Can I use Vuescan raw DNG files from negatives in Lightroom?

Discussion in 'Digital Darkroom' started by davidlong, Sep 15, 2009.

  1. Since starting to use Lightroom recently, I decided that I liked its image manipulation controls much better than Vuescan's, and so for my color negatives I'd like to get a basic scan from Vuescan and then do the more extensive work in Lightroom.
    This is what I'm doing now:
    1. Lock the exposure and base color in Vuescan
    2. Scan my film. I use Vuescan's RGB histograms to set the black and white points for each image, and I tweak the overall white balance to get it in the ballpark. I leave the contrast low.
    3. Output full-size 48-bit TIFFs from Vuescan. Import those into Lightroom for further work.
    • I noticed that Vuescan also has a DNG raw output option. Thinking that might be better, I tried it, but when I import the DNGs into Lightroom, the image is still inverted. (And yes, I do have Vuescan set to color negative mode.)
      So my questions are:
      1. Is there any point in worrying about this, or are the 48-bit TIFFs just as good as what I'd get from the raw DNGs, assuming I could make them work. Would the DNGs save any disk space?
      2. Is there a way to invert the colors in Lightroom?
      3. If not, is there a way to get Vuescan to output a raw DNG but with the color inverted?
      • I currently have Vuescan's dust-and-scratch removal enabled and that is reflected in the TIFFs, but I'd be willing to give that up and do the spotting by hand in Lightroom if there was an advantage to using the DNGs.
    Read the chapter How Vuescan Works. Basically the DNG RAW file is raw, meaning no adjustments (inverting of colors) applied. It will give you all of the data that came out of the scanner. You'll have to invert and make any other corrections yourself. You can also take that DNG (or any other Vuescan generated file) and re-edit the file in Vuescan.
    How LR will work with all of that I don't know.
  3. Yes you can get Vuescan to save a properly inverted image. From the Vuescan users guide:
    Output | Raw save film

    (Professional Edition only)
    If this option is set, and if Output | Raw output with is set to "Save", then the film corrections are done before the raw file is written.
    Advanced Option: This option is displayed when Output | Raw file is set and when Output | Raw output with is set to "Save".
  4. Thanks Chris. "Raw output with: save" is the trick. I had it set to "scan". When you do that, another check box appears which says "Raw save film". That box makes Vuescan save the RAW output AFTER it has done the inversion (and dust removal too!)
  5. Question 1: 48 bit tiffs have the same raw information as the dng format does. For file format, it really comes down to what you are more comfortable with working in LR. Is DNG smaller? Well, yes it can be, but with a big caveat. The DNG files generated by Vuescan appear to not be compressed in any manner. However, our workflow is to import the DNGs into a LR "conversion" database that we use to enter the caption information into our files. The files are then exported as DNGs with the added metadata. These exported DNGs are significantly smaller (70-80 mb versus 121 mb for 4000 dpi 48 bit images). This import/exporting obviously adds an extra step to the workflow but saves on file size considerably. We advantageously use this step to enter the caption information so we are not bothered by the extra step involved with this workflow.
    Question 2: I read somewhere about inverting negatives in LR awhile back but didn't save the links. You can probably find them easily by doing a search. As you saw from Chris' answer, if you scan in negative mode and don't invert, dust removal won't be performed and you probably want that. I suppose you could scan in positive mode and apply dust removal, then invert in LR. I don't know if exposure behavior in Vuescan is different from negative to positive mode, having never tried test scans with those permutations.
  6. The data ViewScan provides is demosaiced so it doesn’t matter if you feed it DNG, what it calls (incorrectly), a Raw or a TIFF. Its not a Raw capture so LR and ACR are not using any demosaicing algorithms.

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