AIS stands for Array of Intensity Samples. The AIS file format is a digital encoding of images. Each AIS file is a digital representation of a rectangulat array of pixels ("picture elements"). The array is a sequence of scan-lines, each of which is a sequence of pixels. Each pixel is described by one ore more samples -- more than one sample is required whenever several signals (e.g., chromatic separations) are to be represented in the same file.

The AIS format accomodates images of different sizes, different resolutions, different intensity quantizations, different numbers of signals, etc. A header on the file describes the various parameters of the file, called the attributes. The AIS format can also accomodate different methods of encoding images, but only one such encoing has been defined and implemented to date: an uncompressed array of signal samples (UCA encoding).

Refer to [Indigo]<AltoDocs>AISManual.press for a description of the details of the AIS format, if you care.

Refer to the file AISTest.mesa (obtained via the DF file) for some simple examples of programs that read and write AIS files.

CedarGraphics may be used to display certain kinds of AIS files. It is not very fussy about the details in the header, and as a result there are some AIS files around that don't really conform to the AIS format, although they display with CedarGraphics just fine. AISImpl may complain about these files; contact a wizard if you have trouble.