9x Finder: duplicate images, actually found
A desktop application that compares what is inside the images, not the file name, and finds both exact duplicates and lookalikes.
In brief
- 9x Finder looks for duplicate or similar images inside the folders the user selects.
- The search is split across several threads, so the scan uses every available core instead of working through one file at a time.
- It has two modes: finding images that are similar to each other, and looking for one image inside another.
- The similarity threshold is adjustable, so you decide how alike two images have to be to count as the same one.
What the problem was
Image folders grow by accumulation: the same photo saved twice under different names, the cropped version next to the original, the same export repeated at a different resolution.
Looking for duplicates by file name is useless, because the name is precisely the thing that changes. What is needed is comparing images by what they show. And doing that across thousands of files takes time, unless the work gets distributed.
How it works
You point it at the folders to analyse and choose the mode. The first looks for images similar to each other within the set; the second looks for a given image contained inside another, which is the case with a crop or a detail taken from a larger shot.
The accuracy threshold decides how strict the comparison has to be: raise it and you only get practically identical duplicates, lower it and the variants come out too. A path filter lets you narrow the analysis to part of the folder tree, and it can be switched on and off without redoing the selection.
Why the search is split across threads
The scan is divided into parallel threads, which is the difference between an acceptable wait and a scan you leave running overnight.
Results are browsed in a list alongside a preview of the selected image, with a counter showing how far the scan has got. The list updates while the work goes on, and the stored data can be cleared to start again clean.
What was delivered
- Complete source code
- Detailed comments in the code
- Visual customisation of the interface
- Responsive layout
Technical details
- Platform: Windows, desktop application
- Year: 2023
- Status: Delivered
- Technologies: Python, Windows Desktop, Multithreading
Do you need software like this?
If you have a process you handle by hand today and would like to automate, tell me about it: we work out together whether it makes sense to build a tool on top of it.
Need something similar? This project is an example of desktop app development. The first meeting and the quote are free: write to me and we will talk it through.

