/** handy method to display a raster
*
* @param v vector of float
* @returns vector of uint8_t (unisgned char)
*
* distribute as:
* min(v) -> 0
* max(v) -> 255
*/
inline bytes_t raster2bytes(const raster& v) {
auto minmax = std::minmax_element(v.begin(), v.end());
float min = *minmax.first;
float max = *minmax.second;
float diff = max - min;
bytes_t b(v.size());
if (diff == 0) // max == min (useless band)
return b;
float coef = 255.0 / diff;
std::transform(v.begin(), v.end(), b.begin(),
// C++11 lambda, capture local varibles by reference [&]
[&](float f) -> uint8_t { return std::floor( coef * (f - min) ); });
return b;
}
/**
* normalize [0, 1.0] in place
*/
inline raster normalize(raster& v) {
auto minmax = std::minmax_element(v.begin(), v.end());
float min = *minmax.first;
float max = *minmax.second;
float diff = max - min;
if (diff == 0) // max == min
return v;
// normalize in place
for (auto& f : v)
f = (f - min) / diff;
return v;
}