The end result of running rayshade is an image file. Depending upon how it was installed, rayshade writes images in either the Utah Raster RLE format or a generic but easily-manipulated mtv format used by Mark VandeWettering in his mtv ray tracer. The mtv format consists of a header giving the resolution of the image followed by interleaved red-green-blue values for each pixel. The RLE format supports an arbitrary number of color channels, an alpha channel, comments, a history field, and the ability to treat images as windows into a larger image. As a result of this flexibility, a number of rayshade's features are not supported if the mtv format is being used. You are thus strongly encouraged to obtain a copy of the Utah Raster Toolkit.
If the mtv format is used, the image will (and must) consist of three eight-bit color channels. If the RLE format is used, the image file consists of three eight-bit color channels plus an eight-bit alpha channel. Rayshade also documents in the RLE header the command line and gamma value used in creating the image.
If more than one frame is rendered, the resulting images are appended in turn to the image file. The various utilities provided by the Utah Raster Toolkit can be used to manipulate the resulting ``movie'' files. If the Toolkit is not being used, you will probably need to write utility programs to handle the decidedly non-standard multi-image mtv format files.
By default, rayshade writes the computed image to the standard output. The image file may be written to a file instead by specifying a file name in the input stream.
The size of the output image is measured in pixels. The x size is the number of pixels left-to-right, while the y size is the number of pixels bottom-to-top.
When rendering an image, it is often advantageous to split the image into a number of disjoint windows, each of which is rendered on a different machine. One then combines the images corresponding to the windows into a final image.
It is also convenient to be able to render a small portion of the window by specifying a subregion using normalized coordinates.
The Range Map or Z Buffer output file will also obey the screen, window and crop commands.
Gamma correction may also be applied to the three output color channels.