Question about color grading.

[harmonica44]

A lot of people say it's best to white balance the light on location, to white. Then you have more freedom to color grad in post, since the light is white. I want light at night to be orange sodium looking for a project for example. But my DP says shoot the light white, then color grade in post, so you have more freedoms.

Here's a shot I took of the orange lamps, balanced to white while shooting. I then added orange in post. But if I do that, the sky comes out purple. Where as if I white balance to orange on set, it does not. So is making the light white, on set, really a good idea therefore? Another thing I've noticed is that color grading in post seems to have more noise than white balancing on location. Or am I just color grading wrong probably?

http://youtu.be/MR3m5KiTxeE

 

[escher]

Unless you've got the time to sink into massive color grading, I'd recommend getting as close to your final look as you can in-camera, shooting with a flat profile if you're using a DSLR.

Also DSLR-specific: due to compression issues, you risk making compression artifacts very visible if your final look is extremely different from what you shot. If you've got a real HD video camera (eg. not shooting straight to h.264), this is much less of an issue.

 

[harmonica44]

Oh well I will probably be shooting with a DSLR at h.264 for the project.

 

[jax_rox]

Get the look you want in camera.

Shooting flat doesn't really help, especially if you don't understand colour grading. but some swear by it. I personally don't white balance to a white card or the like - I dial in Kelvin temperatures, and generally stick to 3200 or 5600.

It's obvious you don't really understand colour grading, which is fine - but it doesn't make sense to 'shoot for grading' (which I personally hate anyway) when you don't know how to grade.

What you've posted could certainly be graded so the lights go orange, but the sky and the rest of it doesn't go purple, but considering you can get the look you want on set, it doesn't make sense to not, and by pushign the grade too much with an 8-bit compressed image, you start to bring in extra noise and artifacts that you really don't want.

 

[Sweetie]

Either can work. The safest is to color balance to white during shooting assuming you have access to color grading.

When I originally learnt all this, cheap color grading wasn't available. You had to learn to do it all in camera and the problems came up when the footage didn't match. You can do it your way. You might even need to color grade it anyway. Anyway, what would happen if you graded it in camera slightly towards red and in post, you worked out that sifting it towards blue was your better option?

You use Adobe, have you tried speed grade? Try running your footage through Speed Grade before you begin editing.

Whatever decision you choose, test the process/workflow to see if it'll work for you. Try different workflows and wee what problems come up. That way, you don't get to post with a problem you didn't anticipate where your best option is to reshoot.

 

[knightly]

I prefer getting it in camera, but those sodium lights suck all of the color out of the blue color channel and push it all into red (mostly) and a bit of green. It's impossible to pull back away from it if you change your mind... but it's also very difficult to emulate in post. I'd recommend you shoot it in camera the way you want it to look... expose correctly for the lights you're using and make it a decision that you're making on set... then just go with it. True, fewer options in the grade, but it sounds like you already know what you want from it... so why not get it in camera? It'll save a ton of time in post not having to come up with a way to get back to what you got rid of on set.

 

[harmonica44]

I did some more tests and I just noticed that different white balances of different levels of noise. If I balance to the sodium lamps outside, they turn white but there is a lot more noise, compared to if I shoot under a white fluorescent balance. And although white flourescent makes the sodiums orange, it has more noise compared to a tungsten balance. So perhaps in order to achieve the best picture quality, I should choose the white balance with the least amount of noise? This is while at 6400 ISO though. When it comes to shooting a real project I would use a 1.4. lens. This is for wide establishing shots of streets and buildings where I won't be using lights as well. I noticed that different white balances produce different levels of exposure and shadow patterns as well...

 

[MileCreations]

I did some more tests and I just noticed that different white balances of different levels of noise. If I balance to the sodium lamps outside, they turn white but there is a lot more noise, compared to if I shoot under a white fluorescent balance. And white flourescent, although it makes the sodiums orange, has more noise compared to a tungsten balance. So perhaps in order to achieve the best picture quality, I should choose the white balance with the least amount of noise? This is while at 6400 ISO though. When it comes to shooting a real project I would use a 1.4. lens. This is for wide establishing shots of streets and buildings where I won't be using lights as well. I noticed that different white balances produce different levels of exposure and shadow patterns as well...

I've always been taught to never put the ISO above about 800, or the shutter speed above about twice the frame rate

 

[jax_rox]

ISO 6400 is going to produce a ridiculous amount of noise. Even at 800, I can visibly see noise in underlit scenes.

You're better off lighting, btu I've said that in the past.

 

[harmonica44]

yeah but these are for shots of skylines and the city. Not lit scenes. I don't have a 1.4 lens. Just practicing so I know what look I want for when I want to shoot. Then the DP will whip out his 1.4 for shots of the skyline, where we cannot light every building in it. We will shoot at 800, 1/50, and whatever f stop is required when we get there on that day.

 

[jax_rox]

Well then your point about noise becomes null and void; of course there is going to be more noise at a higher ISO

 

[harmonica44]

But what I mean is, if one white balance has more noise than another at 6400, wouldn't that same balance have more than the other, at 800 as well?

 

[knightly]

But what I mean is, if one white balance has more noise than another at 6400, wouldn't that same balance have more than the other, at 800 as well?

Most likely that would be technically true, but it wouldn't be as noticeable as when you're turning your amp up to 11. It's distortion... and cranking your ISO up is exactly what you want if you're playing heavy metal with light... but not so much if you're trying to get a clean, classical image.

 

[harmonica44]

Okay thanks. Well I've been trying different ones on orange and it's difficult to tell what looks the best. Some white balances look good in some locations, terrible in others, and vice versa, with other balances. I think the exposure has something to do with it too, as tungsten looks better at lower f stops, rather than a bit higher for example. It goes from gold to gold/green. And white flourescent goes from a nice orange red, to peach, depending on the exposure. So I guess I will have to determine which white balance should be used, based on the exposure of the scene. If that's a good way to do it.

 

[ItDonnedOnMe]

I did some more tests and I just noticed that different white balances of different levels of noise. If I balance to the sodium lamps outside, they turn white but there is a lot more noise,

I prefer getting it in camera, but those sodium lights suck all of the color out of the blue color channel and push it all into red (mostly) and a bit of green.

These two things are related - I personally generally prefer doing a custom white balance in camera for any given lighting setup, but there are unusual situations like this where that probably doesn't make sense.

White balance works by adjusting the gain on each channel (red/green/blue) independently in order to balance out the dominant color of the lights. If you shoot under lights that provide almost no light in a wavelength that corresponds to one of those channels (i.e. sodium lights, which don't really have a blue component) then to balance it the gain on that channel has to be increased significantly compared to the other two. So you may be shooting at an overall ISO of 800, but your blue channel could be running at the equivalent of 6400 or worse. More gain = more noise.

To make it worse in this particular situation the blue channel tends to be the least sensitive in digital cameras, so it's already generally noisier than the other channels. Now you're pushing that even further, and then encoding it to a 4:2:0 colorspace where the blue channel ends up at 1/4 the full resolution, which tends to make the noise look 'blocky'. It's a recipe for disaster. So basically, if you're shooting for the yellow look of sodium vapor lights, shoot with them and balance in camera to get close to the final look. If you're trying to get a balanced white look to your lighting then don't shoot under sodium vapor lights.

This also goes to the argument for preferring daylight balanced lights for any sort of digital imaging, whether you are shooting indoors or out. Daylight balanced lights have a strong blue component, so when you white balance to them you are lowering the gain on the noisiest channel - blue - resulting in less visible noise at any given ISO setting compared to using and balancing to tungsten light.

 

[knightly]

Alot of what you're experiencing is this:

from: http://assbook.blogspot.es/i2012-09/

Color in light works by a material (wall, plant, pigment, person) absorbing all of the colors of the source light, but reflecting the specific frequencies that represent the color you see them as.

In the right side of the image, white light hits the grass, the green component of the light is reflected to the camera and recorded in the green channel by the camera. Some blues and reds in much smaller amounts are also reflected and recorded by the camera, but primarily green, when combined later, they show that particular pixel as green with just a touch of red and blue.

In the left side of the image, there's so little non-orange components to the light, that there's not much to reflect back... so the grass only has red to reflect back and the camera to record. Since the data doesn't exist in the first place, it's REALLY difficult to get it to com back simply using white balance... doing so (in camera or after the fact!!!) will artificially amp up the greens and blues (overdriving them far past 11), and pull down the reds (which is fine). So you end up with noisy blue and green channels as you're pulling something from nothing... as if you had set your RGB channel's ISOs separately, Red at 100, Green and Blue at 6400... the reds will look fantastic, the green and blue will look like shit and there's no amount of digital trickery you can do to repair it (in camera or in post!!!). GIGO (Garbage in, Garbage out).

If you want it to be orange, record it orange, make it look good in camera. If you're going to push it orange, record it white (by adding your own lighting and turning off the street lights), then put on an orange overlay in post to all or part of the image.

 

[jax_rox]

In relation to Knightly's point - it's this exact reason that using CTB gel on a tungsten fixture cuts so much of the light - when you put a CTB gel on you are essentially 'cutting' as much of the orange spectrum as you can, but because there's so little blue in such fixtures, you lose 70% of it's output.

 

[harmonica44]

Okay thanks people, that helps a lot. I have been doing more tests and it seems the best white balance to get to that orange as in the same picture, is to set it to cool white fluorescent. At least that's the best I have come up with so far. Will do more tests...