& x, double& y) const
void LCPMapper::correctDistortion(double& x, double& y, double scale) const
{
double xd = (x - mc.x0) / mc.fx, yd = (y - mc.y0) / mc.fy;
if (isFisheye) {
double u = x * scale;
double v = y * scale;
double u0 = mc.x0 * scale;
double v0 = mc.y0 * scale;
double du = (u - u0);
double dv = (v - v0);
double fx = mc.fx;
double fy = mc.fy;
double k1 = mc.param[0];
double k2 = mc.param[1];
double r = sqrt(du * du + dv * dv);
double f = sqrt(fx*fy / (scale * scale));
double th = atan2(r, f);
double th2 = th * th;
double cfact = (((k2 * th2 + k1) * th2 + 1) * th) / r;
double ud = cfact * fx * du + u0;
double vd = cfact * fy * dv + v0;
const LCPModelCommon::Param aDist = mc.param;
double rsqr = xd * xd + yd * yd;
double xfac = aDist[swapXY ? 3 : 4], yfac = aDist[swapXY ? 4 : 3];
x = ud;
y = vd;
} else {
x *= scale;
y *= scale;
double x0 = mc.x0 * scale;
double y0 = mc.y0 * scale;
double xd = (x - x0) / mc.fx, yd = (y - y0) / mc.fy;
double commonFac = (((aDist[2] * rsqr + aDist[1]) * rsqr + aDist[0]) * rsqr + 1.)
+ 2. * (yfac * yd + xfac * xd);
const LCPModelCommon::Param aDist = mc.param;
double rsqr = xd * xd + yd * yd;
double xfac = aDist[swapXY ? 3 : 4], yfac = aDist[swapXY ? 4 : 3];
double xnew = xd * commonFac + xfac * rsqr;
double ynew = yd * commonFac + yfac * rsqr;
double commonFac = (((aDist[2] * rsqr + aDist[1]) * rsqr + aDist[0]) * rsqr + 1.)
+ 2. * (yfac * yd + xfac * xd);
x = xnew * mc.fx + mc.x0;
y = ynew * mc.fy + mc.y0;
double xnew = xd * commonFac + xfac * rsqr;
double ynew = yd * commonFac + yfac * rsqr;
x = xnew * mc.fx + x0;
y = ynew * mc.fy + y0;
}
}
void LCPMapper::correctCA(double& x, double& y, int channel) const

3
rtengine/lcp.h
View File

@@ -142,6 +142,7 @@ class LCPMapper
bool swapXY;
LCPModelCommon mc;
LCPModelCommon chrom[3]; // in order RedGreen/Green/BlueGreen
bool isFisheye;
public:
bool enableCA; // is the mapper capable if CA correction?
@@ -150,7 +151,7 @@ public:
LCPMapper(LCPProfile* pProf, float focalLength, float focalLength35mm, float focusDist, float aperture, bool vignette, bool useCADistP, int fullWidth, int fullHeight,
const CoarseTransformParams& coarse, int rawRotationDeg);
void correctDistortion(double& x, double& y) const; // MUST be the first stage
void correctDistortion(double& x, double& y, double scale) const; // MUST be the first stage
void correctCA(double& x, double& y, int channel) const;
void processVignetteLine(int width, int y, float *line) const;
void processVignetteLine3Channels(int width, int y, float *line) const;