A file extension is just a label, and labels can be wrong. A file named photo.jpg might actually be a PNG, or even something that will not open as expected. Detecting the real format reads the file itself rather than trusting the name.
Why the extension can lie
Renaming a file does not change its contents. People rename images to dodge upload filters, and some apps export with a misleading extension. When an image refuses to open or upload, a mismatched format is often the cause.
How to detect an image's format
- Open the Image Format Detector.
- Add the file.
- Read the detected true format.
The file is inspected in your browser, so nothing is uploaded.
What to do with the answer
- If the real format is not what you need, convert it with the Universal Image Converter.
- If an upload keeps failing, check that the extension matches the actual format.
- Use detection to confirm a file is a real image before opening it.
Reading deeper
To see the full set of hidden details inside an image, use View Image Metadata.
Frequently asked questions
Why does my image have the wrong extension?
Files can be renamed without changing their contents, and some apps export with a mismatched extension. Detecting the real format clears up the confusion.
How do I find an image's true format?
Open the Image Format Detector and add the file. It reads the file's actual data rather than trusting the name.
Is the file uploaded to detect its format?
No. Detection runs in your browser, so the file stays private.