Why are my RAW files created by Vuescan so dark in Aperture?

LV.bob wrote:

...I know I can automate the adjustments at import which might make this less of an issue but I wonder if saving in TIFF is nearly as good. Some of the pictures have a wide dynamic range with lots of shadow detail.

My feeling is that you should do as much adjusting as possible during the scan; take the time to do a preview or two and adjust before the final scan. In my experience (Nikon 8000ED) it takes time to get scanning done properly. Note that scanning will cut off the dynamic range of original film; how much depends on the scanner and the skill of the operator.

And IMO saving in TIFF probably is less good - - unless of course you get a perfectly balanced scan to start with.

HTH

-Allen

Sounds like your skill level is well above mine. Hopefully I will never do another scan 😕 but I do look forward to hearing what workflow you find gives best results.

-Allen

What is the RAW format Vuescan uses? Is it a TIFF? Is it a RAW format that Aperture understands?

If it is a TIFF, and the gamma is 1 then it is normal that you images are dark. Vuescan probably adjust the gamma on the fly to 2.2, but when it saves it writes a gamma of 1.

That said, I don't feel there is a good reason to save a scan as RAW. It will be basically the same as a 16-bit TIFF, except that the TIFF has the demosiacing and gamma applied. These operations will not make you loose any latitude. Also, note that a TIFF file will have a colorprofile applied to the image and a RAW file does not. So what use is your IT8 target on a RAW file?

If you still fell like scanning RAW is the way to go, make yourself a adjustment preset in Aperture. Just create a curve that resembles a gamma 2.2 curve and save that as an adjustment preset. But can you appreciate that this is similar to creating a TIFF file: you let Aperture apply a color profile and do the demosiacing, then you apply a gamma correction with the curve preset.

Note: I've never used Vuescan, only Silverfast. Silverfast doesn't create RAW files. So the above information is based on the difference between a camera RAW file and a TIFF.

Aperture does support Adobe's DNG format. I don't know what is different about what Vuescan is outputting.

Note that DNG is just an Adobe attempt to standardize the digital images capture world to Adobe's protocol that the main players like Nikon and Canon do not subscribe to.

-Allen

My frustration has been that I am doing the processing twice which is pointless. I need to choose a workflow. Mind you that if Apple supported the full DNG specification, it would be able to deal automatically with these RAW scanned DNG files (I believe they are linear DNGs) and automatically compensate during import just as Lightroom does. I am using the trial version of Aperture - which I feel really comfortable using - but I think I may take Lightroom for a spin prior to making a final choice of software.

As I tried to clarify, there is no benefit in saving as RAW from a scanner. Just save as a normal 16-bit TIFF and you'll and up with a simplified workflow and no loss of data nor detail. Actually, a DNG is internally just a TIFF.

Mind you that if Apple supported the full DNG specification, it would be able to deal automatically with these RAW scanned DNG files (I believe they are linear DNGs) and automatically compensate during import just as Lightroom does. I am using the trial version of Aperture - which I feel really comfortable using - but I think I may take Lightroom for a spin prior to making a final choice of software.

[...]

If Apple fully-supported the DNG specification, then the RAW Fine Tuning adjustment would be available with its auto-exposure button to get a good starting point for tweaking the images.

You could provide Apple with feedback via, Aperture>Provide Aperture Feedback.

If I continue with Aperture, I am thinking that I will save these files as RAW TIFFs and do the gamma adjustment at import. This should streamline the workflow by making it possible to scan two 4x5s at one without the need to tweak each one in the scan and then do all my processing in Aperture (or Lightroom). I will just trust the scanner.

You shouldn't trust your scanner, just as you shouldn't always trust matrix metering or 'I'll fix that in post". Aiming for the best starting material is aiming for the best results. So instead, carefully examine each scan, which will not take you that long BTW.

I will still create the scanner profile of the IT8 target which I should then be able to use as a proofing profile to compensate for any color bias in the Fuji Provia film used. Perhaps I am wrong about this.

Actually, you're wrong on this. The IT8 provides an input profile, and not an output profile or working space. Imagine scanning a slide and printing it. Softproofing for IT8, then you can't softproof for your printer and vice versa.

Your post has allowed me to really think through my workflow and I really appreciate the input I've received in this thread. Now, I just wish I could get Apple to add support for Linear DNG (or whatever format Vuescan RAW DNG is which I know contains three colors per pixel rather then one as in Camera Raw) which would provide the additional tools to deal with these DNGs at import.

Although linear DNG support would indeed be nice for unsupported camera's, it is not necessary here. If Vuescan DNG has three channels, than it is a TIFF. (since demosiacing MUST have been applied, there are no scanners with a Foveon sensor as of yet)

Well to cut a very long story short just use TIFF for scans. It's a necessity for proper colormanagement and will simplify your workflow.

Allen, Aperture does NOT support linear DNG, which is what Vuescan apparently uses as output.

Non-linear DNG is the same as a manufacturer RAW i.e. No demosiacing, gamma-correction or colorprofile applied.

Linear DNG is a RAW file to which the demosiacing has been applied (the sensor-manufacturers secret part), but not yet gamma correction, nor a colorprofile.

Ir. Bob wrote:

Allen, Aperture does NOT support linear DNG, which is what Vuescan apparently uses as output.

Non-linear DNG is the same as a manufacturer RAW i.e. No demosiacing, gamma-correction or colorprofile applied.

Linear DNG is a RAW file to which the demosiacing has been applied (the sensor-manufacturers secret part), but not yet gamma correction, nor a colorprofile.

So much for DNG as a "standard." I need to say Apple supports most DNG file types, like it supports most cameras' RAW files.

If VueScan is outputting Gamma 1… is there any way to simply change the Gamma to 2.2 when you bring it into Aperture? Can you do this on an individual photo basis?

Also, I'm not an expert by any means… but I can see the benefit of shooting RAW with a camera, b/c of the xtended range you get (exposure, recovery, etc). But wouldn't you assume that this same kind of thing is happening in the scanner? That VueScan is gathering a wider range of information? Or is that wishful thinking?

I have used Vuescan for years. As I understand it, the last time I looked, Vuescan only outputs Linear DNG and Aperture does not read this format.

I use TIFF and while the files are massive, the results are excellent. Have done several thousand slides.

--

DiploStrat 😉

Please take a look at this website to see the difference between RAW and TIFF.

As you can see, RAW and TIFF are nearly the same. They only differ in demosaicing and gamma correction and color profile embedding. Scan as a 16-bit TIFF and in ProPhotoRGB and you basically have a RAW file in terms of "xtended range".

What is the added benefit of applying a different color profile or gamma curve later in your workflow when scanning photo's? I don't think there is any, so I think scanning in RAW is pointless. It's not like you only have one shot or limited time to create a good 'negative' as is the case in non-studio photography, you already have a good negative, your just creating a faithful reproduction of it on a different (digital) medium.

From a different forum:

I have been using Vuescan since last century (!) and I like to clear up some confusion on the different file formats discussed.

Scanning with Vuescan in Raw means that you capture all what the scanner can deliver (max 3 x 16 bit plus an infrared channel 16 bits, if available in the scanner) this format captures everything and adjusts nothing.

Next stage in Vuescan is to adjust the raw data with respect to the scanner profile and the working space you desire (typically Adobe RGB). Both those steps is what you do when you press SCAN. When the scan is finished the above adjustments have been accomplished and you can see the picture (the raw file in itself is very, very dark as it is in another colour space). As you probably noticed, the scan took a while, so you don't want to do that again - therefore save the RAW file as your original, particularly if you also where able to capture the infrared channel.

Next step is to adjust the picture to your liking - brightness, contrast, etc.. Film transparency is different for infrared, which is why the IR channel can be used to minimize effects on dust and scratches. The routine included in Vuescan for doing just that is very good (and probably one of the few, if not the only one, also working with Kodachrome).

Having done all that - picture to your liking, dust and scratches removed - it is time to save the picture. Now you can do that in TIFF (except the IR channel, which makes no sense outside Vuescan). The TIFF file saves everything of the picture you have adjusted as above - 3 x 16 bits.

This is the file you put in to Photoshop or Picture Window or your favorite editor for final adjustments - crop, size, sharpening, etc..

What about DNG ? Instead of the TIFF output from Vuescan, you can output it in DNG format, which probably (sorry that I'm unclear here) includes the RAW file together with your adjustments. I does not give you any extra quality - your previous RAW file has it all, and your TIFF-file has the RAW colour channels as adjusted by you, in a colour space that is your wanted one (typically Adobe RGB).

I would agree with this post.

The greatest advantage of saving a Vuescan scan as a RAW file would be to be able to reuse the Vuescan application, as opposed to Aperture/Lightroom/ACR to read the RAW file.

This might be worth the effort early in a scanning project when you were unfamiliar with Vuescan - you could save the RAW data and reprocess many times at your leisure, without having to physically rescan the slide or negative. One of Vuescan's greatest advantages over Nikon's old software is that it works in a two step process:

-- First it scans the medium to an intermediary file. Probably the most important thing is to remember to turn infrared cleaning "on." (You can turn it "off" later, but you can't use the IR channel if it is not recorded.)

-- Now comes the good part - you can go nuts with all of the filters/white balance, IR clean, etc., WITHOUT physically rescanning. (Contrast this with Nikonscan.)

Once you get things where you want, you can save in the format of your choice.

The only advantage that I see to saving a RAW file, is that you could repeat this latter step later. (Of course, you will be doubling your disk space and would have to set up some form of file structure to save the RAW files. But it might be a viable alternative to physically rescanning the slides or negatives. Could also be useful in allowing you to reprocess images with later releases of Vuescan - it updates about once a week. 😁

As far as cropping/retouching, etc., a TIFF gives you more latitude than a JPEG, so I saved everything to TIFF.

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DiploStrat 😉