Scanned images become unreadable primarily due to file compatibility issues or file corruption. A scanned image is a digital picture of a document or object, saved as a specific file type (like TIFF, JPEG, or PDF). You can't open it if your software lacks the necessary support for that specific format. Alternatively, errors during the scanning process, saving, transferring, or storing the file (corruption) can damage its internal structure, making software unable to interpret it correctly. This differs from simply viewing a photo taken with a camera, which often uses common formats readily supported by many applications.

For example, specialized scanners in healthcare often output images in the DICOM format, requiring specific medical imaging software for viewing. Similarly, a TIFF file scanned on a multifunction printer might open in Adobe Photoshop but fail in a basic image viewer that only handles formats like PNG or JPEG. Industries relying heavily on scanning, like archiving or engineering, frequently encounter proprietary formats tied to specific scanner brands or specialized document management systems.

The main limitation is the dependency on compatible software for the specific scanned format, impacting accessibility and requiring users or organizations to invest in suitable viewers. File corruption, from factors like damaged storage media or interrupted transfers, is a significant risk causing permanent data loss. This emphasizes the critical need for choosing widely supported formats when possible and implementing robust backup practices to preserve valuable scanned documents and images effectively.