File Type Detection - drewnoakes/metadata-extractor GitHub Wiki

ImageMetadataExtractor determines the file's type automatically from the first bytes of the file. It uses the FileTypeDetector class for this purpose, and you can also use it in your code if needed.

For example:

FileType fileType = FileTypeDetector.detectFileType(myStream);

if (fileType == FileType.Jpeg) {
    // ...
} else if (fileType == FileType.Png) {
    // ...

The detector will return FileType.Unknown if it cannot determine the file type.

Note that detection is based on only the first few bytes of the file and does not guarantee that the image and/or metadata can be successfully decoded.