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View Full Version : A hidden gem in cinema - Highlight Tone Priority



nickjbedford
12-14-2012, 03:36 AM
Just a curious thought that I've been having in regards to the difference between a high quality cinematic image and a low quality "video"-like image is that the highlights seem to always handled very graciously. This is a consequence of both the capabilities of the camera's sensor or film and the technique of the cinematographer choosing exposure.

It seems to me, that part of getting that cinematic, or "filmic", look is to do one of three things with your exposure and/or grading.


Roll off the highlights in grading so that clipped areas aren't obvious to even the trained eye, not unlike the way film is non-linear in the shadows and highlights.
Expose so that you can retain all that lovely highlight detail, and let obvious things like light sources (bulbs, etc) clip to a certain extent, which may also mean your subjects in a particular shot are down in the exposure (all normal decisions I've noticed in films).
Completely clip the bright area so that it acts basically as a giant light source in your composition. For example, if you're in a room and want to use the daylight as a back/key light, you have the external scene completely white or very very bright (due to exposure) and let it soak the room with light.


Thoughts? Of course this also comes back to effective raw (CinemaDNG) exposure for grading. Most of the time, you ideally want to be under the zebras with exception to visible light sources which will always clip, and sometimes you may need to expose not for the highlights, but for the subject of the shot and thus blow the bright areas.

I've noticed that some of these more "video" centric cameras (FS700) are not exposed well or simply don't have enough dynamic range and their skies or reflections clip very obviously. Skies that are blue then become an ugly aqua colour very quickly then white.

nickjbedford
12-14-2012, 03:45 AM
P.S. I already understand raw exposure and try to take photos in a similar manner. I either want to respect the top end of the scene's range or use it as a light source.

morgan_moore
12-14-2012, 04:07 AM
Stills wise when I popped the my D3 out of its box in 2008 and saw what I knew I had wanted ever since I gave up film - highlight roll off

It is the film attribute IMO, the holy grail of digital aquisition

You are right, cameras like the Sonies just dont have it

Bascially thats what I hope you get when you go to BMC..

Of course you should not judge cameras (like the sony) by what 90% of people do with them

For example here is one of my many many efforts with the FS100, https://vimeo.com/34622682 watch it throught until you see the pre grade version!

S

nickjbedford
12-14-2012, 04:19 AM
I turned on HTP on my 5D III today when shooting some landscapes. Yet to load them into Lightroom to see how it went. Usually I get pretty good exposures without it, but I'm curious to see how it changed the metering.

morgan_moore
12-14-2012, 04:46 AM
Are you talking in general - or specific to your canon?

IMO the 5d (2) is pretty good in this department (for H264 muzzo vision) which is one reason it became such a legend

As for the HTP mode - Ive never used it but it does not have very good press..

S

John Brawley
12-14-2012, 06:30 AM
I turned on HTP on my 5D III today when shooting some landscapes. Yet to load them into Lightroom to see how it went. Usually I get pretty good exposures without it, but I'm curious to see how it changed the metering.

It works differently in video compared to stills.

jb

nickjbedford
12-14-2012, 06:36 AM
Yeah I wasn't using it for video today. In video you have a histogram, so it's not really relevant. In stills, you don't have a raw histogram so you can't expose like the Blackmagic. In stills, you're metering on 18% gray (I assume) then adjusting accordingly, not metering for sensor clipping. I'm not entirely sure if anything changed. The minimum ISO increases to 200 in 5D HTP mode. I should read into it. But that's another matter.

Joe Giambrone
12-14-2012, 07:11 PM
"For example here is one of my many many efforts with the FS100, https://vimeo.com/34622682 "


Still overexposed to me. Anything with direct sun need massive stopping down and ND. I shot a short on a Vixia, and it was at -3 stops to get the highlights barely near where I wanted them. Even some of those looked over on hot edges of faces. DR is everything.

CaptainHook
12-14-2012, 07:14 PM
I don't think HTP really does anything in RAW (stills mode in 5Ds) you can't do yourself..

Here's some excerpts that i believe to be true as to how it functions (but honestly i haven't tested myself):


When you enable HTP in the camera, the camera meters and exposes for the selected ISO. But the guts of the camera actually shoot at one full "stop" lower ISO setting than what you (and the camera's metering) thinks it's using.

So if you shoot at ISO 200 (HTP enabled), the camera actually sets its internal amplifiers to the proper gain for ISO 100.

Hence the minimum being iso 200


OK, so what does this mean for RAW shooters?

If you use Canon's DPP or RIT to process your images, a special tone curve is applied that gives the desired effect.

If you use a non-Canon RAW converter on HTP shots, we cannot predict exactly what will happen for various converters. They're all free to do what they will.

For ACR, testing has shown that Adobe recognizes the HTP "flag" in the file's metadata and simply turns up the "brightness adjustment" by one stop across the board. So the HTP shots are brightened to account for their one-stop underexposure but you end up with nothing having been done to preserve highlights.

Instead, you've just got more noise with no highlight protection by default. So by itself, an HTP shot converted in ACR is of no benefit.

BUT (and this applies to JUST what you said you do), if you shoot with HTP enabled, and then pull the highlights back in ACR using the highlight recovery tool, you probably end up with something very similar to what the camera, DPP, and RIT would have done.

In effect, by using the highlight recovery slider, you are doing the final missing step in the "proper" HTP "formula". It's not as convenient, perhaps, but the end result may well be every bit as good - and it's adjustable.

So as long as you're aware that ACR is doing part of the HTP correction but that you need to "finish the job" when working with HTP files in ACR, then you can get some benefit.

On its own, ACR doesn't get it right. But if you do your own curves adjustment, or use the highlight recovery tool, you can approximate what Canon had in mind, I think.

From here:

http://forums.dpreview.com/forums/post/26992447

Granted its old so things may have changed (say with how ACR handles HTP now - i use Capture One rather than Lightroom), but that's what i read back then and haven't had reason to think otherwise since.

nickjbedford
12-14-2012, 07:17 PM
I wonder if there's a correlation between this highlights priority aesthetic and the way we see?

I've noticed that it's very, very rare for our eyes to see what you might call "blown highlights" (hot white areas). Only very bright areas that are likely light sources.

Yet our eyes will happily allow shadows to become a wash of dark grey which we cannot discern any information.

For example, if you've ever driven on a bright sunny day then into a tunnel, then as you are coming out, with the bright daylight shining down the opening, you can barely see any information in the dash whilst your eyes are exposing for the highlights. I suppose this also has the important effect of not burning your retina ;)

nickjbedford
12-14-2012, 07:20 PM
I don't think HTP really does anything in RAW (stills mode in 5Ds) you can't do yourself..

Here's some excerpts that i believe to be true as to how it functions (but honestly i haven't tested myself):



Hence the minimum being iso 200



From here:

http://forums.dpreview.com/forums/post/26992447

Granted its old so things may have changed (say with how ACR handles HTP now - i use Capture One rather than Lightroom), but that's what i read back then and haven't had reason to think otherwise since.

Yeah I use the highlight recovery slider a lot when I'm dealing with high DR raw stills. To be honest, raw is raw and a sensor is limited to a certain dynamic range and I've always had a LOT of room with the raw files anyway.

CaptainHook
12-14-2012, 07:29 PM
Yep, although the few times i have used ACR in Lightroom i felt the highlight recovery did odd things to skin so ever since i tend to D&B in the raw convertor on layers instead. Takes a bit longer but i don't have to worry about skin. Of course there are times where it's not an option (or even more rare that i'm not shooting people) so i will use highlight recovery in C1. :)