static void
interppixel_NDC_clamped (const ImageBuf &buf, float x, float y, float *pixel,
bool envlatlmode)
{
int fx = buf.spec().full_x;
int fy = buf.spec().full_y;
int fw = buf.spec().full_width;
int fh = buf.spec().full_height;
x = static_cast<float>(fx) + x * static_cast<float>(fw);
y = static_cast<float>(fy) + y * static_cast<float>(fh);
const int maxchannels = 64; // Reasonable guess
float p[4][maxchannels];
DASSERT (buf.spec().nchannels <= maxchannels &&
"You need to increase maxchannels");
int n = std::min (buf.spec().nchannels, maxchannels);
x -= 0.5f;
y -= 0.5f;
int xtexel, ytexel;
float xfrac, yfrac;
xfrac = floorfrac (x, &xtexel);
yfrac = floorfrac (y, &ytexel);
// Clamp
int xnext = Imath::clamp (xtexel+1, buf.xmin(), buf.xmax());
int ynext = Imath::clamp (ytexel+1, buf.ymin(), buf.ymax());
xnext = Imath::clamp (xnext, buf.xmin(), buf.xmax());
ynext = Imath::clamp (ynext, buf.ymin(), buf.ymax());
// Get the four texels
buf.getpixel (xtexel, ytexel, p[0], n);
buf.getpixel (xnext, ytexel, p[1], n);
buf.getpixel (xtexel, ynext, p[2], n);
buf.getpixel (xnext, ynext, p[3], n);
if (envlatlmode) {
// For latlong environment maps, in order to conserve energy, we
// must weight the pixels by sin(t*PI) because pixels closer to
// the pole are actually less area on the sphere. Doing this
// wrong will tend to over-represent the high latitudes in
// low-res MIP levels. We fold the area weighting into our
// linear interpolation by adjusting yfrac.
float w0 = (1.0f - yfrac) * sinf ((float)M_PI * (ytexel+0.5f)/(float)fh);
float w1 = yfrac * sinf ((float)M_PI * (ynext+0.5f)/(float)fh);
yfrac = w0 / (w0 + w1);
}
// Bilinearly interpolate
bilerp (p[0], p[1], p[2], p[3], xfrac, yfrac, n, pixel);
}
void
ImageBuf::interppixel (float x, float y, float *pixel) const
{
const int maxchannels = 64; // Reasonable guess
float p[4][maxchannels];
DASSERT (spec().nchannels <= maxchannels &&
"You need to increase maxchannels in ImageBuf::interppixel");
int n = std::min (spec().nchannels, maxchannels);
x -= 0.5f;
y -= 0.5f;
int xtexel, ytexel;
float xfrac, yfrac;
xfrac = floorfrac (x, &xtexel);
yfrac = floorfrac (y, &ytexel);
getpixel (xtexel, ytexel, p[0], n);
getpixel (xtexel+1, ytexel, p[1], n);
getpixel (xtexel, ytexel+1, p[2], n);
getpixel (xtexel+1, ytexel+1, p[3], n);
bilerp (p[0], p[1], p[2], p[3], xfrac, yfrac, n, pixel);
}
static bool
resample_ (ImageBuf &dst, const ImageBuf &src, bool interpolate,
ROI roi, int nthreads)
{
if (nthreads != 1 && roi.npixels() >= 1000) {
// Lots of pixels and request for multi threads? Parallelize.
ImageBufAlgo::parallel_image (
boost::bind(resample_<DSTTYPE,SRCTYPE>, boost::ref(dst),
boost::cref(src), interpolate,
_1 /*roi*/, 1 /*nthreads*/),
roi, nthreads);
return true;
}
// Serial case
const ImageSpec &srcspec (src.spec());
const ImageSpec &dstspec (dst.spec());
int nchannels = src.nchannels();
// Local copies of the source image window, converted to float
float srcfx = srcspec.full_x;
float srcfy = srcspec.full_y;
float srcfw = srcspec.full_width;
float srcfh = srcspec.full_height;
float dstfx = dstspec.full_x;
float dstfy = dstspec.full_y;
float dstfw = dstspec.full_width;
float dstfh = dstspec.full_height;
float dstpixelwidth = 1.0f / dstfw;
float dstpixelheight = 1.0f / dstfh;
float *pel = ALLOCA (float, nchannels);
ImageBuf::Iterator<DSTTYPE> out (dst, roi);
ImageBuf::ConstIterator<SRCTYPE> srcpel (src);
for (int y = roi.ybegin; y < roi.yend; ++y) {
// s,t are NDC space
float t = (y-dstfy+0.5f)*dstpixelheight;
// src_xf, src_xf are image space float coordinates
float src_yf = srcfy + t * srcfh - 0.5f;
// src_x, src_y are image space integer coordinates of the floor
int src_y;
(void) floorfrac (src_yf, &src_y);
for (int x = roi.xbegin; x < roi.xend; ++x) {
float s = (x-dstfx+0.5f)*dstpixelwidth;
float src_xf = srcfx + s * srcfw - 0.5f;
int src_x;
(void) floorfrac (src_xf, &src_x);
if (interpolate) {
src.interppixel (src_xf, src_yf, pel);
for (int c = roi.chbegin; c < roi.chend; ++c)
out[c] = pel[c];
} else {
srcpel.pos (src_x, src_y, 0);
for (int c = roi.chbegin; c < roi.chend; ++c)
out[c] = srcpel[c];
}
++out;
}
}
return true;
}
static bool
resize_ (ImageBuf &dst, const ImageBuf &src,
Filter2D *filter, ROI roi, int nthreads)
{
if (nthreads != 1 && roi.npixels() >= 1000) {
// Lots of pixels and request for multi threads? Parallelize.
ImageBufAlgo::parallel_image (
boost::bind(resize_<DSTTYPE,SRCTYPE>, boost::ref(dst),
boost::cref(src), filter,
_1 /*roi*/, 1 /*nthreads*/),
roi, nthreads);
return true;
}
// Serial case
const ImageSpec &srcspec (src.spec());
const ImageSpec &dstspec (dst.spec());
int nchannels = dstspec.nchannels;
// Local copies of the source image window, converted to float
float srcfx = srcspec.full_x;
float srcfy = srcspec.full_y;
float srcfw = srcspec.full_width;
float srcfh = srcspec.full_height;
// Ratios of dst/src size. Values larger than 1 indicate that we
// are maximizing (enlarging the image), and thus want to smoothly
// interpolate. Values less than 1 indicate that we are minimizing
// (shrinking the image), and thus want to properly filter out the
// high frequencies.
float xratio = float(dstspec.full_width) / srcfw; // 2 upsize, 0.5 downsize
float yratio = float(dstspec.full_height) / srcfh;
float dstfx = dstspec.full_x;
float dstfy = dstspec.full_y;
float dstfw = dstspec.full_width;
float dstfh = dstspec.full_height;
float dstpixelwidth = 1.0f / dstfw;
float dstpixelheight = 1.0f / dstfh;
float *pel = ALLOCA (float, nchannels);
float filterrad = filter->width() / 2.0f;
// radi,radj is the filter radius, as an integer, in source pixels. We
// will filter the source over [x-radi, x+radi] X [y-radj,y+radj].
int radi = (int) ceilf (filterrad/xratio);
int radj = (int) ceilf (filterrad/yratio);
int xtaps = 2*radi + 1;
int ytaps = 2*radj + 1;
bool separable = filter->separable();
float *xfiltval = NULL, *yfiltval = NULL;
if (separable) {
// Allocate temp space to cache the filter weights
xfiltval = ALLOCA (float, xtaps);
yfiltval = ALLOCA (float, ytaps);
}
#if 0
std::cerr << "Resizing " << srcspec.full_width << "x" << srcspec.full_height
<< " to " << dstspec.full_width << "x" << dstspec.full_height << "\n";
std::cerr << "ratios = " << xratio << ", " << yratio << "\n";
std::cerr << "examining src filter support radius of " << radi << " x " << radj << " pixels\n";
std::cerr << "dst range " << roi << "\n";
std::cerr << "separable filter\n";
#endif
// We're going to loop over all output pixels we're interested in.
//
// (s,t) = NDC space coordinates of the output sample we are computing.
// This is the "sample point".
// (src_xf, src_xf) = source pixel space float coordinates of the
// sample we're computing. We want to compute the weighted sum
// of all the source image pixels that fall under the filter when
// centered at that location.
// (src_x, src_y) = image space integer coordinates of the floor,
// i.e., the closest pixel in the source image.
// src_xf_frac and src_yf_frac are the position within that pixel
// of our sample.
ImageBuf::Iterator<DSTTYPE> out (dst, roi);
for (int y = roi.ybegin; y < roi.yend; ++y) {
float t = (y-dstfy+0.5f)*dstpixelheight;
float src_yf = srcfy + t * srcfh;
int src_y;
float src_yf_frac = floorfrac (src_yf, &src_y);
// If using separable filters, our vertical set of filter tap
// weights will be the same for the whole scanline we're on. Just
// compute and normalize them once.
float totalweight_y = 0.0f;
if (separable) {
for (int j = 0; j < ytaps; ++j) {
float w = filter->yfilt (yratio * (j-radj-(src_yf_frac-0.5f)));
yfiltval[j] = w;
totalweight_y += w;
}
for (int i = 0; i <= ytaps; ++i)
yfiltval[i] /= totalweight_y;
}
for (int x = roi.xbegin; x < roi.xend; ++x) {
float s = (x-dstfx+0.5f)*dstpixelwidth;
float src_xf = srcfx + s * srcfw;
int src_x;
float src_xf_frac = floorfrac (src_xf, &src_x);
for (int c = 0; c < nchannels; ++c)
pel[c] = 0.0f;
if (separable) {
// Cache and normalize the horizontal filter tap weights
// just once for this (x,y) position, reuse for all vertical
// taps.
float totalweight_x = 0.0f;
for (int i = 0; i < xtaps; ++i) {
float w = filter->xfilt (xratio * (i-radi-(src_xf_frac-0.5f)));
xfiltval[i] = w;
totalweight_x += w;
}
if (totalweight_x != 0.0f) {
for (int i = 0; i < xtaps; ++i) // normalize x filter
xfiltval[i] /= totalweight_x; // weights
ImageBuf::ConstIterator<SRCTYPE> srcpel (src, src_x-radi, src_x+radi+1,
src_y-radj, src_y+radj+1,
0, 1, ImageBuf::WrapClamp);
for (int j = -radj; j <= radj; ++j) {
float wy = yfiltval[j+radj];
if (wy == 0.0f) {
// 0 weight for this y tap -- move to next line
srcpel.pos (srcpel.x(), srcpel.y()+1, srcpel.z());
continue;
}
for (int i = 0; i < xtaps; ++i, ++srcpel) {
float w = wy * xfiltval[i];
for (int c = 0; c < nchannels; ++c)
pel[c] += w * srcpel[c];
}
}
}
// Copy the pixel value (already normalized) to the output.
DASSERT (out.x() == x && out.y() == y);
if (totalweight_y == 0.0f) {
// zero it out
for (int c = 0; c < nchannels; ++c)
out[c] = 0.0f;
} else {
for (int c = 0; c < nchannels; ++c)
out[c] = pel[c];
}
} else {
// Non-separable
float totalweight = 0.0f;
ImageBuf::ConstIterator<SRCTYPE> srcpel (src, src_x-radi, src_x+radi+1,
src_y-radi, src_y+radi+1,
0, 1, ImageBuf::WrapClamp);
for (int j = -radj; j <= radj; ++j) {
for (int i = -radi; i <= radi; ++i, ++srcpel) {
float w = (*filter)(xratio * (i-(src_xf_frac-0.5f)),
yratio * (j-(src_yf_frac-0.5f)));
totalweight += w;
if (w == 0.0f)
continue;
DASSERT (! srcpel.done());
for (int c = 0; c < nchannels; ++c)
pel[c] += w * srcpel[c];
}
}
DASSERT (srcpel.done());
// Rescale pel to normalize the filter and write it to the
// output image.
DASSERT (out.x() == x && out.y() == y);
if (totalweight == 0.0f) {
// zero it out
for (int c = 0; c < nchannels; ++c)
out[c] = 0.0f;
} else {
for (int c = 0; c < nchannels; ++c)
out[c] = pel[c] / totalweight;
}
}
++out;
}
}
return true;
}
