How to turn photos of documents into a single PDF

Lay each page flat on a dark, plain surface, in good daylight and without flash glare. Hold the phone upright, shoot from straight above so the page comes out as a rectangle, fill the frame with the page, and check every photo is sharp before moving on to the next.

We converted five 12-megapixel photos, 7.4 MB together, with JPG to PDF and merged them. Each page came out almost exactly the size of its photo, so the merged PDF was 7.4 MB too: too big for many upload forms. Compress PDF then shrank it by 73 to 96%, depending on the level, by storing each photo at a smaller size.

On a full A4 page, Balanced keeps about 140 pixels per inch, which is plenty for normal-size text, and our five pages came to 690 KB: small enough for email and most upload forms. Strong keeps about 95 pixels per inch; it reached 310 KB, but small print can start to blur, so zoom in on the result before you send it. Light is for documents that may be printed: the pages stay sharp and the file is still much smaller than the original.

Each photo is scaled to fit an A4 page in portrait orientation. A page photographed with the phone held upright fills almost the whole page. A photo taken sideways fills the width of the page and leaves the rest blank, so for documents, shoot in portrait or rotate the photos before converting.

HEIC photos from an iPhone go through HEIC to PDF the same way. Each page is stored as a high-quality JPEG inside the PDF, so a 12-megapixel HEIC photo makes a page of about 2 MB, the same as from a JPG, and Compress PDF shrinks it just as well.

The pages stay images: the text in them is not searchable or selectable unless you use OCR software. Keep the original photos until the PDF has been accepted, in case a page needs to be taken again. If you only need to send some of the pages, Split PDF can extract them from the merged file.

The five photos are Unsplash photographs that ship with Edubuntu, scaled to about 12 megapixels and saved as JPG at quality 92, about the size of the photos a phone takes. We converted, merged and compressed them with this site's tools, which run the same code as our servers, and measured each result. Photos of plain paper with text usually compress even better than these pictures.