Vuescan DNG - raw or tiff output

[fotopan]

Hello,
I’d like to ask: what is exactly "Update Vuescan/Silverfast DNGs” function doing and does it matter if I output files for NLP as DNG raw or DNG tiff from VueScan?

I saved a scan from VueScan as both DNG tiff and DNG raw and imported the files to Lightroom. Right after the import they looked visibly different but only until I ran the "Update Vuescan/Silverfast DNGs” on them - they started to look identical to my eye then. After conversion there are differences between both DNGs albeit very minor ones.

Does it mean I can output files for NLP as DNG tiff from VueScan?

[PhilBurton]

@fotopan

I saved a scan from VueScan as both DNG tiff and DNG raw

Did you process these files in NLP?

and imported the files to Lightroom. Right after the import they looked visibly different but only until I ran the "Update Vuescan/Silverfast DNGs” on them - they started to look identical to my eye then. After conversion there are differences between both DNGs albeit very minor ones.

Conversion = ??

[nate]

@fotopan

I’d like to ask: what is exactly "Update Vuescan/Silverfast DNGs” function doing and does

It updates some of the metadata on the image so that Lightroom can recognize what raw camera profile to use.

If you are using Vuescan and common scanner, it probably won’t be necessary. But it is usually necessary with Silverfast (which is really bad at providing consistent metadata).

@fotopan

does it matter if I output files for NLP as DNG raw or DNG tiff from VueScan?

It should be DNG RAW and the output should be set to 48bit RBG (it will not work if you select “auto” or "64bit RGBi on the output tab)

@fotopan

Right after the import they looked visibly different but only until I ran the "Update Vuescan/Silverfast DNGs” on them - they started to look identical to my eye then. After conversion there are differences between both DNGs albeit very minor ones.

In some cases, they may look similar. But DNG has a couple of advantages in terms of consistency and control, so that would be my recommendation.

-Nate

[fotopan]

I always feed DNG files to Lightroom/NLP, I was curious however if I should always output DNG with VueScan Output\Raw file (Raw DNG format set to ON), or if I can output the DNG with VueScan Output\TIFF file (with TIFF DNG format set to ON).

If I understand correctly, the TIFF file output from VueScan has gamma and Color tab corrections applied while Raw file is outputted without these corrections. I compared “raw” DNG file with “TIFF” DNG file in Lightroom and as I wrote right after the import they looked visibly different but only until I ran the "Update Vuescan/Silverfast DNGs” on them - both DNG files started to look identical to my eye then hence my thought that maybe the "Update Vuescan/Silverfast DNGs” equalizes gamma somehow between files?

I ask because I have thousands of frames scanned with VueScan as Color Negative only to find now that NLP conversions from DNGs scanned as “Image” (without orange masks partially removed by VueScan) are much better.

I found that if I output DNGs from VueScan with TIFF file option (with orange mask added using VueScan Color tab) I can revert the “Color Negative” orange mask removal and get better conversions than without the mask, I’d like however to better understand the difference between “raw” DNG and “TIFF” DNG before deciding on the workflow.