The TNL file extension is associated with a thumbnail image file format. TNL files store picture thumbnails in a proprietary format. This format seems to be obsolete now without support.
TNL files are image miniatures that hold preview images. They are generated by image viewers and managers. TNL files can also be called image previews.
The TNL file format is not publicly documented. This makes it difficult to open and view TNL files in other programs. To open a TNL file, you can try a conversion tool like reaConverter.
TNL files fall under the Graphic Files category along with 523 other related file types. The TNL format was developed by an unknown creator. It was likely created with the XnView program originally.
To view the images inside a TNL file: Use a hex editor or text editor to remove the proprietary TNL header. Rename the file with a JPG extension. Open the renamed file as a normal JPG.
Programs cannot directly open TNL files now since the format is unsupported. To solve issues with TNL files: Determine the file format using the signature “magic bytes”. Then find a converter tool to open or fix the TNL file.
ThumbNailer