A LUT (Look Up Table) is basically a table that says, if the input is a particular colour value make the output another colour, in other words it is just a remapping table – for this colour, remap it to that colour.
In many ways it is similar to the profiles or settings which are designed to correct the colours a television or monitor displays but with a major difference, in that rather than being used to correct colour ranges, LUTs may be used to change tone and colour for artistic effect.
In summary – LUTs can help you with colour grading, but not colour correction.
Generally LUTs may be applied to either colour or mono images, though if one is being applied to a colour image it will probably be necessary to lower the opacity of the LUT layer.
When to use :
As with any other aspect of your post-processing workflow you should use LUTs in a consistent taking care to ensure :
- Images have been properly exposed.
- A proper white balance has been set.
- Other basic adjustments, such as tonal range, levelling, cropping, healing, highlights/shadows adjustments etc have been made.
- Apply the LUT.
- Further refine the image by performing locally targeted adjustments, adding a vignette etc.
LUTs have long been established in the film / video industries, in fact the Teal / Orange LUT (which deepens shadows and lifts skin colours) has almost become a cliche.
Amateur Photographer – What are LUTs and how do you use them?
Lutify.me – LUTs for photographers
Life After Photoshop – How LUTs work in photo-editing