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White Balance/Color Space Questions on VueScan DNG & TIFF Files

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After reading both the User's Guide and The VueScan Bible, I am now trying to set up VueScan to give me files that I can both use as digital masters and for any post-processing in LR. The issue that I am trying to better understand is how VueScan's raw file in DNG format differs from an outputted TIFF file with respect to White Balance in LR. The DNG raw file shows me the standard White Balance options for a raw file with the temperature scale displaying the color temperatures. The TIFF file that was outputted shows me the scale that is used with jpeg files and displays a scale from -100 to +100. This makes full sense to me if I was working with a raw and jpeg files from a camera, but I am a bit uncertain about what I am actually gaining from VueScan's DNG raw file format with respect to white balance. Is this file more malleable (like a raw file) when it comes to setting white balance, or is it just displaying the color temperature scale because the file is in DNG format, and it doesn't actually offer me any more leeway that the TIFF output file? I know that the Color Balance setting in VueScan on the Color Tab seems to impact one of the two files (the TIFF I am assuming) as they appear different. I have no objections to working in the DNG format for the master file, but TIFF is a bit easier if I end up sharing the files with people.

Also, one related question regarding Output Color Space. The usual choices are available (including sRBG, Adobe RGB and ProPhoto RGB). I am normally used to working with raw camera files that have no assigned color space and I just assign a space to any derivative file on export, but I am not sure what would be a good color space to assign to these files. I plan on processing them in LR, but they are also master files and it would be nice (but not absolutely necessary) if they were readable outside of LR should they be shared without any LR processing.

Any thoughts?

--Ken
 
I'm not sure what VueScan is creating as an output image file. DNG can contain RAW data or it can Contain an RGB image in the data block. RAW data has not color space since it in not RGB data and will not get a colorspaces assigned until converted to RGB. With TIFF you will always have RGB data in the data block. Further, the DNG standard is based on the TIFF/EP6 standard.

An RGB image file must have a color space assigned and used to define the limits of the color pixels. IF your DNG output file requires a Color space choose the largest gamut available.

Lightroom Classic will always use ProPhotoRGB and Photoshop can use ProPhotoRGB as a Working colorspace.

For Exporting you need to create a derivative idol in the colorspace for the output medium. For scree the generic sRGB color profile is used but more and more monitors are AdobeRGB capable. However Browsers will often limit to sRGB on display. For Prints,you should assign the generic AdobeRGB to a specific color profile to match the printer and the paper to be used. You would always want to use. the widest gamut for the job noting that any color pixels that fall outside of the color gamut of the media may not display well.
 
When we talk about ‘raw data’, we usually mean the kind of raw data that are produced by a camera with a Bayer filter, so data that still have to be demosaiced. A scanner does not produce that kind of data, because it uses a linear CCD with three rows of pixels, one row for each color. The CCD moves along the image, so the scan will contain full RGB data for each pixel. You can still have ‘raw’ data in this case, but these are like the ‘raw’ panorama DNG files that Lightroom can produce.
 
IF your DNG output file requires a Color space choose the largest gamut available.

Lightroom Classic will always use ProPhotoRGB and Photoshop can use ProPhotoRGB as a Working colorspace.

For Exporting you need to create a derivative idol in the colorspace for the output medium. For scree the generic sRGB color profile is used but more and more monitors are AdobeRGB capable. However Browsers will often limit to sRGB on display. For Prints,you should assign the generic AdobeRGB to a specific color profile to match the printer and the paper to be used. You would always want to use. the widest gamut for the job noting that any color pixels that fall outside of the color gamut of the media may not display well.

Hi Cletus,

I had considered saving the TIFF file with ProPhoto RBG as it is what LR uses, but as I almost always work with raw camera files that have no color space assigned, I did not if there was a file difference in data if VueScan saved the file in ProPhoto vs AdobeRGB, for example, or if the assignment of a space was just a matter of convenience. I do export all derivatives into the appropriate color spaces (usually sRGB) so there is no confusion when they are used by others.

--Ken
 
When we talk about ‘raw data’, we usually mean the kind of raw data that are produced by a camera with a Bayer filter, so data that still have to be demosaiced. A scanner does not produce that kind of data, because it uses a linear CCD with three rows of pixels, one row for each color. The CCD moves along the image, so the scan will contain full RGB data for each pixel. You can still have ‘raw’ data in this case, but these are like the ‘raw’ panorama DNG files that Lightroom can produce.
Hi Johan,

This is kind of what I was wondering. In this case, does this "raw" DNG file actually then have a color space? And is the really any difference in how the White Balance temperature reads with respect to IQ when making the adjustment? For example, in a real camera raw file, the white balance temperature is not fixed and can be adjusted by the user using the color temperature scale. With a jpeg, the white balance temperature is fixed, and while the image can be "adjusted" (-100 to +100), the user is not actually changing the white balance color temperature. I may be "changing' the WB temperature on the DNG file because that is the scale that LR provides me, but in reality it is not different than if the other scale (-100 to +100) was provided and all I was doing was making an adjustment to the file like a jpeg since this is not raw data from a sensor.

--Ken
 
Hi Cletus,

I had considered saving the TIFF file with ProPhoto RBG as it is what LR uses, but as I almost always work with raw camera files that have no color space assigned, I did not if there was a file difference in data if VueScan saved the file in ProPhoto vs AdobeRGB, for example, or if the assignment of a space was just a matter of convenience. I do export all derivatives into the appropriate color spaces (usually sRGB) so there is no confusion when they are used by others.

--Ken

I hope that you are not thinking that the DNG format from the VueScan is RAW photosite data. As Johan has indicated that it is RGB pixel data in a DNG wrapper.


Sent from my iPad using Tapatalk
 
I hope that you are not thinking that the DNG format from the VueScan is RAW photosite data. As Johan has indicated that it is RGB pixel data in a DNG wrapper.


Sent from my iPad using Tapatalk
No, I know better than that. But, I did not know if what "raw" data from a CCD sensor exactly looked like, and Ed Hamrick's explanations are not that helpful. But, as I touched upon in my response to Johan, it does make me wonder what causes LR to offer up one white balance scale vs. the other. I can understand a camera raw vs. a jpeg, but if one puts this scanner "raw" file (a TIFF) in a DNG wrapper, is that enought for LR to offer up the same temperature scale that it offers up with camera raw files? And how does that scale and operation differ from the scale that it offers up for jpeg files?

In short, is there any benefit to outputting these DNG "raw" files rather than just plain TIFF files for post processing in LR, especially when it comes to correcting faded or shifted prints? The White Balance dropper seems like the ideal tool to address this issue, but perhaps there is another method that I am not considering?

--Ken

P.S. Bridge shows the DNG "raw" files as untagged. And EXIFTool (GUI) says that these files are 16/16/16 linear raw.
 
I don’t know all the technical details, but these files could indeed be raw, meaning they are the pure sensor data. The fact that these data contain values for R, G and B does not make that impossible. Raw files from a Foveon/Sigma sensor also contain R, B and B values, and still they are raw. They will definitely be linear, because sensors are linear. I’m not sure what this means for the white balance, but panorama DNG files also do not seem to have a white balance yet.
 
Perhaps you already know this, but among the advantages of using DNG - like any RAW file - is that you can always start over from the beginning, with no losses (other than your settings, of course), since the files are never locked down. I've gone back to images I took 15 years ago and improved them to an amazing degree. LR and many kinds of software get better every year, the computers get faster, and practice helps, too.

If you are comfortable with HDR, you can make virtual copies of a DNG, process them three different ways, and combine, in order to get a remarkable amount of dynamic range. You can, of course, do this with any file, but DNGs allow a lot more latitude.

As for printing, I've printed many times directly from a DNG to my Canon printer with great results. Both my monitor and printer have been profiled, which makes that possible. For images that will be printed by someone else, I'll output as sRGB JPGs at 300 ppi and that works very well.
 
Perhaps you already know this, but among the advantages of using DNG - like any RAW file - is that you can always start over from the beginning, with no losses (other than your settings, of course), since the files are never locked down.
That is the same for any type of image in Lightroom. Lightroom edits are non-destructive, regardless of the file type.
 
The info below is not definitive, but just some of my conclusions from using VueScan for many years:

VueScan raw: Just to be clear, even though some VueScan users here might already know this, VueScan has a "raw" scan option that predates camera raw formats and is not the same. In VueScan terminology, a "raw" scan means no VueScan processing is applied, and it’s an RGB image since it’s a scan, not camera raw sensor data. The nice thing is you can reload a VueScan raw into VueScan and then apply its processing settings, as if you were scanning the original. So you can do things like scan to VueScan RGB raw + the infrared defect channel (4 channels total), walk away for a week, come back, load up that file, and process it including hardware-based defect removal without the scanner even being present. Basically, VueScan "raw" allows reprocessing without having to rescan.

VueScan raw vs DNG: VueScan raw is an RGB TIFF with no processing applied, VueScan TIFF DNG is a TIFF in a DNG wrapper. The TIFF will come into Lightroom Classic with White Balance defaulting to 0 (As Shot) like a JPEG, but the DNG shows a default white balance of Temp 6500K Tint +10, like a raw file. I do not know if that’s because I usually set VueScan white balance to Neutral because I want to make the adjustment in Lightroom Classic, but I interpret that as VueScan assuming a scan was shot with daylight balanced film. I am not technically sure if there is any difference in how white balance is recorded, but anecdotally, I've moved to DNG because I thought the white balance adjustments in Lightroom Classic looked better if I saved from VueScan as DNG, especially for old film with uneven fading that misleads white balancing algorithms. But this needs more objective testing.

Color space: By default I don’t think a VueScan scan has a color space, since a scanner sensor doesn’t match up with any of the standard ones like sRGB. I see the Output Color Space option in the Color tab as working like the Color Space option found in Lightroom Classic Export options or the Adobe Camera Raw Workflow/Save options. In other words, it is a profile assigned to and embedded into the final saved image file. (A VueScan scan can have a default color space if you have profiled the scanner and loaded that profile into VueScan using the Scanner ICC Profile option in the Color tab; in that case I believe VueScan would instead assign the scanner profile to the scan while you work on it in VueScan, and then convert the scan to the Output Color Space profile on the way out.)

Also, one related question regarding Output Color Space...I am not sure what would be a good color space to assign to these files. I plan on processing them in LR, but they are also master files and it would be nice (but not absolutely necessary) if they were readable outside of LR should they be shared without any LR processing.
Personally I set the Output Color Space to ProPhoto RGB because they’re film scans that I save as 16 bits per channel, because I want to get as much color quality as I can off the film. But it is possible that Adobe RGB would be just fine, especially if they were all scans of prints from a commercial (not pro) lab being saved as 8 bits per channel. In other words, it depends on the color range of the originals being scanned and the quality of the scanner’s sensor; if you think both can represent a wide color gamut you’re more likely to want to use ProPhoto RGB. Like if you were using a very good scanner on a pro lab print. But I haven’t looked into, for example, the potential color gamut of a Cibachrome vs. consumer Kodak print vs. color negative film like Portra.

If it’s a family archive mostly shot on consumer film and papers, and you want it to be immediately shareable, then sRGB would be fine. But to support being shareable by any family member using simple photo software, you would probably also want the scans saved as TIFF or JPEG rather than DNG. If you go that direction, then it follows that you want to get good at having VueScan process the scans to be acceptable quality without further processing, in case they get shared as is outside of Lightroom.
 
If you are comfortable with HDR, you can make virtual copies of a DNG, process them three different ways, and combine, in order to get a remarkable amount of dynamic range. You can, of course, do this with any file, but DNGs allow a lot more latitude.
The data inside the DNG determine the dynamic range, not the DNG wrapper.
 
Perhaps you already know this, but among the advantages of using DNG - like any RAW file - is that you can always start over from the beginning, with no losses (other than your settings, of course), since the files are never locked down.
While true, that doesn’t apply to a VueScan+Lightroom discussion because DNG is not necessary to be able to start over with that workflow.

As stated above, if you wanted to be able to "re-scan" in the future, possibly with different settings, without actually having to rescan, you use VueScan raw format, and you now have nondestructive reprocessing. And with Lightroom, any format gets nondestructive processing, so you can also start over at any time from that perspective. The question we’re working through here is, what difference does DNG make specifically within a scanning workflow involving VueScan going to Lightroom?
 
I don’t know all the technical details, but these files could indeed be raw, meaning they are the pure sensor data. The fact that these data contain values for R, G and B does not make that impossible. Raw files from a Foveon/Sigma sensor also contain R, B and B values, and still they are raw. They will definitely be linear, because sensors are linear. I’m not sure what this means for the white balance, but panorama DNG files also do not seem to have a white balance yet.
I am still researching this and have come across a number of discussions about VueScan's "raw" file options. I am not nearly done with the reading, but a theme is starting to appear. The advice being offered is to just save a standard 48-bit TIFF file in ProPhotoRGB. Unless you are planning to run the raw files back through VueScan, which was probably the primary point of the file format so a physical re-scan is not needed, then the value in a program like LR sounds quite limited.

More to the point about LR, it does make me want to know more about the different modes of White Balance and how they differ, or if they differ at all (I.e. just the scale changes from color temperature to -100/+100, but the file type drives the results, not a change in the behavior of LR).

--Ken
 
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While true, that doesn’t apply to a VueScan+Lightroom discussion because DNG is not necessary to be able to start over with that workflow.

As stated above, if you wanted to be able to "re-scan" in the future, possibly with different settings, without actually having to rescan, you use VueScan raw format, and you now have nondestructive reprocessing. And with Lightroom, any format gets nondestructive processing, so you can also start over at any time from that perspective. The question we’re working through here is, what difference does DNG make specifically within a scanning workflow involving VueScan going to Lightroom?
Bingo!

--Ken
 
I forgot to mention that in the VueScan Help page for the Color tab, the description for the Output Color Space says:
The Output color space is used when writing images to JPEG, TIFF, PDF and Index files.
If that’s up to date, then it means no color space is assigned to a VueScan DNG file, I guess? So Lightroom Classic would just bring it in, assume the color is “mystery meat” (color management technical term for an untagged image :) ), and assign its internal color space (Melissa RGB) for editing.
 
While it is true that Lightroom editing is always non-destructive, if you want to re-process an image from the beginning in any other editor - and there are a large number of other ones, and growing, then having a DNG at your disposal enable this. As a professional photographer, it is super important that I maintain flexibility in my images, including, in particular, my legacy images, since they may be used for secondary licensing, or even simply printing or posting on my portfolio website. Having read this, I do approximately 80% of my work in LR, and have often delivered DNGs that were exported as JPGs without ever leaving LR.

As for HDR processing using 3 copies of the same image, images can get really ugly trying to push a single image around, where working on highlights and shadows in copies or virtual images on "either side" of the original image can make all the difference. And it's super easy to do. This of course does not work using LR HDR, but works great using plugins, such as Enfuse. Again, as a professional, I have to deliver a good image no matter what, and anything that increases my capabilities is a good thing. The clients don't care how I get there, they just want what they are paying for.
 
Barry, if working this way gives you an advantage, then by all means do that. But don’t believe in micracles. Merging three edits of the same raw image does not increase the dynamic range. The resulting ‘HDR’ will have the exact same dynamic range as the original.
 
There's no miracle here. It works for me because the primary plugin I use, Enfuse, allows me to do extreme editing on each image and still blend them together. For instance, I can use a brush to change anything, change the temperature and clarity and noise reduction globally, all kinds of things, and get results that otherwise would require me to export three TIFs, then reimport them back into LR, and then do HDR. This way, I can quickly blend three images and get a good result. Typically, I don't have work on copies of the same image, since I typically bracket my shots, but if there are plants or trees and any wind at all, I'm going to have big problem getting blends using any HDR software of any kind.

While mostly shoot architecture, I also do documentary work and portraits, often cannot light, and those subjects are not stock-still, meaning I cannot bracket, so this process is critical to getting a good result.

Time is money (and can equal emotional stress!). Even more, I can make multiple attempts to get a good image without leaving LR until I get it right. No less, you can push around the pixels in a RAW file in ways that won't work as well in a TIF or PSD (which is what I process my architectural images in). I shoot a 5D S R, which produces a 50 MGB file, which is reasonably large. Even using my late-model, jacked-up MacBook Pro and viewing on a monitor, when the DNG is exported as as TIF or PSD, I'm looking at 300-400 MGB 16-bit file, so working with a smaller file is a lot easier and faster. This workflow may not work for everyone, but I do virtually all my own post, so it works for me.
 
I’m sure this workflow suits you, and I have no comment on the workflow itself. But it has nothing to do with DNG. DNG is just a wrapper. It’s like an envelope. What matters is the letter inside, not the envelope. A JPEG that is exported from Lightroom as a DNG is still 8 bit data, wrapped in DNG. Same for anything else you wrap in DNG.
 
I forgot to mention that in the VueScan Help page for the Color tab, the description for the Output Color Space says:

If that’s up to date, then it means no color space is assigned to a VueScan DNG file, I guess? So Lightroom Classic would just bring it in, assume the color is “mystery meat” (color management technical term for an untagged image :) ), and assign its internal color space (Melissa RGB) for editing.
I am thinking that we may need to establish a new RGB in your honor called CCMMRGB (Conrad Chavez's Mystery Meat RGB) for those special occasions! ;)

I did do more research, but first your post does raise the question of how much color gradation is lost if I decide to use a regular TIFF format and assign a color space like AdobeRGB instead of ProPhotoRGB if my exported derivatives will mostly be sRGB jpeg files?

I did finish reading all of the materials that I decided to look at and I think that this thread best sums up the discussion at hand on the various VueScan file formats - Vuescan File Formats: "RAW DNG" vs. "TIFF DNG" - Rangefinderforum.com . It is quite an interesting read, and it leaves me leaning toward outputting a plain, 48-bit TIFF file. My assumptions are that regardless of which LR White Balance scales I get (color temp vs -100/+100), the impact is going to be the same regardless of VueScan's TIFF/Raw/DNG options because this is not a true raw file. And, I am not really interested in reprocessing the file in VueScan later so keeping it in a file format for that purpose has very little value to me.

But, that does raise the final question of whether I should let VueScan set both the Black/White points and the color balance before generating the TIFF file. I would prefer to do this work in LR, but I am not sure if it is better to do these upstream.

--Ken
 
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Perhaps you already know this, but among the advantages of using DNG - like any RAW file - is that you can always start over from the beginning, with no losses (other than your settings, of course), since the files are never locked down. I've gone back to images I took 15 years ago and improved them to an amazing degree. LR and many kinds of software get better every year, the computers get faster, and practice helps, too.
Is it also possible to treat a scanner TIFF file as the "negative" and perform non-destructive edits?

To generalize my question, how much additional value is there for a scanner RAW file as opposed to a scanner TIFF file?

If you are comfortable with HDR, you can make virtual copies of a DNG, process them three different ways, and combine, in order to get a remarkable amount of dynamic range. You can, of course, do this with any file, but DNGs allow a lot more latitude.

As for printing, I've printed many times directly from a DNG to my Canon printer with great results. Both my monitor and printer have been profiled, which makes that possible. For images that will be printed by someone else, I'll output as sRGB JPGs at 300 ppi and that works very well.
 
Personally I set the Output Color Space to ProPhoto RGB because they’re film scans that I save as 16 bits per channel, b

Scanners are like any other RBG device in that the color measurements are unique to each device. So in order to get the most accurate color rendition from you scans you will need to create a device specific color profile. This is possible only for color pictures (reflective) or slides (positive film).

There are a number of scan targets available from places like Chromix.com that can be used for this purpose. Using any of these will be better than simply assigning a random color space. If I were to simply assign a color space I would be inclined to use either sRBG or Adobe RGB as the gamut is going to be closer to the gamut of the scanner.

Unfortunately it is not possible to profile color negative film due to the orange mask. This is why for example VueScan includes an extensive library of "Film Types" that help make appropriate corrections.

-louie
 
Scanners are like any other RBG device in that the color measurements are unique to each device. So in order to get the most accurate color rendition from you scans you will need to create a device specific color profile. This is possible only for color pictures (reflective) or slides (positive film).

There are a number of scan targets available from places like Chromix.com that can be used for this purpose. Using any of these will be better than simply assigning a random color space. If I were to simply assign a color space I would be inclined to use either sRBG or Adobe RGB as the gamut is going to be closer to the gamut of the scanner.

Unfortunately it is not possible to profile color negative film due to the orange mask. This is why for example VueScan includes an extensive library of "Film Types" that help make appropriate corrections.

-louie
Color fidelity can truly be the rabbit hole of rabbit holes at times! I would never deny color fidelity's importance, although I admit to being slow at re-calibrating my monitors sometimes, but some days it seems like the choices and options never seem to end. I had assumed, and I believe that Cletus also suggested, that it would be advisable to select a large color space like ProPhoto as a working color space for the files I am creating since they will be processed in LR. But, I am not sure how to reconcile that with your suggestion to pick a color space as close to the gamut of the scanner, which also seems advisable.

I have spent the better part of the past few months trying to establish a reasonable work flow for this project, and it seems like every time I think that I have all of the boards nailed down, one seems to either pop up or appear loose. What is completely ironic is that while I believe in trying to achieve the best color fidelity possible, I am also struggling with how I should be presenting the photos that I have scanned. Some have faded, some are tinted, some may need color restoration and some are a combination of all of these issues. I keep looking at the B/W test image I am using which has a very slight sepia tone to it (most likely from aging), and I cannot decide if it is better to present it as such or use use white balance tools to make it look white (again?). In short, unlike an image that I shot and know what it should look like, or what I want it to look like, I am having to make decisions about images that I have no knowledge of with respect to color fidelity.

I was hoping to do the best I could given the materials I am working with (as there are limits to what can be extracted from old photos) to make some digital master files for the family, without regretting my technical choices in the future, but I am starting to wonder which decisions will prove to be more material than others. This situation reminds me of an expression that a wise person once shared with me - ignorance is bliss, no wait, I meant to say that ignorance was bliss. I am not ignorant of color fidelity, nor do I wish to be, but being aware of all of the possible choices for this project is anything but blissful.

--Ken
 
Scanners are like any other RBG device in that the color measurements are unique to each device. So in order to get the most accurate color rendition from you scans you will need to create a device specific color profile. This is possible only for color pictures (reflective) or slides (positive film).

There are a number of scan targets available from places like Chromix.com that can be used for this purpose. Using any of these will be better than simply assigning a random color space. If I were to simply assign a color space I would be inclined to use either sRBG or Adobe RGB as the gamut is going to be closer to the gamut of the scanner.
I was thinking more about this after my post. VueScan asks you to set a scanner space color (either Default or a custom ICC profile) as well as set the output color space, so if my thinking is correct, then it should not necessarily be a bad idea to export into a large color space as VueScan does have some point of reference as to the scanner's working color space before it assigns the export profile. Ideally it would great if I created my own ICC profile, but assuming the Default that VueScan offers is reasonable, is there something that I am not considering here?

--Ken
 
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