6 ms·

How is color grading applied if not with LUTs? You know that when you do color grading with apps like Resolve, it is stored in memory as a LUT, right?

by caseyy 2y ago

dylan604 2y ago
> How is color grading applied if not with LUTs? No absolutely not. In Resolve specifically, you have nodes that you apply to the video where each node allows for specific settings to be applied as part of the grade. In a true grading session, you dial in the settings for black levels, white levels, contrast, saturation as primaries. Then there's secondaries which start finessing. You can then draw windows/mattes to isolate a specific area or specific color range (think color image where everything is B&W except the red rose/red car/red dress style) to apply the grading. There's also tracking of those windows. There's so much more going into color grading than "apply LUT here". Just look at the control surfaces for Resolve and the number of knobs/buttons/rollers. Would something that just applied LUTs need all of that? > You know that when you do color grading with apps like Resolve, it is stored in memory as a LUT, right? Source? That's a very gross oversimplification of what a color session is like. LUTs don't do tracking. LUTs don't do keys. LUTs don't do mattes. You are doing colorists a disservice if you think grading is just LUTs.
- lukevp 2y ago
  I also thought grading was just LUTs. Does kino let you do all of the things you mentioned directly in the app?
  - dylan604 2y ago
    Might I ask why this is all you thought a grading session involved? Clearly, this is a touchy subject for me as I spent a few years as an assistant to a very talented colorist. The plethora of YouTube videos saying color correct using my amazing LUTs available when you join my Patreon blah blah nonsense is really sad. There are some truly amazing colorists, and then there are people that claim they are colorists when they just applied a LUT. I would be embarassed to call myself a colorist that way. With my experience, I still do not call myself a colorist. I also don't go around calling myself a DP because I own a camera and make pretty pictures, yet people go around with no real training calling themselves that because it's cool.
    - lomase 2y ago
      You are on a tech forum. People are going to talk about the technologies that make possible color grading. Without LUTs, Look Up Tables, a computer would not be able to do color grading.
- th0ma5 2y ago
  This is all I ever hear though. It isn't (just) LUTs, a bunch of posturing, and then "but it is magic that I can't share or you wouldn't understand."
  - dylan604 2y ago
    Not understanding might not be far from the fact, but it is probably just posturing. I doubt most of the Tubers understand it themselves which is the real reason they can't share. They saw it on some other YT video, and then made it like it was their own idea. I've tried to explain how to use waveforms/vectorscopes and why they are important. Those things are rarely used any more, and people just don't realize how much more difficult they make it on themselves by not using them. Just because you can push that knob to an 11 doesn't mean you should. Pushing that knob while looking at the scopes will tell you when to stop. This was life or death when making content for broadcast. Also, I've seen all sorts of weird things that blindly applying a LUT wouldn't solve. There was a specific Red camera in town that had a very strange issue where the green color channel was not recording correctly. One shoot we had footage on was of an ice cream type place that had lots of whipped cream on the desserts. However, as you pushed the levels up, the green lagged behind so as the red and blue channels were maxing out the color on the screen went magenta. Applying a LUT would have looked terrible, but the colorist was able to go in to adjust the levels of the green channel separately so that the cream went back to white. It saved the shoot because a camera was not working properly. There's also interesting tricks to do like when shooting through windows of a high rise will give a green tint to things. So lowering just the green channel will bring things back which could be a specific LUT, but the thing with LUTs is they tend to get used for the wrong reasons. Shooting underwater without a filter can also be dialed back, but it's specific to camera/depth type of situations. Another common ask was to "open up the eyes". Well lit faces are notoriously hard as the sunken eye sockets just naturally shadow. So you add a window to the eyes and push the exposure up to achieve the effect that no LUT will ever achieve. If the camera moves for a tracking shot, the windows can track along with it. No LUT will ever accomplish that either. The eye is naturally attracted to the brightest area of the screen, so there's ways of grading something so that it suddenly receives some attention that a LUT would not get there, again using windows. Some of the internationalization of releases have small forensic tells in them to indicate which locale it might have been leaked from. One specific example was a stack of towels in the background of various colors. Through color correction, they changed the colors of the towels to be different for each region. So so so many things that well graded footage can have done to it that "you wouldn't understand" but would never come close to achieving with a LUT. Wouldn't understand is very harsh though, and is a total cop out from someone that sounds very pompous. I would say "wouldn't consider" as something that could be done let alone needed to be done.
- caseyy 2y ago
  You seem to misunderstand the role of LUTs in color grading. LUTs (Look-Up Tables — a simple multi-dimensional array data structure) describe how one color is transformed into another, and they are used for efficient color transformations. In Resolve, the tools you described help build a LUT in memory, which is then applied to each pixel in each frame, often using SIMD instructions for efficiency. This avoids the need to procedurally apply each setting to each pixel individually, which is way slow. Drawing windows, mattes, tracking, and other masking tools determine where and how the LUT is applied within the rendering pipeline. > Source? That's a very gross oversimplification of what a color session is like. LUTs don't do tracking. LUTs don't do keys. LUTs don't do mattes. I work in AAA games and have written code for tonemapping and color grading. We often use a gbuffer (graphics buffer that could be seen as a 2D screen-shaped image that is never shown) to mask different objects in the scene and apply different LUTs accordingly. So, it is not only LUTs that are applied in a similar screen-space way, but also masking is similar. > There's so much more going into color grading than "apply LUT here". Just look at the control surfaces for Resolve and the number of knobs/buttons/rollers. Would something that just applied LUTs need all of that? On a low level, it essentially is about applying LUTs. How you create these LUTs and how you mask their application are crucial aspects of the process. But ultimately, a LUT is applied to pixels. You are talking about the artistry techniques involved in making a LUT and masking where it is applied, which is not debated. LUTs are not just files you can import and export to grade the whole image or frame. They are a fundamental compact data structure that makes SIMD operations easy, which is why they are used in grading. If you set up a color grading pipeline with nodes in Resolve, it is very likely compiled into one or more LUTs, which are then applied to the frames.
  - dylan604 2y ago
    My contention isn't how a LUT works in the background technically, but the fact that people consider applying a LUT all of what a colorist does. If you want to simplify it to that level, then it's really not even a conversation worth having as that's not the answer to the question.
    - caseyy 2y ago
      > If you want to simplify it to that level, then it's really not even a conversation worth having Hehe, you are not wrong.

How is color grading applied if not with LUTs? You know that when you do color grading with apps like Resolve, it is stored in memory as a LUT, right?

by caseyy 2y ago

How is color grading applied if not with LUTs? You know that when you do color grading with apps like Resolve, it is stored in memory as a LUT, right?

dylan604 2y ago

> How is color grading applied if not with LUTs? No absolutely not. In Resolve specifically, you have nodes that you apply to the video where each node allows for specific settings to be applied as part of the grade. In a true grading session, you dial in the settings for black levels, white levels, contrast, saturation as primaries. Then there's secondaries which start finessing. You can then draw windows/mattes to isolate a specific area or specific color range (think color image where everything is B&W except the red rose/red car/red dress style) to apply the grading. There's also tracking of those windows. There's so much more going into color grading than "apply LUT here". Just look at the control surfaces for Resolve and the number of knobs/buttons/rollers. Would something that just applied LUTs need all of that? > You know that when you do color grading with apps like Resolve, it is stored in memory as a LUT, right? Source? That's a very gross oversimplification of what a color session is like. LUTs don't do tracking. LUTs don't do keys. LUTs don't do mattes. You are doing colorists a disservice if you think grading is just LUTs.

lukevp 2y ago
I also thought grading was just LUTs. Does kino let you do all of the things you mentioned directly in the app?
- dylan604 2y ago
  Might I ask why this is all you thought a grading session involved? Clearly, this is a touchy subject for me as I spent a few years as an assistant to a very talented colorist. The plethora of YouTube videos saying color correct using my amazing LUTs available when you join my Patreon blah blah nonsense is really sad. There are some truly amazing colorists, and then there are people that claim they are colorists when they just applied a LUT. I would be embarassed to call myself a colorist that way. With my experience, I still do not call myself a colorist. I also don't go around calling myself a DP because I own a camera and make pretty pictures, yet people go around with no real training calling themselves that because it's cool.
  - lomase 2y ago
    You are on a tech forum. People are going to talk about the technologies that make possible color grading. Without LUTs, Look Up Tables, a computer would not be able to do color grading.
th0ma5 2y ago
This is all I ever hear though. It isn't (just) LUTs, a bunch of posturing, and then "but it is magic that I can't share or you wouldn't understand."
- dylan604 2y ago
  Not understanding might not be far from the fact, but it is probably just posturing. I doubt most of the Tubers understand it themselves which is the real reason they can't share. They saw it on some other YT video, and then made it like it was their own idea. I've tried to explain how to use waveforms/vectorscopes and why they are important. Those things are rarely used any more, and people just don't realize how much more difficult they make it on themselves by not using them. Just because you can push that knob to an 11 doesn't mean you should. Pushing that knob while looking at the scopes will tell you when to stop. This was life or death when making content for broadcast. Also, I've seen all sorts of weird things that blindly applying a LUT wouldn't solve. There was a specific Red camera in town that had a very strange issue where the green color channel was not recording correctly. One shoot we had footage on was of an ice cream type place that had lots of whipped cream on the desserts. However, as you pushed the levels up, the green lagged behind so as the red and blue channels were maxing out the color on the screen went magenta. Applying a LUT would have looked terrible, but the colorist was able to go in to adjust the levels of the green channel separately so that the cream went back to white. It saved the shoot because a camera was not working properly. There's also interesting tricks to do like when shooting through windows of a high rise will give a green tint to things. So lowering just the green channel will bring things back which could be a specific LUT, but the thing with LUTs is they tend to get used for the wrong reasons. Shooting underwater without a filter can also be dialed back, but it's specific to camera/depth type of situations. Another common ask was to "open up the eyes". Well lit faces are notoriously hard as the sunken eye sockets just naturally shadow. So you add a window to the eyes and push the exposure up to achieve the effect that no LUT will ever achieve. If the camera moves for a tracking shot, the windows can track along with it. No LUT will ever accomplish that either. The eye is naturally attracted to the brightest area of the screen, so there's ways of grading something so that it suddenly receives some attention that a LUT would not get there, again using windows. Some of the internationalization of releases have small forensic tells in them to indicate which locale it might have been leaked from. One specific example was a stack of towels in the background of various colors. Through color correction, they changed the colors of the towels to be different for each region. So so so many things that well graded footage can have done to it that "you wouldn't understand" but would never come close to achieving with a LUT. Wouldn't understand is very harsh though, and is a total cop out from someone that sounds very pompous. I would say "wouldn't consider" as something that could be done let alone needed to be done.
caseyy 2y ago
You seem to misunderstand the role of LUTs in color grading. LUTs (Look-Up Tables — a simple multi-dimensional array data structure) describe how one color is transformed into another, and they are used for efficient color transformations. In Resolve, the tools you described help build a LUT in memory, which is then applied to each pixel in each frame, often using SIMD instructions for efficiency. This avoids the need to procedurally apply each setting to each pixel individually, which is way slow. Drawing windows, mattes, tracking, and other masking tools determine where and how the LUT is applied within the rendering pipeline. > Source? That's a very gross oversimplification of what a color session is like. LUTs don't do tracking. LUTs don't do keys. LUTs don't do mattes. I work in AAA games and have written code for tonemapping and color grading. We often use a gbuffer (graphics buffer that could be seen as a 2D screen-shaped image that is never shown) to mask different objects in the scene and apply different LUTs accordingly. So, it is not only LUTs that are applied in a similar screen-space way, but also masking is similar. > There's so much more going into color grading than "apply LUT here". Just look at the control surfaces for Resolve and the number of knobs/buttons/rollers. Would something that just applied LUTs need all of that? On a low level, it essentially is about applying LUTs. How you create these LUTs and how you mask their application are crucial aspects of the process. But ultimately, a LUT is applied to pixels. You are talking about the artistry techniques involved in making a LUT and masking where it is applied, which is not debated. LUTs are not just files you can import and export to grade the whole image or frame. They are a fundamental compact data structure that makes SIMD operations easy, which is why they are used in grading. If you set up a color grading pipeline with nodes in Resolve, it is very likely compiled into one or more LUTs, which are then applied to the frames.
- dylan604 2y ago
  My contention isn't how a LUT works in the background technically, but the fact that people consider applying a LUT all of what a colorist does. If you want to simplify it to that level, then it's really not even a conversation worth having as that's not the answer to the question.
  - caseyy 2y ago
    > If you want to simplify it to that level, then it's really not even a conversation worth having Hehe, you are not wrong.