Image to PDF

It tells you the resolution you are actually getting

Place a 600px photo across an A4 page and it is about 51 DPI. It looks fine on screen and prints like a fax.

Every other image-to-PDF tool will do that silently. This one reports the effective resolution per page, against the numbers print people use:

• 300 DPI and above — good. What a press expects.
• 150–300 — acceptable. Slightly soft up close.
• Below 150 — poor. Use a larger image or a smaller page.

Reducing the page size raises the DPI, because the same pixels are spread over less paper. An image too low-resolution for A4 is often fine on A5.

Page size is a real decision

Fit the page to the image makes each page exactly the image’s size. Right for scans and screenshots, where you want no margin and no scaling. Wrong for anything being printed, because a printer has to scale a non-standard page and will letterbox or crop it.

A4 or Letter gives a document that prints predictably. This is the default.

Placement decides what happens when the shapes disagree:

• Fit inside keeps the whole image and leaves margin. The safe choice.
• Fill the page crops the edges to leave no margin.
• Stretch distorts the image, and is named plainly so you do not choose it by accident.

Transparency is flattened onto white

Images are placed as JPEG, which has no alpha channel, so transparent areas become white. A transparent PNG logo will come out on a white rectangle rather than on the page background.

Flattening onto white rather than leaving it undefined is deliberate — the alternative in a PDF is usually black.

Order

Pages follow the order the files were selected in. Most file pickers sort alphabetically, so numbering your scans 01, 02, 03 rather than 1, 2, 3 is worth doing — otherwise page 10 lands between 1 and 2.

Nothing is uploaded

The PDF is built in this page. Scanned documents are frequently exactly the thing not to send to a converter.