Autodesk 62205-051408-9001 User Guide - Page 615

Working with Logarithmic Image Data ❚❘❘ For example, if you are using Float output, and import a LUT with 10-bit output, the curve switches to 10-bit by default. You can reset it back to Float manually. If the input bit depths are mismatched, then the LUT will scale the LUT input bit depth to match the bitmap input bit depth. Working with Logarithmic Image Data Logarithmic image data is a specialized color space that is used to encode scanned images stored in the Cineon format. This color space simulates how film negative responds to light. The response is logarithmic, so the color space is called logarithmic space. Cineon files are the preferred file format for transferring film to video because of the way the file is stored using 10 bits per channel. This makes it possible to reproduce the full dynamic range of color in film. Linear vs. Logarithmic Color Value Distributions ability to store additional information in the header of the DPX file. Converting Cineon Files to Linear When you import footage, the bit depth is initially set to the bit depth of the footage in the Output controls of the Footage operator. For Cineon files, you can make Combustion automatically convert the files from logarithmic data to linear data and set the linear bit depth. You can leave the bit depth at 10 bits, or change it to 8 bit, 10 bit, 16 bit, or Float. To automatically convert Cineon files to linear: 1. Choose File | Preferences (CTRL+;). 2. In the Footage category, click General. The Footage preferences appear. 3. Enable Log to Linear Conversion. Cineon Import Preferences Progression from Progression from shadows to shadows to highlights is highlights is logarithmic, like linear, like digital video. film and the human eye's vision. The DPX file format is an extension of the Cineon format. Both are 10-bit formats with no compression. Cineon files support RGB channels only (no support for alpha or Z-depth information). DPX files usually are RGB only, but can support alpha. The main difference between the two is the 4. Select a bit depth from the Conversion Depth list. 5. Click OK. Now, if you import a Cineon image sequence, and look in the Output controls of the Footage operator, Use LUT is enabled, and the Depth list is set to the Conversion Depth in the preferences. If you show the LUT Editor controls, you see the conversion method is set to Log to Linear. Since a LUT can be saved inside a Cineon file, the Log to Linear method uses the LUT that is in the file, if available. 599