Short: IFF-YUVN alpha extension (DATO) Author: info@ar-kleinert.de Uploader: info ar-kleinert de Type: docs/misc Version: 1.1 Architecture: generic Previously, the IFF-YUVN file format supported the following image data formats basically: YUV 400 YUV 411 YUV 422 YUV 444 YUV 200 YUV 211 YUV 222 by means of separate chunks for Y, U and V. Now the following - as a consequent logical extension of the previously mentioned definitions - is introduced by SView5-Library: AYUV (for all of the previously mentioned) by means of adding an additional chunk for standard A(lpha) information. Following the naming traditions for the other chunks the new chunk is called "DATO" - in order to avoid overlaps with older definitions "DATA" could not be used: there already existed a predecessor called "DATA" which supported only alpha values in the range 16..235). The O in DATO stands for opacity. The contained alpha information always needs to be provided for each pixel of the image, thus DATO always contains [width * height] alpha pixels, which is the same dimensional size as for DATY. Assuming a bit depth of 8, the size is exactly the same. The meaning of each 8 bit alpha value is the same as with PNG alpha channels, i.e. 0x00 = fully transparent, 0xFF = fully opaque. Typical file structure: ID_YCHD ID_NAME // optional ID_AUTH // optional ID_ANNO // optional ID_Copy // optional ID_DATO // optional (A)lpha information ID_DATY ID_DATA // optional (16..253 alpha values) ID_DATU ID_DATV (*) use either DATO or DATA, but not both