Will Premiere import DPX 10-bit log scans without difficulty?

[Guy Burns]

I am having an 8mm film scanned on a Filmfabriek HDS+. See specs here. The output from the scanner can be either:

• DPX (10-bit log)

• Tiff (12-bit 444 Raw)

• AVI (8-bit Raw)

The operator outputs to DPX and then converts to a format of the customers choice. I was hoping to obtain ProRes 4444, but the operator is having problems with the conversion. On a short test film, ProRes blacks are clipped at 20% (when viewed in the RGB Parade), and look washed out when I import to Premiere.

I am absolutely certain that the original DPX files are quite okay.

So, I thought I should choose to go with the DPX files (10-bit log) direct from the scanner. If I do so, will I be able to import them into Premiere without difficulty? Or will they look washed out because they are log?

From what I read somewhere, Tiff would be an inferior choice because Premiere only handles 8-bit Tiff. Is that correct?

[R Neil Haugen]

Premiere can work with either the DPX or the Tiff files at their full depth at ingestion.

Log just means that the media has a totally linear contrast scale involved which typically of course gives the "flattened" low-contrast look when viewed in a non-adjusted state. It's very easy to either apply a corrective LUT or to manually adjust the contrast/saturation to return Log media to a 'normal' gamma-corrected state.

Just make sure you only use any color/tonal effects that are GPU accelerated and 32 bit float ... which are marked by their respective "lego blocks" in the Effects panel. So ... for color/tonal work, the Lumetri effect/panel is good as is the RGB Curves effect.

Some of the other "obsolete" color/tonal effects are 8 bit ... if you apply those, you drop the whole processing chain from 32 bit float to 8 bit. NOT what you want to do.

Neil

[Guy Burns]

Thanks for the response, Neil.

I'm not convinced, being a newbie to DPX, that it's going to be "very easy to apply a corrective LUT or to manually adjust the contrast/saturation". This brings up a few questions, which because I'm new to this, may not be sensible questions, and maybe I shouldn't be using DPX. This DPX-workflow PDF has almost completely put me off using DPX. It just looks so complicated. Still, it's all a learning experience. What I'm expecting to learn though, is that DPX is not for me.

Here goes anyway…

Ques 1

Inside a properly configured DPX file, is there information inside that file (LUT data?) that tells Premiere how to generate images on the timeline that look exactly as they looked on film? i.e. that the log encoding is reversed and made suitable for my iMac display. Or do I have to go looking for the "reversal data" and hope that I find the correct data?

Ques 2

A different way of asking Ques 1. I know that Premiere can generate ProRes files, but… if I import a DPX sequence, can Premiere generate a ProRes file in linear space (if that is the correct terminology) without me doing anything other than selecting ProRes 4444?

Choosing ProRes for export brings up very few options. The only option that seems to have any connection to "log" encodings is under Codec Settings which has one option of offer: Gamma Correction -- Automatic or None.

Ques 3

Does the export option Gamma Correction -- Automatic, automatically and correctly linearise a DPX when exported to ProRes?

[chrisw44157881]

a 10 bit log is about like a 12 bit linear, but Tiff is very nice, so I'd compare and zoom in the RGB parade to see which one is minutely better. if you went Tiff, at least you wouldn't have to play with the cineon effect log to lin to log again. later version of cc, 2018 and later, support 12bit dpx export. I know EXR is fully supported as 32bpc, so just do a quick test if 12 bit Tiff is not. (I'm pretty sure it is). The cineon converter effect has a lot of settings, so you'll need to ask them if they used full range or not and the gamma amount.

[R Neil Haugen]

"Normalizing" the contrast/saturation of log material isn't that difficult (compared to a lot of colorist work) ... but note, that is NOT doing a full grade. Just the returning to a visually "normal" and neutral/natural looking color/tonal state. Drop the darks/blacks, lift the whites, look for any contrast correction past that ... then adjust gross saturation and white balance/color cast correction.

Some of the LUTs provided for specific cameras by manufacturers had additional and often subtle per-channel color changes that many colorists puzzle out and apply via curves. I like reverse engineering them for the information ... but if you've not done much, you may prefer to simply use the camera maker's LUTs.

But you don't have a "normal" camera there ... you've got a scanner. That scanner may have a LUT the maker provides and if so, I'd certainly try it.

What GPU are you using, and if Nvidia, what is the driver? What setting for Mercury Acceleration in the Project settings panel?

Neil

[Guy Burns]

Mr Haugen     I haven't looked into the GPU, Nvidia, drivers and Mercury thing, but I can if it is essential.

Background     All scans below are taken from a test film, the only 8mm film I own, taken by a family friend in 1979. After the tests prove okay, I'll be asking the real film to be scanned, an historic 1969 film taken of a scientific survey of Lake Pedder, a beautiful lake that was flooded in 1972 for hydroelectric development. That's why I'm being picky about the scan.

Test Scans     I have obtained the DPX files for the test film and have uploaded several relevant items in the hope that someone more knowledgeable than me can work out what's going on. For the Pedder film, I'll probably be asking the operator to adjust levels in Resolve (his normal workflow) before he exports to ProRes 4444. But in the meantime, I want to find out why the operator using Resolve can do something that I can't do in Premiere, both of us using the same DPX files. This is a learning exercise and these are the downloads…

DPX Files – Ten files (171 MB) straight from the scanner. If you like 100 files (2GB), click here.

ProRes 422 Files – two excerpts of test files provided by the operator. On a PC he brought the scanner DPX files into Resolve, exported as Quicktime lossless, then used Abobe Media Encoder to export to ProRes.

• For the ProsRes file called Test Excerpt (orig) he made no changes.
• For the ProRes file called Text Excerpt (graded) he did a levels adjustment in Resolve before exporting.

RGB Parades  – two screen shots of RGB Parades on my iMac.

• RGB (422 graded) – the ProRes 422 graded video as seen in Premiere
• RGB (DPX) – the DPX video as seen in Premiere.

The Problem

When I bring Test Excerpt (orig), Test Excerpt (graded), and the DPX files into Premiere CS6, this is what I see:

• the DPX files and Test Excerpt (orig) are washed out and have flat bottoms in RGB Parade
• Test Excerpt (graded) looks fine. Remember it's not really graded, just levels-adjusted in Resolve.

No matter what RGB Curves adjustments I make in Premiere to the DPX files or Test Excerpt (orig), I cannot obtain anything that looks as good was what the operator obtained by adjusting levels in Resolve.

If anyone has the time to download and import the three video files into Premiere, I'd be very interested to find out if you can make the DPX files and Test Excerpt (orig) look the same as Test Excerpt (graded). I'd especially like to see that flat bottom go away.

Thank in advance to anyone willing to help.

[Richard M Knight]

The colour tools in a newer version of Premiere might give you results nearer to Resolve. 

[R Neil Haugen]

Like Richard says, I think you'll need to use a later version. And I'd be happy to test.

Neil

[Guy Burns]

I may not have been clear about what I meant by RGB Curves adjustment. I am not adjusting colour in these tests, just the contrast – by altering the Master black slider and the Master white slider. I am not trying to match colour at this stage, I am trying to match the dynamic range.

Basically: the untouched DPX files out of the scanner, and when put through Resolve and Adobe Media Encoder and converted to ProRes 422 (once again, untouched), come to me looking sus. But when the levels are adjusted by the operator (no fancy colour grading) the ProRes 422 files are okay at my end. ProRes 4444 should be even better.

I don't understand how the operator, in Resolve, can remove what appears, in my Premiere, to be clipping at the bottom of the DPX files, when I can't do it in Premiere. Maybe it has something to do with the 10-bit log DPX files not being interpreted properly by my Premiere. If someone can download and drag the DPX files to a timeline inside a recent Premiere, and the bottoms are not clipped, then it will be proven that my Premiere is lacking.

[chrisw44157881]

near as I can tell, the dpx starts off at 30 ire. you can match them with a simple curves adjustment.

now CS6 had curves, i think. but the math of them was a little different if I remember correctly. you could try transfer modes to customize your curve's math. transfer modes are in opacity.

Make 3 adjustment layers in a sandwich and set their transfer modes to the following:
1. normal
2. multiply
3. normal

on all 3 layers, use curves and raise the midtones up. don't touch the black. 

if you play around with it, it should give you the equavalent of a shadow plugin.

short of this, the only people that can be 100% sure this will work are people that still have CS6 installed.

[R Neil Haugen]

One of the issues for using CS6 is that most of the color tools are simply 8 bit. That's of course drastically different in the current version, as a couple of the old color/tonal tools that are still included in the 'obsolete' effects folder were eventually upgraded to 32-bit float, but note ... even they are in the 'obsolete' folder.

I've no clue if when you drag the say blacks end-point of the RGB curve if the bottom is changing position or not. From your comments, I've no way of knowing at all what the behavior is.

So ... testing the media on my rig with a newer version would be informative.

Neil