Understanding Contrast Ratio
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- Опубліковано 23 бер 2023
- Contrast can be talked about in many ways, but contrast ratio comes from a photographic understanding of contrast, meaning it's how the people who are shooting the footage are thinking about contrast as they're creating a shot on set. This video will cover what contrast ratio is, and how you can use it to guide your color grading.
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Beautifully explained! Professional, straight to the point and important to mention an approach that respects the job done in the set. Great Cullen!
the contrast perfectly harmonizes with the overall picture and a soft image is obtained with accentuated shadows. This is an insanely important technique in color correction. Thanks Kelly
Love this lesson and how it is explained Cullen. Also really identify with your "less complex" philosophy in overall grading. This lesson will change the way I set up grades. Thank you for all you do. Always looking forward to the next one :) 🤘😃🤘
Thanks for your work, Cullen 👍👍👍
What a freaking legend. Thanks!
never thought other way around, thank you for this, moving contrast right introduce sat, so if we need same contrast/expo with sat do it other way around. which will give me same look but no sat. this is what I understood. please correct me if I am wrong. and thank you for this great video
Thank you for all of your awesome insights, such a huge help in learning how to more accurately and properly edit/color footage 🙌🏻🫶🏻 Keep it up
Thank you Cullen!
Just great as always, thanks so much! There is an interesting question from RedCat and i wonder what you'll respond, Cullen.
I think it's good to reference this back to photography. I would take that step further though, as photographers refer to specific ratios as in the number of stops difference between key and fill. As in 2:1, 3:1, 4:1, 8:1, and associating specific styles these numbers. That makes it less subjective (moderate contrast means different things to different people). Although colorists don't usually have light meters around or know what the light was set, I think adopting that thinking and language can help in communicating with DPs.
Good point.
@@CullenKelly That makes sense. Other tools do provide that information, but may not be accessible to everyone here. Nuke for example has a standard mode of it's color picker where it reads out the color in RGB and L in linear values, and also computers the f stop at the projects frame rate (exposure) and preset ISO. So you can literally get this information from the standard color picker.
For the broader audience, maybe just showing a Photoshop mock-up of the contrast at 2:1 vs. 4:1 maybe a helpful visual calibration, even if you can't get a read-out of your actual image. More like a guide-tool to help set your eye with.
Check out the EL Zone System, it’s a false color based exposure system by Ed Lachman that uses stops - tuned to specific camera log formats and isos.
@@Vautksch Good point. I always have false color open in Omniscope while grading. I find it helpful for judging some of these aspects. There's a fine line between trusting your eye and using a calibrated system. But on long days grading, your eyes can get tired or play tricks on you. So doing a combination keeps you grounded.
Thank you so much!
Thanks Cullen
Would like to see your color space/gamut transformation from the brand new GoPro Wide Gamut (GWG) to DWD with a raised log base like 250.
You are really wonderful
Thanks Cullen! As a long time still photographer, your adjustments make perfect sense and are familiar. But how do these adjustments manifest on the entire clip? That's part of movie editing that I find difficult. These aren't static images but the adjustment is....?
Thank u so much sir♥
Although the lesson is about contrast ratio, there's a reason that people should watch video in context and analyse the image in context. The results given are beautiful, but the exposure and the contrast pivot on the subject has to be determined by the motivating light and be part of the selling of the scene.
So the girl outside who has less contrast ( even though you said the scene had little contrast ) the reason given was that she was outside lit by the sun. We as humans can actually tell the difference and if she was lit with a key light outside - it wouldn't look natural to people and they would sense something was not right.
And the lady that looks to be in bed. If the clip before was someone quickly opening up the curtains, after a night of drinking etc., and the sun was rushing into the room, then the "high key" of the contrast might be the best choice.Softening it, reducing it, or making it look like the light is coming from a lamp on a side table, would be telling a different story. Honestly, the lesson with this should be that the contrast needs to help tell the story and how a colorist, if not thinking context could easily change the story.
The lighting ratio on a person's face is always considered from the direction of the light. There can be an intense light, but if it is more behind in direction, and a person turns their head away, the dark side of the face will be darker. And the more the head turns, the lighting ratio line ,will go from soft as it has more light to hard when the angle changes.
And with the information in this video, it seems to me that people will be confused as to the ratio when you talk about key lights and then switch the wording to scene. The scene can have too much contrast and the face can be in the scene and be the opposite.
So it is my opinion, that all contrast on the subject has to be in context and in most productions, if edited correctly will be decided by the clips before and sometimes after to assess where the contrast or key to fill ratio should be on the skin.
Sorry Cullen for the long winded response.
maybe we should have a grade school about analyzing footage
Thanks for the video! Very interesting and helpful as always.
Q: you always say that one of the principles you follow is to preserve middle gray. But as I understand the core concert of contrast/pivot tool - the pivot at self is kinda middle gray setting (because technically it's the anchor point of our curve, the point which shouldn't move to prevent moving the exposure up and down).
And while you move the pivot point just by eye, don't you break your own rule? I totally get that for you it could be like an automatic action, a muscle memory, but for those who don't have a ton of experience just yet, wouldn't it be better to set the pivot point according to the middle gray of your working color/gamma space?
Hey Cullen😄
Can you please shed some light on how to set up a "Custom Color Processing Mode" when working in "DaVinci YRGB Color Managed" Going a little in depth on topics like "Timeline Working Luminance" "Limiting Output Gamut" & "Input/Output DRT"
Should we discuss shot *length* as a function of contrast? I feel like you can 'get away' with much higher contrast for a quick reaction shot vs. a longer shot, or sequence. High contrast, over time, I feel like becomes fatiguing for the viewer (like too much salt over the course of a meal). Conversely, if you're wolfing down a couple of hot dogs between classes, meetings, appointments, etc., then you kind of want it 'all at once'. Would love to hear any thoughts.
How do you manage PNGs JPEGs and Overlays in a DWG Workflow so that the Images dont get wrong transformation and look different?
I usually start with Offset and then use Lift, Gamma and Gain. It’s interesting that you didn’t even touch them.
How do you measure contrast ratio in resolve in stops? Do you need a false color lut?
Can anyone please explain how Cullen uses color space Lab to preserve the colors and only affect the contrast ratio in a node. I know that Cullen has brought it up in some videos but I cant find which ones. /Sebastian
Hi Cullen, this question is pretty much completely unrelated to the video, but I'm struggling with color managing the footage from my Canon EOS R7. I've set up my CM to Canon Cinema Gamut / Clog-3 -> Rec709. However, the way my controls work doesn't seem to be the same as yours. I've tried using Davinci Wide Gamut Intermediate aswell, but that seems to make the image way to contrasty.
Any input on what I might be doing wrong?
great
Using the offset to set the key side is such a simple tool but a great direction to start.
Question: when I start to add contrast using contrast/pivot, the skin starts to look over saturated with orange. I like the tone, but not the color. Any ways to combat this?
Thank you for all the amazing content!
Maybe take some sat away, because when you add contrast you're also introducing saturation
@@Crimbtw would that be an overall adjustment to the saturation, or just specific elements?
@@flochfitness I'll say overall, but I think it may also depend on the footage, what you or the client wants etc
You could adjust contrast on a layer mixer node set to luminosity to not affect saturation but honestly it's easier most of the time to just dial out a small amount of saturation in a new serial node.
I come from a background in stills retouching and the way I've always worked with global adjustments like these is to keep exposure, contrast and saturation separate.
You can use contrast knob in HDR panel. It affects luminosity only
Hi I work in Unreal Engine. I wanted to make a short film inside of Unreal in which I create the look of Split Second starring Rutger Hauer in 1992. It's an old Cyberpunk film, and thus far the only advice I've been getting is to just put a VHS filter on it. But that's not what the movie looks like, that's what it looks like on a broken VHS tape. Any chance you could point me in the right direction? I want to create a look that is indistinguishable from those old movies.
❤❤❤❤❤
How do you add a look to timeline level without it affecting text?
I don’t believe you can. Timeline grading will always affect everything within that timeline. I’ve never been bothered by it, since I believe that the overall grade impacts the text in an appropriate way (i.e. if there are no true whites in your grade, you may not want true white in your text).
If you want to avoid it, you can try a shared node at the end of each clip (minus your text clips) that acts like a timeline grade. Or, you can add all of you clips into a group, and do a post-group grade.
It is Saturday, I now we love color grading, but I wouldn’t be mad if we wait until monday 😂 now I have to watch this
When does round 3 of colorist career start?
This Sunday
Do you always grade in a room filled with tungsten lights? 😵💫
@@CullenKelly I think it has something to do with how you will perceive the footage.
@@CullenKelly Display gamma at 2.2
@@CullenKelly Cullen really said, " never let them know your next move."
@@CullenKelly so basically you dont, but you said you did. cuz, humor?
@@CullenKelly okay I get it. But when you make these videos, you are color grading, and the lights are all on.
Hello Cullen. In some past videos you recommended to use Linear Gain instead of Offset. Do you use that for Exposure or Ratio? Thanks so much for this video
Exposure. You can try and experiment contrast ratio in lin gain and see what it does
Is Cullen Kelly ASC certified? I think thats for cinematographers but there must be group for the colorist guild