Format .cin was developed by company named Kodak. Its whole name is Cineon, this name is derived from name Cineon System. It was graphical program working especially with movies. This system was eliminated a long time ago, but format Cineon is used as provider of visual effects till today.
Format was introduced in 1993 together with Cineon System and moreover it was very advanced file type of its time. Its advantage was ability to use 2K and 4K resolution, which overtook its time. However in 1997 was System eliminated, but it was saved till today and file type is still in use. Format was created by default for creation of scanned movies, it was also used at the creation of animated film called Snow White and the Seven Dwarfs by Disney. Every scan was uploaded to pcs and completed in Cineon System. Whereas it was declined, you have to use other programs to open files from this format.
Adobe Photoshop is the right choice, if you want to open these files. It isn´t for free, but this application has trial version, which is 30-days long.