Short: IFF-DEEP 48/64 Bit extensions Author: info@ar-kleinert.de Uploader: info ar-kleinert de Type: docs/misc Version: 1.1 Architecture: generic Previously, the IFF-DEEP file format supported the following image data formats basically: 24 bit -> as RGB 8:8:8 true color pixels 32 bit -> as RGBA 8:8:8:(4/8) true color pixels + alpha In addition to RGB also other color spaces are supported and the sample order could vary. Basically any kind of bit depth is possible - but yet uncommon. Bit depths also could vary for each sample. For compression, only uncompressed, RLE and DELTA are common. For DELTA, instead of single pixels (all samples alternating in a row) separate lines per sample are stored for a row. Now the following - as a consequent logical extension of the previously mentioned definitions - is introduced by SView5-Library: 48 bit -> RGB 16:16:16 true color pixels 64 bit -> RGBA 16:16:16:16 true color pixels + alpha With regards to the Alpha channel it is considered legal to load/save/interpret only the upper 8 bits, thus leading to effectively 56 bit depth - however generation of 56 bit files is considered uncommon. Instead, prior to loading/saving, the 8/16 bit alpha channel should be properly scaled up/down to 16/8 bit. For compression this means: - uncompressed: no change (raw buffer size) - RLE: multiply "bytes per line" by 2; compress on byte-level - DELTA: multiply "bytes per line" by 2; lookup table remains 16*WORD; delta is relative to UWORD instead of UBYTE - other: to be defined