Can someone explain the whole LUT thing?

[Norman Black]

That question is non specific about what the LUT is being used for.

I’ll assume you are talking about the color LUT that exist inside of video cards. The LUT in video cards translates an input color to an output color. In a null table a value if 128 coming in, is output as 128. Unchanged.

Calibration software modifies the video card LUT table when you calibrate your monitor.

[Ron Whitaker]

What I meant was how/when/why to use a Look Up Table during post production editing/color grading.

[Graham Bernard]

[Ron Whitaker] “What I meant was how/when/why to use a Look Up Table during post production editing/colour grading.”

Get beyond the maths in this nVidia entree into LUTs, and see and read the examples.

My interpretation is that one USES a LUT to make the transfer of complex “scenes” colours available for colour correction/grading FASTER by this use of a table set out in a columnar way. It’s efficient and fast. A bit like a relational database report being presented for further usage.

Grazie

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[Thayalan Paramasawam]

(Graham Bernard)Get beyond the maths in this nVidia entree into LUTs, and see and read the examples.

Thanks for the link…….its help me too

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[Scott Simpson]

I came across LUTs when I tried using Technicolor CineStyle on my Canon DSLR. Cinestyle is a picture mode for the Canons that is designed to capture maximum dynamic range and detail at shooting time, so you can have the most flexibility in color grading later.

It was very popular, and might still be…it’s been a while since I looked it up.

On some editing systems other than Sony Vegas, Cinestyle users would apply a LUT – a look-up-table, that would remap the pixel values in the captured file to a wider dynamic range in the editing software. It would take the ugly-looking in-camera file and re-beautify it. Following along so far?

In other words, using the Cinestyle preset and just playing the file back normally, you’d think you captured something ugly and flat. But applying the LUT in editing, all the richness comes back.

What I learned is this: Vegas doesn’t have LUTs. HOWEVER, there was a workaround. You’ve probably found it or can find it easily. Use Color Curves.

A couple of people have replicated the Cinestyle LUT as an s-shaped curve in Color Curves. You can download it as a preset. I found two different ones that looked almost identical, but still gave different results. Since then, when I’ve shot with the Cinestyle preset, I’ve tried each of the s-curves and just picked whichever of the two looked best at the time.

Short version: I’m guessing you’re using Technicolor Cinestyle or some other “super-flat” capture preset in your DSLR. Some systems use a look-up table to expand the range in editing, but Vegas Pro does not. Use Color Curves instead.

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[Bill Burnette]

Here’s a simple-minded take on LUTs:

In the post production environment, it is important to create a final render that looks right when delivered from a chosen standard color space. A standard color space is a mapping of the digital (R+G+B) values of an image to objective (measurable) color perception (like CIE RGB). Why there should be more than one standard is another story.

One big problem that an LUT solves is that monitors need color correction to display a standard color space in the way that color space intends. Without a proper display, the operator might be inclined to make the wrong decisions about color.

A 3-dimensional LUT can map every color from a given standard color space into an appropriate display color on a monitor. The LUT is matched to the particular monitor; i.e. it is the digital result of calibrating the monitor (after setting whatever controls are built into the monitor hardware). Of course it is (or “should be”) important that the monitor is capable of displaying all the colors included in the standard color space (gamut), otherwise the LUT can only approximate the colors. Sometimes an approximation can preserve the perception of relative colors, but that is another whole story.

Single-dimensional hardware LUTs are part of virtually every PC video adapter, and are supported by the Windows display system. They consist of three rows of 256 numbers, one for red, green, and blue. Those numbers are loaded into the hardware in the video card. The R, G, and B values of each pixel are separately mapped from the image’s value to a value suited for the monitor.

The monitor’s manufacturer probably delivers a standard profile for that model that approximates what the average unit might display when it is new. It is generic for that model and does not address individual differences and aging. Or a profile can be created by a calibration process, like Spyder or ColorMunki, along with a new monitor profile that matches that one monitor (until it ages).

Single-dimensional LUTs can make sure that the monitor displays the right gamma (the curve that relates digital values to relative “brightness”) in R, G, and B. They can also correct color cast in the greys (all the way from the blackest to the whitest that the the monitor can display). But they can’t correct every color, and are sometimes not considered adequate for high-end professional post-production.

There are other uses for LUTs, like mapping from one color space to another, but these are not associated with monitors.

[Ron Whitaker]

I’m starting to get it now.

Why doesn’t Vegas use LUTs?

[Graham Bernard]

_______________________________________________________________

[Ron Whitaker] “Why doesn’t Vegas use LUTs?”
_______________________________________________________________

Ask Sony?

Grazie

Video Content Creator and Potter
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