For training and testing, the directory structure is as follows:

|-- datasets
    # test your own imgs
    |-- single

    # train
    |-- DF2K
        |-- HR
        |-- LR_bicubic
            |-- X2
            |-- X3
            |-- X4
    # test
    |-- benchmark
        |-- Set5
            |-- HR
          	|-- LR_bicubic
                |-- X2
                |-- X3
                |-- X4
        |-- Set14
            |-- HR
            |-- LR_bicubic
                |-- X2
                |-- X3
                |-- X4
        |-- B100
            |-- HR
            |-- LR_bicubic
                |-- X2
                |-- X3
                |-- X4
        |-- Urban100
            |-- HR
            |-- LR_bicubic
                |-- X2
                |-- X3
                |-- X4
        |-- Manga109
            |-- HR
            |-- LR_bicubic
                |-- X2
                |-- X3
                |-- X4        

You can download the complete datasets we have collected.