Dear Drew,

it is possible to extract thumbnail images from a Canon EOS 450D raw image file (CR2) using an old version 2.6.2 of metadata-extractor:

Metadata localMetadata = ImageMetadataReader.readMetadata(new File("<path to CR2 file>"));
ExifThumbnailDirectory myExifThumbnailDirectory;
myExifThumbnailDirectory = localMetadata.getDirectory(ExifThumbnailDirectory.class);
myExifThumbnailDirectory.hasThumbnailData(); // ---> returns true

Apparently, this does not work any more with version 2.8.1 of metadata-extractor.

Metadata localMetadata = ImageMetadataReader.readMetadata(new File("<path to CR2 file>"));
ExifThumbnailDirectory myExifThumbnailDirectory;
myExifThumbnailDirectory = localMetadata.getFirstDirectoryOfType(ExifThumbnailDirectory.class);
myExifThumbnailDirectory.hasThumbnailData(); // ---> returns false !!!

myExifThumbnailDirectory.getString(ExifThumbnailDirectory.TAG_THUMBNAIL_COMPRESSION));
does work on the same file (returns 6), for example.

Do I make any mistake?

I can provide an example image file if necessary.

Thank you.

Best wishes,
Guido