The image_transform function uses file ../images/epyc.jpg as a test image by default. A different file named image_file may be specified when invoking the function in MATLAB.
>> image_transform('image_file')
Default output resolution in pixels is 1024 $\times$ 1024. A different resolution of $x_{res} \times y_{res}$ may be specified by invoking
>> image_transform('image_file', [ xres yres ])
The image_transform function reads the test image file, performs a sequence of linear transformations on image pixel coordinates, and stores these transformations in a file named bli_coords.mat along with the test image pixel array. When this function is executed in MATLAB, a sequence of image transformations are displayed.