The ColourSpace LUT Image is a very powerful tool for direct LUT manipulation, using any graphics program to alter the LUT characteristics.
With this approach any single point from the 35937 LUT points can be directly adjusted (the LUT Image is based on 33^3 LUT data) as the coloured columns either side of the exported LUT image contains all 35937 colours within the 3D LUT. Therefore changing any of the colours within these columns will directly alter the LUT data, when the LUT Image is Imported back into ColourSpace.
LUT Ripping is a very simple workflow and uses the fact that the LUT image can be exported from ColourSpace (with a reference image inserted if required, using Add Picture) and can then have any external colour correction applied. When the LUT Image is re-imported into ColourSpace a LUT will automatically be generated to match the colour changes applied to the LUT Image.
Use LUT Tools/LUT Management/New to generate a new Null LUT, which has no change characteristics (a bypass LUT, where the image data input into the LUT will come out unaltered).
The LUT Image, when Exported, will contain the Null LUT data in the 2 coloured columns within a .tif image.
The chosen reference image can be a standard reference frame, such as Marcie, or a still grabbed from a film or program that represents the desired changes to be made. In this example a desire to lift shadows, without altering the black level, combined with a subtle skin tome adjustment.
The ref image is not a requirement, and has no impact on the LUT, or the manipulations - it is just a guide to help view the changes being made on a real image.
The Exported LUT Image can be loaded into any external system to have the desired colour manipulations applied, such as colour correction setting being used within a grading system. With the grade applied the LUT Image can be re-saved, and loaded back into ColourSpace where a LUT matching the applied grade changes will be automatically generated.
LUT based Workflow Correction
LUT based Corrections can be used to pre-correct image workflows where there is an undesirable change occurring to the image, for example when material is converted via a codec that inherently changes the image colour and/or contrast, including when uploading material to the likes of YouTube, Vimeo, or when using video players such as VLC.
The best approach is to add a selection of different reference images to a number of Null LUT Images, so that any compression applied is variable on each frame.
The images should then be processed through the exact same image path, and the individual images averaged together to null compression artefacts. The final single image can then be loaded back into ColourSpace where a LUT will be generated matching the changes caused by the image processing. This LUT can then be inverted, and used to pre-correct any images before they are processed through the same image path.
LUT Image Manipulation Workflow
The following example shows how a graphics program, such as Photoshop, can be used to direct alter any component of the LUT, using an imbedded image as a visual guide.
Assuming changes are to be made to a calibration LUT, load the LUT into ColourSpace, and add the required reference image, and with the LUT applied to the image, export the LUT Image
Next, load the LUT Image into your desired graphics manipulation program, such as Photoshop, and alter the image as desired, using the inserted reference image as a visual guide to the effect the changes will have.
When the manipulated image is exported from the graphics program the changes will be burnt into the LUT Image, and whne the LUT Image is imported back into ColourSpace, the changes will automatically generate a new LUT.
Another use for graphics program based LUT manipulation is to mix between two, or more, separate LUTs, by using the Layer Reveal capability of such graphics programs.
The concept is simply to place one LUT Image over another, and reveal through the top LUT Image to the second LUT Image below.
The combined layers are then saved as a new LUT Image, and imported back into ColourSpace, as above.