You want to preview a 15-page document in one glance — a single long image to drop in a Notion page, a Slack message, or a wiki. Fifteen separate JPGs is overkill.
The single-image use case
Common reasons: scroll-through previews on a website, sharing a deck in a chat tool that doesn't render PDFs inline, archival snapshots that capture the whole document at a glance, accessibility-friendly long images for screen readers (with proper alt text).
The result is a tall image — like a long screenshot of the whole document scrolled top to bottom.
How to make one
Two steps. First, convert the PDF to JPGs or PNGs. Second, stitch them together vertically. On macOS, Preview can do it: open all images, drag thumbnails into one canvas. On Windows or Linux, ImageMagick's `convert -append` does it in one command.
For a no-install option, use a free image-stitching site once you have the per-page JPGs.
Watch the image dimensions
A 15-page document at 300dpi gives you a single image roughly 1275×24,750 pixels tall. Most platforms accept tall images, but some have height limits — Instagram cuts at 4:5 ratio, Twitter limits long media. For social, drop to 150dpi and you halve the height.
For wiki and documentation use, the tall image is fine as-is.
Quick alternative
If you just need a preview, the PDF cover-to-image route gives you a single image of page 1 — usually enough to indicate the document's content without the full content.
FAQ
Can Flint output a single image directly?
Standard output is one image per page. Stitch into one externally — Preview, ImageMagick, or an online stitcher.
What about file size for a long image?
A 15-page document can be 5–15MB as a single tall JPG. Drop DPI to shrink.
Will it work for portrait + landscape mixed?
Yes, but the result has variable width. Decide whether to crop to common width or accept the mix.
What's the right format?
JPG for photos and most documents. PNG if sharp text matters and file size doesn't.
Long image, one glance. Start with PDF to JPG and stitch afterwards.