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FractalEscape is a simple, escape-time fractal generator. To compile it, just run make. You will need libpng installed. Running it without options will print usage information. Some notes about the model it uses will help make sense of the options. For this program, each 'fractal' is a 12 parameter polynomial. Those 12 parameters are represented as a string of 12 characters, each of which encodes a number. This string can be specified using the -f/--fractal option, or can be generated randomly (more on that below). The fractal is rendered by estimating escape times for points in a rectangular grid. This grid is determined by the -s/--size and -c/--coords options, which specify the pixel size of the output and the real number coordinates of the rectangle. FractalEscape will happily accept output dimensions of a different aspect ratio from the real coordinates. The output can be tweaked in two major ways. First is a scaling option -m/--maxval. This will rescale the range of escape time values to fit into a predefined range of output values. The other major tweak is oversampling (a.k.a. anti-aliasing). Activating the -O/--osfact (that's a capital letter O) option will cause a grid of NxN values to be computed and averaged for each output pixel. A value of 2 or 3 vastly improves the visual quality of the output. Larger values do not have much benefit. Output is saved as PNG images, by default named based on the 12 character string defining the fractal (so that you can easily regenerate a fractal with different tweak parameters later on). If generating only a single fractal (i.e. using the -f/--fractal option), you can specify the filename with the -o/--output option. If generating multiple fractals (random mode), that option will instead specify what directory to save all the images into. Random generation of fractals is activated with the -r/--random option. This can optionally take a number of fractals to generate. If not specified, it will generate fractals until it receives an interrupt (Ctrl-C), at which time it will clean up and exit gracefully, trying hard not to leave broken, half written images in its wake. The process of generating random fractals goes like this: - While not enough images have yet been generated ... - While not enough candidates for the next image have been analyzed ... - Pick a random set of values for the 12 parameters - Check the escape time at the 0,0 pixel - If it doesn't look boring (doesn't escape too fast) ... - Compute a thumbnail (1/10th width & height, no oversampling) version of the fractal, passing it through a statistics collector. - Compute an 'interestingness' score - Save the parameters and score - Generate at full resolution the best candidate we found Currently "enough" candidates is 100, "enough" images is determined by the --random option as described above. The 'interestingness' qualification at step 3 works off the rough observation that fractals that have too little or too much going on (all the same value, or white noise) are uninteresting. The scoring for this works something like this: 1) Mark the most common pixel values as likey background 2) Figure out how many of the next most common pixel values it takes to consume 2/3rds of the image. Positively score values in what I empircally determined to be a 'good' range, negatively score values outside that. 3) Weight the score based on the fraction of the image area that was marked as likely background -- the greater the portion of the image that is taken up by background, the more boring the image is. Cheers, -- Matthew "Cheetah" Gabeler-Lee firstname.lastname@example.org