What the Extra Number in a Converted JPG Name Means

You convert two pictures called scan.png and scan.webp. The JPG results may be named scan.jpg and scan-2.jpg. The extra number tells you that two output names competed for the same place in the download. It doesn't describe the picture.

That small naming change can stop one successful result from replacing another in a ZIP. It can also confuse the person receiving the files if they assume the number refers to a page, a version, or the order in which the pictures were taken.

How two names end up the same

Different source extensions don't always produce different JPG names. Once both examples become JPG candidates, their extensions are the same. Names that differ only in letter case can also count as collisions. The allocator compares normalized names in lowercase and adds a suffix such as -2 or -3 when needed.

If scan-2.jpg is already taken, the allocator skips that name and looks for the next available suffix. A name with no collision is kept as it is. On a collision, the part before the extension keeps its spelling, and a suffix such as -2 is added with a lowercase .jpg extension. The lowercase comparison only decides whether names collide.

Other adjustments can happen before that comparison. Directory information and the original extension are removed from the result name, and some characters or reserved names are adjusted. A JPG name is a useful label for the downloaded result, but it is not a complete record of where the original came from.

Make your own mapping while the results are in view

Before you begin, make a simple list of the source files with a distinguishing detail for each. For example, record scan.png (front of package) and scan.webp (back of package). If repeated source names come from different folders, include the folder in your note.

When you convert pictures to JPG with LensUp, the free tier converts one source at a time, and Pro supports batches of up to 50 sources, subject to limits. After choosing the source images, check any selection messages. Use Convert to JPG, then read the result list and any failures.

Download and open the results. Add each output name to your note only after you have identified the picture. If a multipage TIFF is involved, record each expected page and its matching output, since one source can produce several JPGs. A suffix alone doesn't tell you which source or page a file represents.

If you need friendlier names, rename copies yourself with distinct, descriptive names, and update the note at the same time. Don't rename one file on top of another existing file. Keep the originals until the recipient has what they need.

Don't treat a suffix as an ID across runs

Names are allocated within each run. Converting a different selection, or retrying an item separately, can change which result gets a suffix. Your own note mapping sources to outputs gives context that the names alone can't.

Also check for exceptions. A batch can contain successful results alongside failed items. A progress warning can also mean the run stopped: the result for the source where it stopped was not kept, and later sources were not processed, so both need another run. With at least two successful JPGs, a ZIP is available; a single result is downloaded individually. Neither download choice proves the whole source list is complete.

Disclosure: This article was drafted with GPT-6.1 Terra for Yan Wang / LensUp; Yan Wang is affiliated with LensUp. The text was polished by an independent editorial AI and fact-checked by Codex. No human editor or owner reviewed or tested it. The evidence is source and public-page inspection and the retained synthetic Node checks, dated October 31, 2026. The Node checks covered synthetic JPG candidate names only. No real image conversion, TIFF decoding, ZIP creation, filesystem, or device test was performed.

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