Decoding Light L16 .lri raw files

I am interested in reverse engineering the file format of the Light L16 camera.

The Light L16 is a discontinued camera with 16 lenses and produces .lri files that are accessible only through their proprietary Lumen software.

So far I have extracted some Protobuf .proto schemas from the lricompression.dll using pbtk, and have created a project at GitHub - dllu/lri-rs: Rust code to deal with .lri files from Light L16 camera with the said proto files. However I have had no luck actually decoding the .lri file.

Interesting facts:

  • The lri files seem to be of identical size even for different shots, suggesting that they are not compressed.
  • Running diff on hexdumps of lri files reveals that some parts are the same, including a long segment near the end.

However I am not experienced with reverse engineering file formats and have gotten pretty stuck. Does anyone have any ideas how I can proceed?

Original JPG preview from the L16 camera:

Corresponding .lri file (170 MB): https://i.dllu.net/L16_00078.lri (I also uploaded this to raw.pixls.us but I don’t know if it will be accepted).

Relevant old threads:

p.s. Yes I know that the image quality produced by the L16 is terrible. But it is still fun to figure out how to decode its files.

Perhaps @LebedevRI or @heckflosse can help?

Can you dump any of the metadata using exiv2/exiftool?

exiv2 was unable to read the .lri file.

However I have the metadata from the JPEG preview:

File name       : L16_00078_1.jpg
File size       : 4942810 Bytes
MIME type       : image/jpeg
Image size      : 4160 x 3120
Camera make     : Light
Camera model    : L16
Image timestamp : 2017:09:27 23:24:21
Image number    :
Exposure time   : 1/625 s
Aperture        :
Exposure bias   : 0 EV
Flash           : No flash
Flash bias      :
Focal length    : 28.0 mm (35 mm equivalent: 28.0 mm)
Subject distance:
ISO speed       : 100
Exposure mode   :
Metering mode   :
Macro mode      :
Image quality   :
Exif Resolution : 4160 x 3120
White balance   :
Thumbnail       : None
Copyright       :
Exif comment    :