If a graphics file cannot be opened in an image viewer, what should the next step be?

• A. Try a different viewer
• B. Examine the file's header data
• C. Check the file extension
• D. Reinstall the viewer

Answer: (B)

When a graphics file won’t open, the most informative next step is to inspect the file’s header data to confirm the true format. The header, or magic numbers, sits at the very start of the file and identifies what kind of data it actually contains, regardless of the file’s name or extension. This lets you distinguish between a file that is genuinely a particular image type and one that has been mislabeled or corrupted. For example, a JPEG typically starts with a specific byte sequence, while a PNG has a different signature; if the header doesn’t match the claimed format, the file may be misnamed or damaged. If the header confirms the expected image type and the file still won’t open, the issue is more likely corruption or truncation rather than a viewer problem. Checking the header gives you concrete information about the file's true format and integrity, guiding subsequent actions such as recovery, conversion, or discarding the file. Trying another viewer might help in some cases, but it won’t reveal the actual format or integrity, and reinstalling the viewer won’t fix a corrupted or mislabeled file. Extending from this, relying on the extension alone is unreliable since extensions can be wrong or misleading.