The following File Exchange link provides code for slantlet transformation: https://www.mathworks.com/matlabcentral/fileexchange/41333-simulation-of-dct-walsh-hadamard-haar-and-slant-transform-using-variable-block-sizes
You can refer to the following MATLAB answer thread for more details on a similar question: https://www.mathworks.com/matlabcentral/answers/353003-how-can-i-implement-the-slantlet-transform-for-2d-image
