why are dng files produced bt denoise ai 6 times larger than the orignal

[williamv3826206]

After using lightroom denoise AI the size of the Denoise generated dng file is 6 times larger than my original 20 mg OM-Systems ORF file. Is that standard workflow? Topaz photo AI produces dng that is 5 times larger than my original ORF file. Can anyone tell me why these files are so much larger than the original ORF raw files?

[D Fosse]

They are demosaiced. One grayscale channel is encoded into three RGB channels.

It's also possible that the bit depth is higher (haven't checked that).

[Ian Lyons]

The Enhanced DNG file contains a demosaiced file, which is typically 3 times the original file size as it now contains RGB channels. Additionally, the Enhanced DNG file also contains a copy of the original mosaic data (i.e. a copy of the original raw file).

[Lightboxx]

i have just started to look at the AI denoiser.

i have some old DNG files that have lots of noise (small point and shoot camera).

how can i access the original raw data in the DNG if i need to?

if we have acess to that original data in the denoised DNG i could maybe delete the original DNG.

i mean i see no way to get back to the original data once i have denoised the file.

but that sure would be handy.

[D Fosse]

No, there's no way to get to the original mosaic raw data. So you can't delete the original file.

There is in fact a copy of the mosaic data embedded in the Denoise file - but it's only there for future improvements in the algorithm. You can't extract it. I don't know why they made this decision, but that's how it is.

[Lightboxx]

ok.. thanks for the answer.

[TheDigitalDog]

If you want to dive deeper into the two correct answers about the whys:

http://www.barrypearson.co.uk/articles/dng/linear.htm

The bit depth is still high bit.