Shot Redspace, going to film out, NEED HELP UNDERSTANDING WHEN TO LIN INTO LOG

[John Tissavary]

Micheal, you're right - if HD or other linear medium is the primary delivery then Rec709 or some reasonably similar viewing space is the way to go.

Lucas - it's definitely not a trivial job to squeeze every single drop of goodness out of a Red filmout, and such a breeze to make stunning images with Scratch in linear.

But even though there are probably some complications when grading Red in log, my experience shows that applying the log conversion up front, then grading in a print emulation viewing environment ensures that the colorist has the most control to land the detail where it will 'line up' with the way film responds to light.

I am experimenting with the new raw log space in the Red node settings for a filmout in March - seems really promising. Can you elaborate some on exactly how this works?

cheers

John

[jake blackstone]

Autodesk did some testing with RED and had published a decent Lustre white paper on this subject.

[Steve Shaw]

Just as a point of note - You need a Film Calibration LUT for the process you are describing, and these have nothing to do with the source image at all...

Most (all?) film recorders assume the data they are going to be fed is 'Cineon/dpx Log'... If you present a tv gamma image (linear...), it is converted to Log via internal LUTs before the film-out process is performed.

So, the best way to approach a project that is going to be filmed-out, and you want to see an image that is accurate to the final film you need a 'film print' LUT, and then grade through that.

In this way you will 'push' the Red images into 'Cineon Log' space, ideal for the film-out.

Because of this, RedLog is the best way to go, with all other metadata turned off.

Does this help?

Have a look at the info on my website (www.lightillusion.com) to read more about this. The DI and Scene-to-Screen tech papers may be a good starting point.

Steve

[Steve Shaw]

Oh, and I should have added that you can then use a seperate LUT for any tv deliverables, matching them to the film look, but taking into acount the different viewing environment/monitoring...

Steve

[Antoine Baumann]

so why not have a lut that do linear light to log to print, so you actually see a "printed log" image while grading on the linear light?

, and these have nothing to do with the source image at all...

can you elaborate?

Thanks,
antoine.

[Viggenboy]

I just circled back on this thread and wanted to thank everyone for the input! In the end, we've taken a path pretty close to what Steve Shaw has suggested: Worked closely with the Lab who created an emulsion LUT for us using Cinespace. They factored in us working with Scratch going 444RGB into a Cinetal Cinemage, wide gamut. Its incredible how much the emulsion LUT alters the image.

In Scratch, (Before we knew about working with REDRAW LOG), we set the Red Color Space to Redspace, then used the RedLog Display LUT.

Then on the output of the DPX files, we baked in the Redlog LUT. I was always suspicious of this, not understanding what rendering that on top of rendering out Log DPXs would do. Was it potentially doubling the log curve? But we sent many DPX render tests to the Lab, and the fore-mentioned gave the best results.

We just saw our first film out test projected the other day, and the proof is in the pudding. Its impressive how much our image on the Cinetal is mirroring what the projected image ended up looking like.

So to those in the know, display and emulsion LUTs aside, if you take Red footage, (Linear), and render it out to Log DPXs, is that process applying a log gamma curve to the files in the render process?

We started this project on a certain path, but I'm looking forward to testing the same footage using RedRaw Log as the red colorspace. Partnering with a lab thats willing to test with us has been clutch.

Thanks again all.

[John Jonathan]

I just circled back on this thread and wanted to thank everyone for the input! In the end, we've taken a path pretty close to what Steve Shaw has suggested: Worked closely with the Lab who created an emulsion LUT for us using Cinespace. They factored in us working with Scratch going 444RGB into a Cinetal Cinemage, wide gamut. Its incredible how much the emulsion LUT alters the image.

In Scratch, (Before we knew about working with REDRAW LOG), we set the Red Color Space to Redspace, then used the RedLog Display LUT.

Then on the output of the DPX files, we baked in the Redlog LUT. I was always suspicious of this, not understanding what rendering that on top of rendering out Log DPXs would do. Was it potentially doubling the log curve? But we sent many DPX render tests to the Lab, and the fore-mentioned gave the best results.

We just saw our first film out test projected the other day, and the proof is in the pudding. Its impressive how much our image on the Cinetal is mirroring what the projected image ended up looking like.

So to those in the know, display and emulsion LUTs aside, if you take Red footage, (Linear), and render it out to Log DPXs, is that process applying a log gamma curve to the files in the render process?

We started this project on a certain path, but I'm looking forward to testing the same footage using RedRaw Log as the red colorspace. Partnering with a lab thats willing to test with us has been clutch.

Thanks again all.

You choose your color space when you conform. .R3D files can export DPX as RedLog, RedSpace, Linear etc.. 10bit Log to 16bit Linear. Thats where you choose your Colorspace. When you burn in a LUT you are not changing the colorspace per say, you are changing how it is seen. But Depending on how your LUT is working that can be a grey area.

But keep your colospace the same along the way and don't burn in your LUT unless you know exactly what you are doing and that is decided by the film printers. You need Rules and Method or you are just muddying the waters it's gonna make it harder for yourself to ever understand DI.

Your LUT is just your glasses, how you see the Footage. Leave the footage colorspace alone, grade and conform in that colorspace. Or at least convert LOG to LIN, Grade and use the exact LIN to LOG method to reverse it. Try to Leave in 16bit Linear or 10bit Redlog, and use your LUT glasses to see the footage correctly.

Also buy a book or hire support to walk you through it. You might have had a happy accident by taking 16bit Linear and filming out a REDLOG LUT and having it look right. Be careful because you might be in for a Big Spanking if you rules and methods are not correct.

Also Steve is a Quantel guy, he knows what he is talking about, but I think he thinks the Scratch is kinda a toy, where the iQ Pablo is the real tool.

[Rainer Fritz]

We had to finish three features last months graded on nucoda, baselight and lustre, i have to say first, and had problems to view the footage with the LUT which the labs using normally on their scans, when we were using Redlog, PDlog685 or PDlog985 -2 Stops.

So Steve what would you suggest, if we are not working on scratch, how to get first a LUT for the viewing environment to grade in log, with which red export settings?

For now we decided on the three projects and grading systems different ways. One way is to export in redspace/redlog from RED Raw to 10bit RGB DPX and grade linear full range, doing the lin/log conversion for filmout on the outgoing side of the grading system or on the ARRI laser direct. Same with redspace/PDlog685. This seems to give a good working base on grading, but a more videoish base look of the material....

So, but who can provide a LUT, where it is possible to match the viewing environment to the red footage, to the filmstock? A truelight LUT? So without a special LUT no way to grade in log ?

thx
rainer

[Evangelos Achillopoulos]

We had to finish three features last months graded on nucoda, baselight and lustre, i have to say first, and had problems to view the footage with the LUT which the labs using normally on their scans, when we were using Redlog, PDlog685 or PDlog985 -2 Stops.

So Steve what would you suggest, if we are not working on scratch, how to get first a LUT for the viewing environment to grade in log, with which red export settings?

For now we decided on the three projects and grading systems different ways. One way is to export in redspace/redlog from RED Raw to 10bit RGB DPX and grade linear full range, doing the lin/log conversion for filmout on the outgoing side of the grading system or on the ARRI laser direct. Same with redspace/PDlog685. This seems to give a good working base on grading, but a more videoish base look of the material....

So, but who can provide a LUT, where it is possible to match the viewing environment to the red footage, to the filmstock? A truelight LUT? So without a special LUT no way to grade in log ?

thx
rainer

We do that in a daily basis... read the link in my signature... the cost of it is the 1/10 of what Viggenboy payed for... all these questions are problems solved for us... we are a LAB that you can partner with and have the best results... all the comparisons that they have made for us (clients) with other Labs that are following the REC709 style were in our favor because a closed loop LUT Log workflow always gives the best velvet blacks with the best color rendition. The REC709 style is for kids play, the real DI is always Log.

I want to add something more in the Log or linear debate... Linear is clipping blacks and whites like video (even on film) and on the other hand Log has the regular film behavior (compressing blacks and whites)... So just by an artistic point of view Log is much better for grading, RED footage takes something from the magic of film response. And this is the reason of the videoish look... Linear workflow...

Beware that we don't partner with everyone there are rules that we follow to have the best post houses in terms of tech expertise and market share. There are regions like New York and Israel that we don't accept new partners in order to protect the existing ones.

[Harcharan Singh]

Hi,
Just digging into this old thread. Just wanted to know how things are being done with Red Color Science and Scratch 5.1 so that we can plan for an upgrade?How different it is from version 4.4?
Thks
Harcharan