Introduction
CTB is the print job format written by Chitubox, the slicer for resin printers made by CBD-Tech, whose control boards are used in many low-cost resin printers from makers such as Elegoo, Anycubic and others. Like other resin formats it holds one image per layer, to be shown on the printer’s screen, with the exposure and movement settings for each layer.
The format is proprietary. Recent versions encrypt parts of the file, and third-party tools that read it rely on work done by studying the files.
Structure
A CTB file is binary. It starts with a header giving the format version, the printer and print settings, and the positions of the other parts of the file. Two preview images follow, then a table of layers, each with its height, exposure time and the position of its image. Layer images are compressed with run-length encoding, which suits pictures that are mostly solid black and white.