NAME

rasterfile − Sun’s file format for raster images

SYNOPSIS

#include <rasterfile.h>

DESCRIPTION

A rasterfile is composed of three parts: first, a header containing 8 integers; second, a (possibly empty) set of colormap values; and third, the pixel image, stored a line at a time, in increasing y order.  The image is layed out in the file as in a memory pixrect.  Each line of the image is rounded up to the nearest 16 bits. 

The header is defined by the following structure:

struct rasterfile {
intras_magic;
intras_width;
intras_height;
intras_depth;
intras_length;
intras_type;
intras_maptype;
intras_maplength;
};

The ras_magic field always contains the following constant:

#defineRAS_MAGIC0x59a66a95

The ras_width, ras_height, and ras_depth fields contain the image’s width and height in pixels, and its depth in bits per pixel, respectively.  The depth is either 1 or 8, corresponding to standard frame buffer depths.  The ras_length field contains the length in bytes of the image data.  For an unencoded image, this number is computable from the ras_width, ras_height, and ras_depth fields, but for an encoded image it must be explicitly stored in order to be available without decoding the image itself.  Note that the length of the header and of the (possibly empty) colormap values are not included in the value of the ras_length field; it is only the image data length.  For historical reasons, files of type RT_OLD will usually have a 0 in the ras_length field, and software expecting to encounter such files should be prepared to compute the actual image data length if needed.  The ras_maptype and ras_maplength fields contain the type and length in bytes of the colormap values, respectively.  If ras_maptype is not RMT_NONE and the ras_maplength is not 0, then the colormap values are the ras_maplength bytes immediately after the header.  These values are either uninterpreted bytes (usually with the ras_maptype set to RMT_RAW) or the equal length red, green and blue vectors, in that order (when the ras_maptype is RMT_EQUAL_RGB). In the latter case, the ras_maplength must be three times the size in bytes of any one of the vectors. 

FILES

/usr/include/rasterfile.h

SEE ALSO

Programmer’s Reference Manual for SunWindows

Sun Release 3.2  —  Last change: 14 October 1985