How to convert a matrix containing a non-demosaiced image to a RAW image file, openable by Lightroom?

Question

I have a camera module, from which I am reading out "RAW", non-demosaiced image data (this camera module uses a Bayer BGGR filter). I am currently storing this in a MATLAB matrix. I am aware that MATLAB can demosaic this image for me, but I would like to use Adobe Lightroom's demosaicing algorithm and processing tools.Do any tools exist to convert this matrix (using MATLAB or otherwise) into a standard RAW file, such as Adobe's DNG format? I understand that DNG is very similar to TIFF, can this be leveraged?

Answer 1

Yes, but it is not as simple as saving the MATLAB matrix as a TIFF and changing the file extension to .DNG.

Lightroom needs a valid RAW/DNG file with the correct sensor metadata. Since your data is still non-demosaiced Bayer data, you would need to wrap that matrix into a proper DNG file and include the required tags: CFA pattern, bit depth, image width/height, black level, white level, color matrix, camera calibration data, and the correct orientation of the Bayer pattern.

The best path is to use Adobe’s DNG SDK or a DNG-writing library/tool that lets you create a real DNG container from raw CFA data. DNG is TIFF-based, but Lightroom expects much more than a normal TIFF structure. If the metadata is missing or wrong, Lightroom may open the file incorrectly, show strange colors, or reject it completely.

In practical terms, the workflow would be:

1. Keep the MATLAB matrix as the original Bayer data.
2. Confirm the exact Bayer layout, such as BGGR.
3. Save the data in the correct bit depth, usually 12-bit, 14-bit, or 16-bit.
4. Use the Adobe DNG SDK or another RAW/DNG tool to write a valid DNG file.
5. Add the correct DNG metadata so Lightroom knows how to demosaic and interpret the file.

So the answer is yes, it can be done, but you need to create a real DNG file, not just a TIFF. The hard part is not the pixel matrix; the hard part is the camera metadata that tells Lightroom how to interpret that matrix.