If you don't specify a size, the image will default to the size of your display, assuming it was able to connect to your display. Provided for backward compatibility. Normally, the gradient will be the size of the image. Normally, the gradient is aligned vertically, with the first color at the top, and the last color at the bottom. Using this option, you can rotate the whole mess by an arbitrary amount.
Positive values rotate the gradient counter- clockwise.
If supplied, bggen will generate a PPM 'ascii' file, rather than the default PPM 'raw' format. It must range between 1 and 8, inclusive. Since xv can do this sort of thing better, this is of dubious value. This is a little X program I wrote years ago to help me debug xv 's color allocation code. It can give you an indication of how full your colortable is, and whatnot.