All language subtitles for 13_Film_grain_and_digital_noise

in this lesson

we're gonna learn about film grain and digital noise

so as we've made our travels through the camera

we've gotten through the lens

we've gotten through the aperture

and we are finally hitting the sensor

now here you might expect that everything is good to go

however there are some problems that arise

in the sensor or on our film

namely film grain and digital noise

so let's take a look at a

few examples of this before we add it into our comp

so this is a very um

extreme version of film grain

and we can see here that are areas

even areas that are in focus have this strange pattern

and this pattern is in our different color channels

and this if the picture was moving

would actually be changing every single frame

now on the other side of the world

um excuse me

in digital we have something called digital noise

and this happens

uh very similar to film grains

so let's take a look at that oops

so here is a picture without any noise

and here is a picture shot at a much higher ISO

if you recall our second lesson

we talked about the ISO and the sensitivity

as being aspects of film and digital sensors

which controls how much light they pick up

and how much light they amplify

so let's take a look at why

a film grain happens

now this is actually a picture of film crystal

silver highlight crystals on a piece of film

and you'll notice that there are many different shapes

and many different sizes

now this is because we want our grains of film

to be different and to be sort of random

so what we get is we get this sort of random

um collection of shapes and sizes

and they combine to create film grain

so we can see in this image

we have random sizes of this film grain

some of it is very small and some of it is very large

now you might ask

why don't they just have a single size

and the reason for this is

larger crystals are more sensitive to light

but you need smaller crystals so that you

can have fine details

so they have to make a very measured

uh sort of mixture whenever you create film

now this picture you see here is one layer

uh you can have or you have a unique

layer of crystals in the red

green and blue channels

so what that means is film green changes

whether it's in the red

green or blue channels

so if you want more sensitive film

or if you wanna shoot in a darker environment

you need to have larger grain sizes or a larger

ISO speed film

however that leads to more grain and more

visually noticeable grain

so you always have to be careful

uh to get the shot you want

but with the least amount of grain

now on the digital side

you might be thinking well

all the digital sensors are the same

why would we have this problem here

and the problem is not a a

a problem of size

it is a problem of intensity

so what the sensor is doing whenever it is

increasing its ISO or increasing its sensitivity

is to increase the

amount of energy it is pushing or the

or decrease the amount of energy it needs to

light up a cell

so what happens is the noise

just the general noise

uh from different lights

from electrical noise

from heat uh

begin to create these digital noise effects

and as humans

digital noise is

not as nice as film grain

film grain has a

uh very positive quality

it is random

it is randomly distributed

it has random shapes

and those are all aspects of grain that we like however

with digital noise

our our sensors are based off of uh

what's called a Bayer pattern or a Bayer filter

which essentially looks like this

so you can see here of course

our pixels are arranged in a very orderly fashion

what this creates is very orderly digital noise

and our eyes

and our brains can pick up on that repeating pattern

and we really don't like it

especially if it's moving around in our frame

a digital noise is

uh almost always to be avoided

unless of course

you're going for a cheap

camera shot

and then you can add in digital noise

however in our case

we're gonna want to remove as much noise as possible

and then add in grain

so let's jump over to nuke

this is gonna be a relatively simple operation after

all the work we've done

and let's just drop in a grain node

and this comes with many

useful presets for creating grain inside of our image

now if we take a look at this node

uh separate from everything else

we can see that

if we turn off

apply only through alpha

well I guess we don't have any black grain

and I don't wanna add any just yet

so let's plug this back in

we'll notice that the grain

changes every single frame

if we jump forward

and jump back

one or two frames

give us a second to load up

so we can see the grain is changing size

shape and position

every single frame

and that is of course

because a piece of film

or a roll of film

every single grain is

unique to that

explicit frame

so it's gonna change every single frame

so one thing we need to do

before calling this good to go

is we need to match

the size of our grain

because currently

the grain note is set to a 2K image

if you have a weird question Mark

you can see here

these are the correct

sizes for 2K scans

now we are not using a 2K image

so we're gonna have to do a little math

I'm sorry to

fix the grain node

so let's go to our size here

and we have our full size format

I'm just gonna create this

and fix the pixel aspect ratio

so this is gonna be our 7 20 p size

so we have 1280 by 7 20

and so now let's go into our

let's first write down what the values are

for a 2 k plate

we can find this in our project settings

full size format

and it's the 2 k

uh Super Cinema or excuse me super 35 millimeter

so 2,048 by 1556 okay

so let me just bring up a quick notepad here

so our full size are 2K format is a

2,048 by 1 5

5 6 and our current format

is 1280 by 7 20

so what we need to do is we need to calculate

how much smaller the grain should be

so it is the same size

in our smaller frame

and of course

depending on what size frame you're using

what size footage you're working with

uh you'll need to put your own numbers here

and then do the calculations

so if I bring up a handy dandy calculator

and I plug the numbers in

let's plug in our current frame size 1280

and then let's divide this by

the target frame size of a 2K

so for the x axis

we get point six two five

and for the y axis

we get 7 20 / 5

5 6.462 okay

now I'm just gonna use point six two five

I'm not going to change the aspect ratio of the grain

now that's gonna

make things look very strange

so to do this

let's go into our grain

and this is controlled in the size

so let's do 3.3 times

our point six two five

hit enter and nuke

nicely enough

does the math for us so again

multiply by point two

six five multiply by 2.265

excuse me point six

six two five

uh good old dyslexia

and we have the correct grain size

now if we compare this with the original size

it's gonna be

very different

so let's take a look at here

so the original size had very large grain

while with our change

we have much nicer

much smaller grain

now we could of course

use the even smaller value of point four

I believe 6 2 it was

but again uh

I believe this is close enough

so now we have green on our frame

and of course

you can come in play with a different presets

uh going and change your intensity values

maybe this grain is a little bit too strong

uh remember

grain increases

the darker it is

you're trying to shoot

so grain increases in

uh darker shots

now if you're outside with a lot of sun

you're probably not gonna need to use ISO

16 film unless you

have 10 neutral density filters on your camera

which it would be rather strange indeed

so in this case

when we have a very bright scene

we can pull

the grain back a little bit in its intensity

because again

we would be using a faster film stock to shoot outside

and a lower

ISO if we were using the digital

counterpart

now you notice the intensity values are actually

rather interesting

the red is the lowest

next comes the green

and then the blue

is very large

or very intense

and this is a very common thing with film stocks

the blue uh

grain is much

much more intense than the

red or green uh grain

so here we go

we can see this nice

subtle grain

it's gonna add just a little bit of movement

a little bit of

uh what looks like sharpness

even though it's just random noise

it actually will

make our picture look sharper

and be much more pleasing to look at

because again

it makes us feel like we're looking

at a piece of film okay great

so let's just talk briefly about a grain workflow

again in CG

you can just add grain here at the end

uh in the real world or in real footage

you wanna take grain out

you usually wanna take grain out of your backgrounds

if you have multiple real world elements to composite

and then regrain them at the end however

if you are shooting or if

you're working off of a fixed back plate

for example

if this was real world camera footage

we could bring uh

this in here

composite whatever we need on top

and then add grain to these new elements

that match our background grain

and that would

stay truest to the background and not modify it

in case you're any more stricter pipeline okay great

so that brings us to the end of this course on creating

photo realistic camera lens effects

here inside of nuke

uh we started with a rather simple uh image

and by using the power of nuke and no base compositing

as well as learning about a few

uh pieces of light physics

we were able to take again

what was a relatively boring 3D render

and turn it into something nice

or at least something nicer

so the image quality uh

has degraded a little bit

but I think you'll agree that it looks much

much nicer with all of our changes

because we tried to mimic reality wherever we could

and use the rules of nature

the rules of

that control our glass lenses

and the rules of light to add in some of those

subtle irregularities and problems

that we will have when shooting in natural conditions

so as always

I hope you've enjoyed this course

and I can't wait to see how you apply these techniques

to your own project