Why TIFF scans are converted to PDF
Office scanners, fax machines and archive systems often save scans as TIFF. TIFF files are large and many phones, browsers and websites cannot open them. PDF is the format people expect for documents, and it opens almost everywhere.
What happens when you convert
The TIFF is decoded in your browser — uncompressed, LZW, Deflate and PackBits TIFFs with 8-bit greyscale or colour are supported — and placed on a PDF page. Choose “Combine into one PDF” to join several scans in order, and choose “Fit to image”, A4 or US Letter page sizes.
Important limitation
Only the first page of a multi-page TIFF is read. If your scanner saved a whole document as one multi-page TIFF, you will get only the first page — split the TIFF into single pages with your scanner software or a desktop image program first. Fax-style 1-bit black-and-white TIFFs with CCITT compression are also not supported.
Common problems and how to fix them
“Could not be read”: the TIFF uses an unsupported compression; open it in a desktop viewer and save it as PNG or JPG, then use Image to PDF. The PDF is very large: compress it with Compress PDF. Scans are crooked: straighten the PDF with Deskew Scanned PDF.
Good habits
Scan at 200–300 DPI for documents, keep the original TIFF files in your archive, and run OCR PDF on the result to make it searchable.