bLUe proposes a modular and comprehensive GUI for photo edition, featuring a large set of controls as adjustment layers, including 3D LUTs, 2.5D LUTs and curves in various color spaces.
A 3D LUT is a table representing a 3D cube of color nodes. Image pixels are associated
with nodes, based on their color. Changes are applied to each node individually,
giving full control over colors. When changes in color do not depend on the pixel brightnesses,
the table is called a 2.5D LUT. bLUe can create and edit 3D and 2.5D LUTs. read..
2.5D LUTs are edited by selecting, grouping and moving nodes as control points over
a (hue, saturation) color wheel. Nodes are bound to an elastic grid and a grid smoothing algorithm is provided
to even the changes in color. Selection masks are automatically created from 2.5D LUTs, based on the node selection.
Masks can be freely edited.
3D LUTs are controlled by curves defining changes (additive or multiplicative shifts)
in a color channel, depending on the value of another channel.
The 2.5D LUT grid editor allows quick corrections of the whole range of colors in an image and, at the same time, precise modifications of a group of selected color nodes.
For each group of color nodes the editor allows the edition of the brightness curve and thresholding : changes in colors are limited to a range of brightnesses and the brightnesses of colors in the group are corrected according to the curve. Other colors keep their initial brightness.
A quick moonlight effect only using two groups of nodes.
See the tutorials for a complete description.
