double CropTransformer::ApplyRatioJitter(const double minVal, const double maxVal, std::mt19937 &rng)
{
assert(minVal > 0 && minVal <= maxVal); // ratio should always be > 0
switch (m_jitterType)
{
case RatioJitterType::None:
return minVal;
case RatioJitterType::UniRatio:
if (minVal == maxVal)
return minVal;
else
return UniRealT(minVal, maxVal)(rng);
default:
RuntimeError("Jitter type currently not implemented.");
}
return -1;
}
void CropTransformer::Apply(cv::Mat &mat)
{
auto seed = GetSeed();
auto rng = m_rngs.pop_or_create(
[seed]()
{
return std::make_unique<std::mt19937>(seed);
});
double ratio = 1;
switch (m_jitterType)
{
case RatioJitterType::None:
ratio = m_cropRatioMin;
break;
case RatioJitterType::UniRatio:
if (m_cropRatioMin == m_cropRatioMax)
{
ratio = m_cropRatioMin;
}
else
{
ratio = UniRealT(m_cropRatioMin, m_cropRatioMax)(*rng);
assert(m_cropRatioMin <= ratio && ratio < m_cropRatioMax);
}
break;
default:
RuntimeError("Jitter type currently not implemented.");
}
mat = mat(GetCropRect(m_cropType, mat.rows, mat.cols, ratio, *rng));
if (m_hFlip && std::bernoulli_distribution()(*rng))
{
cv::flip(mat, mat, 1);
}
m_rngs.push(std::move(rng));
}
cv::Rect CropTransformer::GetCropRect(CropType type, int viewIndex, int crow, int ccol,
double cropRatio, std::mt19937 &rng)
{
assert(crow > 0);
assert(ccol > 0);
assert(0 < cropRatio && cropRatio <= 1.0);
// Get square crop size that preserves aspect ratio.
int cropSize = (int)(std::min(crow, ccol) * cropRatio);
int cropSizeX = cropSize;
int cropSizeY = cropSize;
// Change aspect ratio, if this option is enabled.
if (m_curAspectRatioRadius > 0)
{
double factor = 1.0 + UniRealT(-m_curAspectRatioRadius, m_curAspectRatioRadius)(rng);
double area = cropSize * cropSize;
double newArea = area * factor;
if (std::bernoulli_distribution()(rng))
{
cropSizeX = (int)std::sqrt(newArea);
cropSizeY = (int)(area / cropSizeX);
}
else
{
cropSizeY = (int)std::sqrt(newArea);
cropSizeX = (int)(area / cropSizeY);
}
// This clamping should be ok if jittering ratio is not too big.
cropSizeX = std::min(cropSizeX, ccol);
cropSizeY = std::min(cropSizeY, crow);
}
int xOff = -1;
int yOff = -1;
switch (type)
{
case CropType::Center:
assert(viewIndex == 0);
xOff = (ccol - cropSizeX) / 2;
yOff = (crow - cropSizeY) / 2;
break;
case CropType::Random:
assert(viewIndex == 0);
xOff = UniIntT(0, ccol - cropSizeX)(rng);
yOff = UniIntT(0, crow - cropSizeY)(rng);
break;
case CropType::MultiView10:
{
assert(0 <= viewIndex && viewIndex < 10);
// 0 - 4: 4 corners + center crop. 5 - 9: same, but with a flip.
int isubView = viewIndex % 5;
switch (isubView)
{
// top-left
case 0:
xOff = 0;
yOff = 0;
break;
// top-right
case 1:
xOff = ccol - cropSizeX;
yOff = 0;
break;
// bottom-left
case 2:
xOff = 0;
yOff = crow - cropSizeY;
break;
// bottom-right
case 3:
xOff = ccol - cropSizeX;
yOff = crow - cropSizeY;
break;
// center
case 4:
xOff = (ccol - cropSizeX) / 2;
yOff = (crow - cropSizeY) / 2;
break;
}
break;
}
default:
assert(false);
}
assert(0 <= xOff && xOff <= ccol - cropSizeX);
assert(0 <= yOff && yOff <= crow - cropSizeY);
return cv::Rect(xOff, yOff, cropSizeX, cropSizeY);
}