URL Deduplication in the Image Scraper

The same image, three times over

Scrape a gallery and you often end up with the same picture more than once — a thumbnail and a full-resolution copy, or the identical file linked from several places. Left alone, those repeats eat slots in your download queue and clutter your results. The Deduplication tab in Bulk Image Downloader From URL List finds those repeated URLs and helps you clear them out before anything moves downstream.

One important boundary: this is URL-level deduplication. It works on the image addresses in the scraper, not on what the images look like. Catching near-identical images by visual similarity is a separate job on the options page. Here, the focus is duplicate links.

Pick a removal strategy

Before detecting, choose how duplicates should be resolved. There are three strategies, and the right one depends on what you value in a group of repeats:

Keep first occurrence — the first URL in a group wins and the rest are removed. Simple and predictable when order is all that matters.
Keep largest — when a group has a thumbnail and a full-resolution version, this keeps the big one every time. This is usually what you want for quality.
Manual selection — the extension groups the suspected duplicates and you pick the keeper in each group yourself. The most control, for when you want eyes on every decision.

Detect and review

Once you have a strategy, hit Detect Duplicates. The extension produces a deduplication report showing how many duplicates were found, how many images would be removed, and how many would be kept. You are not flying blind — you see the impact before committing.

You can expand any group in the report to see every URL in it side by side. That is the moment to confirm the strategy is doing what you expect, especially with Keep largest, where the report shows the size comparison driving the choice.

Confirming the removal

Pick your strategy: keep first, keep largest, or manual.
Click Detect Duplicates and read the report.
In manual mode, check what should go in each group, then Remove Selected — or Cancel if you change your mind.
For the automatic strategies, confirm with the quick Yes, Remove prompt and it is done.

If you change your mind

Mistakes happen, and dedup is the kind of operation where a wrong call can be costly. Undo Last Removal brings the removed images back, so an aggressive pass is recoverable. That safety net makes it reasonable to try Keep largest, check the result, and undo if it was not what you wanted.

Where dedup fits in the workflow

Run deduplication after filtering and before downloading. Filters cut the obvious junk — wrong sizes, unwanted formats, third-party domains — and then dedup removes the repeats from what is left. The result is a lean list where each image appears once at the size you want. Clean list in, clean download out: that is the standard worth holding to, and the report plus undo make it safe to get there. When you are satisfied, send the deduplicated set to a download task.