Open CV Mat

• Mat::empty needed

• Save
• vector field
• point cloud
• histogram
• ... usually 2d video data

• mat(vector) return 1 col → need to .t

• MatExpr

What is the purpose of cv::MatExpr?

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https://stackoverflow.com/questions/39964583/what-is-the-purpose-of-cvmatexpr

Create

• eye

• one

• zero

• create, setTo (init)

Copy

• copyTo, clone is deep copy

Get

• roi(region of interest) = Rect or (rowRange, colRange)

• colRange - shallow

• rowRange- shallow

• row - shallow

• col - shallow

Pixel

• at<uchar>(y, x) - Slow

• ptr<>(y) return start pointer uchar* can access by p[i] - Faster

• MatIterator - Slow
• mat::begin() - first pixel location
• mat::end() - next of final pixel location

Normalization

• convertTo - data by alpha and beta

• reshape - new row or or channel

• resize - new row and initialize

• pop_back - nelem remove row count

Data

• Scalar sum

• Scalar mean

• minMAxLoc(ation)