GH5 to Alexa Conversion

[heart0less]

@Maxbrand, wow!

These stills look gorgeous. 

[Sage]

10 hours ago, Maxbrand said:

I find that using the pre and then working as if I had shot in V-log works very well when using HLG. I was somewhat forced into this workflow when I bought the Ninja V because of the whole video levels thingy making v-log impossible to use if you want a reliable preview on the monitor. I find HLG more or less as good anyway though, so doesn't really matter much to me.

Some examples of using HLG with GhA:

They look great. Could you share the original HLG still of this one?

[thebrothersthre3]

Hey Sage what do you do to achieve the highlight roll off seen in your lut? Say if I am using adobe premiere? Is it a curve adjustment? 

[Sage]

EC was made by filming a large number of color samples with both cameras, and then extracting coordinate data from those samples and supplying that data to a my own c++ program. As channel clipping occurs, the program attempts to straighten hue lines to follow that of the higher DR camera. There is a point at which those hue lines merge during clipping, such that clipped red is identical to yellow, for example. When these regions are detected,  they are reduced to near grayscale data:

[Attila Bakos]

1 hour ago, Sage said:

EC was made by filming a large number of color samples with both cameras, and then extracting coordinate data from those samples and supplying that data to a my own c++ program. As channel clipping occurs, the program attempts to straighten hue lines to follow that of the higher DR camera. There is a point at which those hue lines merge during clipping, such that clipped red is identical to yellow, for example. When these regions are detected,  they are reduced to near grayscale data:

Oh yes, this is the kind of detail that excites me   Keep them coming. Too bad I can't scroll that still image ?
I've chosen not to deal with hue shifts in my own conversions, but in your situation where one camera has way more DR than the other, it seems like something that can't be ignored.

[RCV]

On 3/19/2019 at 11:58 AM, Maxbrand said:

I find that using the pre and then working as if I had shot in V-log works very well when using HLG. I was somewhat forced into this workflow when I bought the Ninja V because of the whole video levels thingy making v-log impossible to use if you want a reliable preview on the monitor. I find HLG more or less as good anyway though, so doesn't really matter much to me.

Some examples of using HLG with GhA:

 

 

 

 

 

Man! Really great work!!  Im interested in this particular frame! What was the white balance? Is the Blue hue post color work? If so what version of the lut did you use as base?

[Sage]

22 hours ago, Attila Bakos said:

Oh yes, this is the kind of detail that excites me   Keep them coming. Too bad I can't scroll that still image ?
I've chosen not to deal with hue shifts in my own conversions, but in your situation where one camera has way more DR than the other, it seems like something that can't be ignored.

For the c++, there is a problem I'm trying to solve. Giant 4D arrays aren't supposed to be declared on the stack like this, but I haven't figured out how to conveniently pass them to functions any other way yet (vector pointer 'arrays' can only be 2D etc)

[Attila Bakos]

2 hours ago, Sage said:

For the c++, there is a problem I'm trying to solve. Giant 4D arrays aren't supposed to be declared on the stack like this, but I haven't figured out how to conveniently pass them to functions any other way yet (vector pointer 'arrays' can only be 2D etc)

Wish I could help with C++. I use Matlab for my stuff and it's pretty convenient. If I didn't have access to it I think I would use Python.

[kye]

On 3/22/2019 at 8:45 PM, Sage said:

For the c++, there is a problem I'm trying to solve. Giant 4D arrays aren't supposed to be declared on the stack like this, but I haven't figured out how to conveniently pass them to functions any other way yet (vector pointer 'arrays' can only be 2D etc)

It's been a long time for me, but I remember just passing a pointer and then navigating the data structure as required.  Oh the days of writing double-linked-list databases

[Sage]

6 hours ago, kye said:

It's been a long time for me, but I remember just passing a pointer and then navigating the data structure as required.  Oh the days of writing double-linked-list databases

The part that I'm stuck on is how one would navigate a multi dimensional array from the pointer. For example, is there any way to do something like array * [3][14][7][12]?

On 3/22/2019 at 11:47 AM, Attila Bakos said:

Wish I could help with C++. I use Matlab for my stuff and it's pretty convenient. If I didn't have access to it I think I would use Python.

Someday, I want to learn Python. I've got to master c++ first though. I just bought Stroustrup's Tour of c++ book

[jase]

Shot this using GHa for CineD with my G9. Works quite well after some exposure adjustments. Had to bring down the highlights quite a bit since I am more used to ETTR. Doesnt look as good as other examples within this thread, but I currently dont use any diffusion at all.

[Jonesy Jones]

@Sage, how certain are you that you will be creating your lut for the P4K? The colors for the gh5 are so good that I am constantly tempted to keep it instead of the p4k. 

I don't know how you'd feel about this, but since I have both I wonder if I could shoot with both cams to create a temporary fake gha lut until yours comes out.

[Sage]

100% certain; I would call it the #1 camera. Expect something soon; that said, can you live without IBIS? I think I will keep both

5 hours ago, jase said:

Shot this using GHa for CineD with my G9. Works quite well after some exposure adjustments. Had to bring down the highlights quite a bit since I am more used to ETTR. Doesnt look as good as other examples within this thread, but I currently dont use any diffusion at all.

Stunning! Wouldn't have thought a G9 would look so good, like no G9 I've seen

[jase]

Thanks Sage. I got a question about exposing with CineD. You write:

Quote

"Skin tone should fall roughly between 40 and 55 IRE (HLG 26-55, Cine-D 28-57). Avoid allowing skin tone below 40, or above 60 (HLG 66, Cine-D 72). The rolloff occurs above 65 (HLG 77, Cine-D 84) - this is for over-bright elements."

So what I do is setting my Zebra to 55% and expose for the skintones - secondary I check whether the scene wouldnt be completely blown out. Is this somewhat correct or am I missing something?

[Maxbrand]

On 3/21/2019 at 6:19 PM, RCV said:

Man! Really great work!!  Im interested in this particular frame! What was the white balance? Is the Blue hue post color work? If so what version of the lut did you use as base?

Thanks! Actually I just ignore a lot of the stuff that Sage writes in the white paper. For example here I had white balance at something like 4000 and a light bulb with 6000k WB, nothing is done to it other than using the excellent GhA-LUT. Mostly this decision is because I seldom get the benefit of grading the things I shoot, and therefore I try to do as many decisions as possible in camera so that the people in post don't do their own version of it.

I'm happy that you took this frame specifically because it is lit only with a cheap e27 LED light bulb from the hardware store for something like 8€ and their phone screens that I made them turn up to maximum. This whole short was done in like 6 hours and I went with a lighting style that was super simple, quite fun to try to figure out different looks in the same room in a short amount of time!

 

On 3/20/2019 at 3:11 AM, Sage said:

They look great. Could you share the original HLG still of this one?

Thanks! Here you go! I remember now that I added some contrast as well after your LUT. But that's all.

HLG_1.8.1.dpx

[RCV]

15 hours ago, Maxbrand said:

Thanks! Actually I just ignore a lot of the stuff that Sage writes in the white paper. For example here I had white balance at something like 4000 and a light bulb with 6000k WB, nothing is done to it other than using the excellent GhA-LUT. Mostly this decision is because I seldom get the benefit of grading the things I shoot, and therefore I try to do as many decisions as possible in camera so that the people in post don't do their own version of it.

I'm happy that you took this frame specifically because it is lit only with a cheap e27 LED light bulb from the hardware store for something like 8€ and their phone screens that I made them turn up to maximum. This whole short was done in like 6 hours and I went with a lighting style that was super simple, quite fun to try to figure out different looks in the same room in a short amount of time!

 

HLG_1.8.1.dpx 7.92 MB · 0 downloads

Thats freaking amazing! I am going to experiment with shooting 4000 in daylight witht he GhA. I use to shoot  4200  in Daylight for those bluish hues or 7000 for the yellowish golden tones but reading the document had me apprehensive. I'll definitely do my tests

 

 

.

 

On 3/24/2019 at 4:57 PM, jase said:

Shot this using GHa for CineD with my G9. Works quite well after some exposure adjustments. Had to bring down the highlights quite a bit since I am more used to ETTR. Doesnt look as good as other examples within this thread, but I currently dont use any diffusion at all.

looks better than some gh5 vids on youtube! great stuff

[katlis]

On 3/25/2019 at 5:36 AM, Maxbrand said:

I'm happy that you took this frame specifically because it is lit only with a cheap e27 LED light bulb from the hardware store for something like 8€ and their phone screens that I made them turn up to maximum. This whole short was done in like 6 hours and I went with a lighting style that was super simple, quite fun to try to figure out different looks in the same room in a short amount of time!

Nice, I recently shot a similar scene with a cheap Neewer LED (blue gelled) bounced off the ceiling and an LED stick inside the window. Face was just lit with the phone! Loving the GH5S, this was shot at 5000 ISO. Grading started with GHAlex and then a bunch of other adjustments as you can see. ?

[Sage]

On 3/25/2019 at 2:30 AM, jase said:

Thanks Sage. I got a question about exposing with CineD. You write:

So what I do is setting my Zebra to 55% and expose for the skintones - secondary I check whether the scene wouldnt be completely blown out. Is this somewhat correct or am I missing something?

Sure; from what I've seen, the G7 had a notably higher gamma curve than the GH5 in Cine-D, all things being the same. I corrected this with a hue-locked downward gamma shift in advance of the conversion. I don't know if this is the same for the G9, but your description of working with it seems to suggest this may be the case. Your results are quite good. There were just a few points of rougher rolloff that I would expect from a reference GH5 pipeline.

On 3/25/2019 at 5:36 AM, Maxbrand said:

I had white balance at something like 4000 and a light bulb with 6000k WB, nothing is done to it other than using the excellent GhA-LUT. Mostly this decision is because I seldom get the benefit of grading the things I shoot, and therefore I try to do as many decisions as possible in camera so that the people in post don't do their own version of it.

HLG_1.8.1.dpx 7.92 MB · 4 downloads

I'd recommend neutralizing the WB ahead of everything (even the Pre now), and then restoring the cast after everything. This will allow 'correct', clean Arri color underneath, and is the optimal route.

I took the dpx and did a slight initial WB from the white window frame in advance of the Pre, and then followed the conversion with a slight luminance drop to conform to day skintone. It was well shot:

By way of a silly example, here is a 'blue restoration':

[John Roque]

@Sage eagerly waiting for the XT3 version! I converted the flog to vlog first then added GHA. Is this the correct process? What do you guys think!?

[Adam Kuźniar]

8 hours ago, John Roque said:

@Sage eagerly waiting for the XT3 version! I converted the flog to vlog first then added GHA. Is this the correct process? What do you guys think!?

Looks good to me!