In addition, even LUTs claiming to fit your needs may be technically inaccurate, aesthetically displeasing, produce image artifacts, or some combination of all three. LUTs are designed for a range of overlapping applications, and finding the right one for your specific needs requires some know-how. While the concept of a LUT is very simple, its practical deployment in post-production workflows is more complicated. Why is there so much confusion and contention surrounding LUTs and their usage? We have to go to it it will not come to us. We can’t tell it what kind of image to expect, or specify anything about what we’re expecting back from it. LUTs are dumb. In addition to having no need for human input, a LUT has no way of receiving it.Applied properly, this produces far more efficient and consistent results than a human operator trying to replicate the same process. LUTs are automatic. A LUT doesn’t need human input, and can be placed in the pipeline of 1,000 shots as quickly as it can be placed in one.This makes for small file size, lighter processing needs, and can produce an image visually indistinguishable from one transformed by reading and manipulating every single pixel. LUTs are based on the idea of sampling. Rather than storing output values for every possible input value, they take and modify samples at regular intervals, and use a mathematical formula to estimate the values in between.While a LUT’s color transformations can come in many forms and be applied in several ways, all LUTs have the following basic traits in common: This results in a change in contrast, color, or both.
A set of values is sampled from the incoming image, and these values are modified according to the numbers stored in the table. What is a LUT?Ī LUT, or lookup table, is a list of numerical values used to transform an image’s contrast and/or color. That’s it.
DEFINE LUT HOW TO
In this article, we’re laying out everything you need to know about LUTs, from the technical basics of how to use them correctly, to our top tips that will boost the creativity and speed of your workflow. But as is the case with the dozens (or hundreds) of other acronyms that get thrown around in this industry, the meaning of the term is not always clear to everyone.īut even if you know what a LUT is, you might not know exactly how to use them correctly, their benefits, or their limitations. I feel like it’d be useful to add a couple parameters that define how to encode the RGB data going into the LUT and another for how to interpret the output data from the LUT.If you’ve spent at least 10 minutes in a post studio within the last few years, odds are you’ve heard the term “LUT” used a time or two. I assume it has to process the data from LR Internal working space > some RGB > LUT > Interpret RGB DATA > Convert for display icc. How does ACR/LR interpret the RGB data after it’s run through the LUT? What specifically is this referring to? The RGB data being input, output?įor instance if I have a LUT that converts Rec709 Gamut/sRGB Gamma -> Rec709/Cineon > Kodak 2383/Rec709 Emulation would I select space: srgb/clip?īasically do I need to make my LUT loop back into whatever colorspace I define in ACR? For instance ProphotoRGB/Gamma 1.8 -> Rec709/Cineon -> Kodak2383/Rec709 Emulation -> ProphotoRGB/Gamma 1.8. I commented on Julieanne Kost's blog post about it as well. I'm guessing that encoded LUT represents the specified LUT, converted to the working space of ACR (MelissaRGB). xmp file, the color space isn't recorded anywhere, just an encoded LUT. No, the enhanced profile containing the LUT can be applied to any image that ACR / LR can read. "if you use such a LUT, does one have to use them only on images that are in the same color space (seems that wouldn’t be necessary with raws that have to be encoded into something at some point)."
A Rec 709 LUT applied to an sRGB image will often / usually result in an image acceptably close to that LUT applied to the Rec 709 version of the image, though I can often see differences in the shadows, as you'd expect. SRGB is pretty close to Rec 709, with the same primaries but modestly differently gamma encoding. "So what happens if the color space isn't in sync? That is, you pick sRGB or ProPhoto but you want Rec 709? Like with ICC profiles, does that screw up the color appearance?"
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