Put datasets here as ./datasets/DIV2K/HR/0801.png.

Note: there are two ways to test the model. First, use GT mode to load data and generate HR-LR image pairs on-the-fly. Second, generating all testing sets at one time and use GTLQ mode to load data. Testing sets used in the paper can be generated by

python prepare_testset.py --opt options/test/prepare_testset.yml

For spatially invariant (SI) SR, HR and LR images are put in HR_si and LR_mode0_noise0, respectively. For spatially variant (SV) SR, HR and LR images are organized as HR_sv and LR_mode1_noise0, respectively.