.TH PICFILE 5 .CT 1 inst_info graphics .SH NAME picfile \- raster graphic image format .SH DESCRIPTION Files in this format store images represented as two-dimensional arrays of multiple-channel pixels. A .I picfile consists of an .SM ASCII header followed by binary data encoding the pixels in row-major order. The header is a list of attribute/value pairs separated by newlines, terminated by an empty line. Each header line has the form .IB name = value. The name may not contain an .SM ASCII NUL, newline or .LR = ; the value may not contain null or newline. The last line of a header is empty. .PP The standard attributes are described below; all but .BR TYPE and .BR WINDOW are optional. .B TYPE must come first; otherwise order is irrelevant. As any unrecognised attribute is passed over uninterpreted by all standard software, applications are welcome to include arbitrary annotations, like .BR SHOESIZE=10 , if they wish. .TP .BI TYPE= type How the pixels are encoded. Standard types are .PD 0 .RS .TF runcode .TP .B runcode A run-length encoding. The data are a sequence of .RI ( nchan +1)-byte records each containing a count .I k and .I nchan bytes giving a pixel value to be repeated .IR k +1 times. A run may not span scanlines. .TP .B dump A two-dimensional array of .IR nchan -byte records in row major order. .TP .B bitmap One-bit pixels, packed into bytes high bit leftmost. Zero bits are white, one bits are black. Rows are padded with zeros to a multiple of 16 bits. .TP .B ccitt-g4 A black-and-white image under CCITT FAX Group 4 compression. This format is highly compressive on images of text and line art. Similarly, .L ccitt-g31 and .L ccitt-g32 for Group 3, 1-D and 2-D. .TP .B pico A sequence of .I nchan two-dimensional arrays of single bytes. .TP .B ccir601 Pixels are in dump order, 2 bytes per pixel encoded according to the IEEE digital component video standard. .RE .TP .BI WINDOW= "x0 y0 x1 y1 The .I x,y coordinates of the upper left corner and the point just diagonally outside the lower right corner, .I x increasing to the right, .I y down. .TP .BI NCHAN= nchan The number of channels, default 1. .TP .BI CHAN= value The order of channels. .TP .BI RES= "x y The digitizing resolution horizontally and vertically, in pixels/inch. .PD .TP .B CMAP= (The value is empty.) A color map, a 256\(mu3-byte translation table for color values, follows the header. In a full-color picture, each color-map row maps pixel values of the corresponding channel. In a monochrome picture, pixel values index the color map to yield red, green and blue, like this: .IP .EX unsigned char cmap[256][3]; red=cmap[pixel][0]; green=cmap[pixel][1]; blue=cmap[pixel][2]; .EE .SH EXAMPLES .TP .B sed '/^$/q' image Print a header. A sample header follows. .LP .EX TYPE=dump WINDOW=0 0 512 512 NCHAN=1 CHAN=m RES=300 300 CMAP= COMMAND= antiquantize 'halftone CLASSIC' 512.halftone LIBERTY.anticlassic COMMAND= halftone CLASSIC 512.liberty 512.halftone 1.75 512.halftone COMMAND= transpose IN OUT COMMAND= resample 512 IN OUT COMMAND= transpose IN OUT COMMAND= resample 512 IN OUT COMMAND= clip 400 400 LIBERTY OUT .EE .SH "SEE ALSO" .IR bcp (1), .IR cscan (1), .IR imscan (1), .IR pico (1), .IR flicks (9.1), .IR mugs in .IR face (9.7), .IR rebecca (9.1), .IR flickfile (9.5) .br T. Duff, `The 10th Edition Raster Graphics System', this manual, Volume\ 2