“Merge images into a PDF” sounds like a single, narrow task, and technically it is — but the situations that lead someone to actually need it are wildly different from each other. Here are six that come up constantly, including one that has nothing to do with paperwork at all.
1. Expense receipts, at the end of the month
You’ve been photographing receipts all month — coffee, taxi, the client dinner you’re pretty sure gets reimbursed. By the time the expense report is due, you’ve got thirty photos in a camera roll, in no particular order, at wildly different sizes because a thermal receipt and a hotel invoice are not the same shape.
This is where “fit to image” earns its keep: instead of forcing every receipt into an A4 mold with awkward white margins (or worse, cropping the bottom off a long one), each page becomes exactly the size of the photo behind it. Drop the images in, reorder them chronologically with drag and drop, pick a modest DPI and a higher compression level — receipts don’t need archival quality, they need to be legible — and you get one PDF that’s small enough to attach to an email without a “file too large” bounce.
2. A contract, signed on paper, photographed page by page
Someone sends you a contract to sign. You print it, sign it by hand, then photograph each page with your phone because that’s genuinely faster than finding a scanner. The pages usually come out slightly out of order — page 4 before page 3, because you photographed them off a stack instead of feeding them through a scanner.
Reordering the file list fixes the sequence in seconds. For this one, A4 portrait is the right call — it’s a formal document, and a fixed, consistent page size reads as one. Medium DPI (150–300) keeps the text legible without producing a file too heavy to send back. This is the single most mundane use of the tool, and also probably its most common.
3. Homework, whiteboards and last-minute submissions
A whiteboard photographed at the end of a lecture. A page of handwritten homework, photographed instead of scanned because it’s 11:52pm and the submission portal closes at midnight. The pages need to become one PDF, fast, because the portal accepts exactly one file per submission.
Speed matters more than settings here. Default resolution and compression are usually fine; the standard image pipeline (not the lossless flag) is the right choice too, since a whiteboard photo doesn’t need byte-for-byte preservation — it needs to be readable and under the upload limit.
4. Digitizing an old photo album or a box of family documents
This is the opposite situation: hundreds of images, and quality matters more than anything else, because these are the only copies of things that can’t be reshot. A childhood photo album, a folder of birth certificates and old letters someone finally scanned properly — the goal is one archival PDF that preserves exactly what was captured, no compression artifacts introduced along the way.
This is exactly what the “don’t modify images” flag exists for: JPEGs get embedded byte-for-byte identical to the source files, nothing re-encoded. The file will be larger than a compressed version — lossless doesn’t shrink photographic detail the way JPEG re-compression does — but that’s the point. And because large batches get built in chunks rather than held entirely in memory, merging 800 scanned pages doesn’t require a machine with an unreasonable amount of RAM to survive the process.
5. Property condition reports and inventories
Moving out of a rental, handing over a property to an insurer, documenting the state of equipment before a job. You walk through, photographing each room or item, and need one document that a landlord, agent or claims adjuster can actually open and page through — not a zip file of forty separate JPGs they’ll never all look at.
Fit to image again, since these photos need to stay at their real resolution and aspect ratio to actually show the detail that matters (a scuff on a wall, a scratch on equipment). A higher DPI setting here isn’t overkill — it’s the difference between a photo that proves something and one that’s too soft to be useful as evidence.
6. Converting a CBZ or CBR comic archive to PDF
This is the one that has nothing to do with paperwork, and it’s a genuinely common request.
CBZ and CBR aren’t special formats — a CBZ file is a ZIP archive of sequential page images (usually JPG or PNG, named so they sort in reading order), and a CBR is the same idea using a RAR archive instead. Comic and manga readers open them directly, but plenty of devices and situations don’t play along: an e-reader or tablet that only handles PDF, wanting to print a physical copy, or just wanting to send someone a single file they can open without installing a comic reader app first.
PDFImageMerger doesn’t open CBZ/CBR files directly — it’s honest about that, it works with images, not archives. But getting there takes one extra step:
- Extract the archive. A CBZ is already a ZIP under a different extension — most archive managers (7-Zip, or Windows’ built-in extractor once you rename the file to
.zip) will open it directly. A CBR is a RAR archive, so it needs 7-Zip or WinRAR instead. Either way, extract it to a folder — you’ll get the comic’s pages as individually numbered image files. - Drag that folder into PDFImageMerger. The page order is already baked into the filenames, and the reorderable list makes it trivial to fix anything that sorted wrong.
- Use “fit to image.” Comic pages have their own aspect ratio, and forcing them into A4 would mean either cropping panels or surrounding every page with white borders. Fit-to-image keeps each page exactly as it was drawn or scanned.
- Pick your trade-off. Archiving for the long term, or the source scans are already high quality? Use “don’t modify images” and keep everything byte-for-byte. Just want a reasonably sized file for a PDF-only e-reader? A mid-range DPI and compression level will shrink a hundred-page volume down to something that doesn’t eat your device’s storage.
Note
This same extract-then-merge approach works for any archive of sequential images, not just comics — a scanned book distributed as a ZIP of page photos, for instance. If the pages are images and they’re already named in order, PDFImageMerger doesn’t care what the container used to be.
The pattern underneath all six
An expense report, a signed contract, a family archive, a property inspection and a comic book have nothing in common — except that, at some point, someone had a stack of images and needed exactly one file out the other end, in order, at a quality and size they actually chose. That’s the entire job PDFImageMerger is built around.
Get PDFImageMerger on GitHub — free, open source, Linux and Windows.