View Full Version : Raw / Rgb / Lut
So just an understanding question
What is RAW / RGB / LUT
i guess you are transforming raw to dpx rgb at the end, right?
and what is a LUT.
how are the relations between these things, and what are they for.
i dont know, i just want to understand
David Newman
10-01-2007, 01:58 PM
LUT = Look Up Table.
Can 1D for RGB curves, or 3D for full remapping of the color space for film stock looks, grading seconardies, etc.
Ross Birkbeck
10-01-2007, 01:59 PM
till,
RAW is a camera format refering to data that is captured off the sensor without any interpretation to turn it into somthing recognisable as an 'image'. It simply encodes what the camera's sensor captures. There are various types of RAW formats - REDCODE RAW is just one of these.
RGB refers to images encoded in three channels - each pixel is made up of a value for red, green, and blue. The combination gives you the final pixel that makes up the final image.
An LUT is a Look Up Table which converts one 'colour space' into another. If you've ever used curves in photoshop then think of that - what that does is create a look up table which says "for this value of the (lets say) red channel we will display this value"
hope that helps - they are actualy all quite different kinds of things (within the maze of digital colourography'
jbeale
10-01-2007, 02:04 PM
I'm not sure what a 3D LUT is. Maybe that means your output channel depends not only the value of that input channel but the other two as well? For example a simple 1D LUT might transfer a Green 23 value to Green 30 (regardless of Blue & Red values). But with a 3D LUT you might have Green 23 mapped to Green 50 if the blue channel there is also high, or Green 20 if the Red channel is lower, etc. (?)
David Newman
10-01-2007, 02:18 PM
Red -> 1D LUT -> New Red
Green -> 1D LUT -> New Green
Blue -> 1D LUT -> New Blue
RGB -> 3D LUT -> New RGB
Single 3D LUT can do everything three 1D LUTs can do, yet it can do a lot more. Most color correction operations (short of power windows) can be described by a 3D LUT. Downside side is there are big. Three 1D 12-bit LUTs, only uses 24KB, whereas a color cube we use for 3D LUT (is 64x64x64 float) at about 3MB. 3D LUTs are more CPU/GPU intensive also.