What is a TIFF file and why won't it open?

TIFF means Tagged Image File Format. The important word is tagged. A TIFF is a container that can hold many kinds of image data, plus notes about how to read them. That flexibility is why scanners, print shops, and some cameras like it, and why a phone or a browser often shrugs. There is no single “TIFF picture” the way there is a single JPEG.

If the file is a standard 8-bit TIFF, TIFF to JPG can decode it in the browser and save a JPG for every page. If it is 16-bit or an unusual variant, the page says so instead of crashing or inventing a picture.

Why it will not open

Web browsers never made TIFF a normal image format. A page can show a JPG, a PNG, a GIF, and in current browsers a WebP or an AVIF. Drop a .tif on a browser window and you often get a download or a blank view. Phones are similar. The Photos app on a computer may open a simple TIFF and still fail on the one a scanner just made.

The failure is usually one of three things. The file has more than one page, and the viewer only understands a single image. The pixels use 16 bits per channel, which is common in “archival” and raw-ish scans, and the viewer only implements 8-bit. Or the compression inside the TIFF is one the viewer never learned: old fax encodings, JPEG-inside-TIFF, or a tiled layout from a print workflow. The extension does not tell you which of those you have. The file has to be read to find out.

Multi-page TIFF is a document

Scanners love multi-page TIFF because one file can be a whole stack of paper. Fax software did the same. Opening it in a viewer that shows only page one makes the rest of the stack look missing. It is not missing. It is later in the file.

A useful conversion treats each page as its own JPG. A one-page TIFF downloads as one image. Several pages download as a ZIP, with the page number in the name. That is the same shape as exporting PDF pages. You can then look at page 4 without owning the program that made the scan.

16-bit and other odd TIFFs

Eight bits per channel is the ordinary photo: values from 0 to 255 for red, green, and blue, or a single 0 to 255 for gray. Sixteen bits can store a much finer ramp, which matters while you are editing a scan and matters less once you are emailing a picture. Many simple decoders either refuse 16-bit data or misread it and emit a black or noisy image. A black image that looks “successful” is worse than an error.

This converter checks the sample size. If a page uses more than 8 bits, you get a clear message that names the bit depth and tells you to export an 8-bit TIFF or a JPG from the program that created the file. BigTIFF, which is a later variant for very large files, is refused the same way. So is a file that is not a TIFF at all, and a TIFF whose page list is truncated or loops. Floating-point samples and color modes the decoder does not know are reported rather than drawn as garbage.

Some 8-bit files still will not decode, because the compression is unusual. Those get an error on that page too. The rest of a batch continues. The file is not uploaded to another server to retry.

What a JPG of a TIFF is, and is not

The JPG is a new picture made from the decoded pixels, flattened onto white where the TIFF had transparency. You choose a quality. 92 is a strong default for a scan you still want to read. Lower it when the TIFF is a huge photograph. JPEG cannot hold 16-bit precision or the extra TIFF tags, so scanner notes stay behind. That is fine when the goal is a file that opens, and the wrong goal when you are archiving a master.

Keep the TIFF if it is the master. Make the JPG as the copy you send. GPS and camera tags are not copied into the new JPG, which is what you want before you attach a scan to an email, and it is another reason not to throw away the original if those tags mattered.

A sensible way through a file that will not open

The decoder loads only on the TIFF page, and only when a conversion starts. Open TIFF to JPG with the file still on your machine. A success gives you pages that open anywhere. An error names the next step instead of freezing the tab.

• Confirm the name ends in .tif or .tiff. A download is sometimes a PDF or a ZIP that was mislabeled.
• Try TIFF to JPG. A normal 8-bit scan, including multi-page, should come back as JPGs in a ZIP.
• If the message says 16-bit, BigTIFF, or an unsupported page, open the file in the scanner software, Photoshop, or Preview and export an 8-bit TIFF or a JPG. Then you can shrink that JPG here if you need to.
• If you needed a PDF rather than pictures, convert to JPG first and then use JPG to PDF, one image per page, in the same order.