4.3 Linear transformations in the Euclidean plane
We have just seen that a linear transformation can be described by the image of a basis set. From a geometric viewpoint, they are functions mapping parallelepipeds to parallelepipeds.
Because of the linearity, you can imagine this as distorting the grid determined by the bases.
In two dimensions, we have seen a few examples of geometric maps such as scaling and rotation as linear transformations. Now we can put them into matrix form. There are five of them in particular that we will study: stretching, shearing, rotation, reflection, and projection.
These simple transformations are not only essential to build intuition, but they are also frequently applied in computer vision. Flipping, rotating, and stretching are essential parts of image augmentation pipelines, greatly enhancing the performance of models.
4.3.1 Stretching
The simplest one is...