ISIC Datasets Duplicate Removal Strategy

Instructions for the removal of duplicate image files from within individual ISIC datasets and across all ISIC datasets.

If you use any part of the duplicate removal strategy in a research project, please consider citing our paper:

@article{cassidy2021isic,
 title   = {Analysis of the ISIC Image Datasets: Usage, Benchmarks and Recommendations},
 author  = {Bill Cassidy and Connah Kendrick and Andrzej Brodzicki and Joanna Jaworek-Korjakowska and Moi Hoon Yap},
 journal = {Medical Image Analysis},
 year    = {2021},
 issn    = {1361-8415},
 doi     = {https://doi.org/10.1016/j.media.2021.102305},
 url     = {https://www.sciencedirect.com/science/article/pii/S1361841521003509}
} 

Please read the DISCLAIMER before using any of the methods or code from this repository.

1. Prerequisites

Download FSlint from here: http://www.pixelbeat.org/fslint/

Note that when using the Save function within FSlint to save file lists, it will save the files you have highlighted.

The following steps assume that you have downloaded and organised your ISIC datasets into the following directory structure:

ISIC
├─ 2016
|   └─ test
|   └─ train
├─ 2017
|   └─ test
|   └─ train
├─ 2018
|   └─ test
|   └─ train
├─ 2019
|   └─ test
|   └─ train
└─ 2020
    └─ test
    └─ train

2. Duplicate Removal Process

1. Make a copy of your ISIC dir (e.g. ISIC (Master)) and rename the copy to ISIC (A). If you make any mistakes, you can easily go back to your original Master dir to start again.

2. In 2019/train, find all 2,074 files containing the _downsampled suffix and move them into a new folder called downsampled in the ISIC (A) dir.

3. Run the remove_downsampled_suffix.py script from within the ISIC (A)/downsampled dir. This removes the _downsampled suffix from the downsampled files so that they can be compared by name to files in all the other ISIC train/test sets.

4. Run command fslint-gui in a Terminal to open FSlint.

5. Once FSlint has loaded, click on the Search path tab and remove any default dirs listed using the Remove button.

6. In FSlint, click the Add button and add the ISIC (A)/downsampled dir.

2.1 Delete Downsampled Duplicates

7. In FSlint, select the Name clashes option (left panel) and ensure that the $PATH checkbox is unticked. Select Same name (ignore case) in the dropdown. Click the Add button and add the ISIC (A)/2016/test dir to the Search path. You should now have two paths in the Search path window: ISIC (A)/downsampled and ISIC (A)/2016/test. Click the Find button. When the results are returned, click Select > within groups > Select all but first to select only the downsampled files in the duplicate results. When all the files you want to delete are highlighted, click the Delete button. Note that no test image files should be selected in the search results. If any test image files are selected, unselect them individually by holding CTRL and click left mouse button on the image files you want to unselect. Repeat this step for each of the remaining individual ISIC test dirs: 2017 - 2020. Ensure that you highlight the current year dir in the Search path window and click the Remove button before moving on to the next year dir.

8. In FSlint, highlight all paths shown in the Search path window and click the Remove button.

9. In FSlint, select the 'Duplicates' option (left panel). Add the following dirs to the Search path: ISIC (A)/downsampled and ISIC (A)/2016/test. Click the Find button. When the results are returned, click Select > within groups > Select all but first to select only the downsampled files in the duplicate results. When all the files you want to delete are highlighted, click the Delete button. Repeat this step for each of the remaining individual ISIC test dirs: 2017 - 2020. Ensure that you highlight the current year dir in the Search path window and click the Remove button before moving on to the next year dir. Note that at this stage, binary duplicates may exist within each test set. Ensure that only downsampled image files are selected when deleting image files. If any test image files are selected, hold Ctrl and click left mouse button to unselect individual image files.

10. In FSlint, highlight all paths shown in the Search path window and click the Remove button.

11. In FSlint, select the Name clashes option (left panel) and ensure that the $PATH checkbox is unticked. Select Same name (ignore case) in the dropdown. Click the Add button and add the ISIC (A)/2016/train dir to the Search path. You should now have two paths in the Search path window: ISIC (A)/downsampled and ISIC (A)/2016/train. Click the Find button. When the results are returned, click Select > within groups > Select all but first to select only the downsampled files in the duplicate results. When all the files you want to delete are highlighted, click the Delete button. Note that no train image files should be selected in the search results. If any train image files are selected, unselect them individually by holding CTRL and click left mouse button on the image files you want to unselect. Repeat this step for each of the remaining individual ISIC train dirs: 2017 - 2020. Ensure that you highlight the current year dir in the Search path window and click the Remove button before moving on to the next year dir.

12. In FSlint, highlight all paths shown in the Search path window and click the Remove button.

13. In FSlint, select the 'Duplicates' option (left panel). Add the following dirs to the Search path: ISIC (A)/downsampled and ISIC (A)/2016/train. Click the Find button. When the results are returned, click Select > within groups > Select all but first to select only the downsampled files in the duplicate results. When all the files you want to delete are highlighted, click the Delete button. Repeat this step for each of the remaining individual ISIC train dirs: 2017 - 2020. Ensure that you highlight the current year dir in the Search path window and click the Remove button before moving on to the next year dir. Note that at this stage, binary duplicates may exist within each train set. Ensure that only downsampled image files are selected when deleting image files. If any train image files are selected, hold Ctrl and click left mouse button to unselect individual image files.

14. In FSlint, highlight all paths shown in the Search path window and click the Remove button.

15. Run the 'add_downsampled_suffix.py' script from within the ISIC (A) dir. This adds the _downsampled suffix back to the remaining downsampled filenames.

16. Move all remaining downsampled files in the ISIC (A)/downsampled dir back into the ISIC (A)/2019/train dir.

2.2 Delete Binary Identical 'Within-Train-Sets' and 'Across-Train-Sets' Training Images

17. In FSlint, ensure that the 'Duplicates' option (left panel) is selected. Highlight all paths shown in the Search path window and click the Remove button. Add the following dirs to the Search path: ISIC (A)/2016/train, ISIC (A)/2017/train, ISIC (A)/2018/train, ISIC (A)/2019/train, and ISIC (A)/2020/train. Click the Find button. When results are returned, if you want to delete the oldest duplicate image files, click Select > within groups > select all but newest. If you want to delete the newest duplicate image files, click Select > within groups > select all but oldest. Click the Delete button to delete the selected image files.

18. In FSlint, highlight all paths shown in the Search path window and click the Remove button.

2.3 Delete Binary Identical Training Images That Exist 'Across-Train-and-Test-Sets'

19. In FSlint, ensure that the 'Duplicates' option (left panel) is selected. Add the ISIC (A)/2016/train dir and the ISIC (A)/2016/test dir to the Search path. Click the Find button. When results are returned, if you want to delete the oldest duplicate image files, click Select > within groups > select all but newest. If you want to delete the newest duplicate image files, click Select > within groups > select all but oldest. Click the Delete button to delete the selected image files. Ensure that you only have train image files selected in the search results. To unselect individual test images, hold Ctrl and click left mouse button on the image file(s) in the results window you want to exclude from deletion.

20. In FSlint, highlight all paths shown in the Search path window and click the Remove button.

21. Repeat steps 19 to 20 for each of the remaining year dirs (2017 - 2020).

2.4 Delete Binary Identical 'Within-Test-Sets' Test Images

22. In FSlint, ensure that the 'Duplicates' option (left panel) is selected. Highlight all paths shown in the Search path window and click the Remove button. Add the following dirs to the Search path: ISIC (A)/2016/test, ISIC (A)/2017/test, ISIC (A)/2018/test, ISIC (A)/2019/test, and ISIC (A)/2020/test. Click the Find button. When results are returned, if you want to delete the oldest duplicate image files, click Select > within groups > select all but newest. If you want to delete the newest duplicate image files, click Select > within groups > select all but oldest. Click the Delete button to delete the selected image files.

3. Image File Deletion Logs

The table below shows a summary of all the file lists you can download from this repository (file_lists dir) containing image file names of the images that were deleted using the above duplicate removal strategy. Note that for items 6 to 11 (Order column) the Select > within groups > Select all but newest option was used in FSlint to mark files for deletion.

Order	Filename	Delete Count
1	downsampled_vs_2016_test_duplicate_filename_deleted.txt	95
2	downsampled_vs_2017_test_duplicate_filename_deleted.txt	594
3	downsampled_vs_2016_test_binary_duplicate_deleted.txt	1
4	downsampled_vs_2016_train_duplicate_filename_deleted.txt	291
5	downsampled_vs_2017_train_duplicate_filename_deleted.txt	946
6	all_train_duplicates_deleted_(all but newest).txt	12,038
7	2016_train_vs_2016_test_duplicates_deleted.txt	2
8	2017_train_vs_2016_test_duplicates_deleted.txt	82
9	2017_train_vs_2017_test_duplicates_deleted.txt	2
10	2019_train_vs_2016_test_duplicates_deleted.txt	258
11	2019_train_vs_2017_test_duplicates_deleted.txt	1
12	all_test_duplicates_deleted_(all but newest).txt	1,592