Ultra Fractal Tutorial -- Making High-resolution Renders

by Janet Parke & Kerry Mitchell

If you're going to be printing your fractals you will need to make high-resolution renders of the images. 800 x 600 may be great for your desktop wallpaper or online galleries, but it won't produce a very good (or large) printed image. Here are a few guidelines and tips about this process.

First...

No matter what you're going to do with your fractal, you should first apply anti-aliasing. You can read an excellent explanation of the process here, but the basics are:

• render your image at least twice the size of the desired final dimensions
• export to a graphics program in an uncompressed or lossless format such as .bmp, .tif, .png, or .psd
• re-size to finished dimension
• sharpen to taste (or use an unsharp mask)
• save the file in the desired format

Because anti-aliasing improves all but the softest images, it should be done in all cases where you have the time and space to handle the larger file. An exception is where your finished image size is so great as to make anti-aliasing impractical. Also, for high resolution prints, the effects of anti-aliasing are not as noticeable so for prints printed at 200 pixels per inch or higher, anti-aliasing probably isn't needed.

Making prints with your own Color Ink-jet Printer

If you're going to be printing your images on your home color printer, you'll need to generate an image that is 300 dpi — that is, you want 300 dots per finished image inch. For an 8" x 10" finished image, your rendered image needs to be 2400 x 3000 in size. If you use anything less than 300 dpi, you are likely to see quite noticeable pixelation (dots) in your print. You will probably want to print the image using your printer's highest dpi setting. Be prepared for a small to fair amount of color inaccuracy with these kinds of prints. Some adjustments in color, brightness, contrast, etc. can be made with your printer software and in your graphics program. Each printer is different, so be prepared to experiment to find out what settings work best for you.

All other prints

First of all, check with the photo lab, service bureau, or printer to find out what their specifications are. They will likely tell you the exact dpi and file type needed, along with any other special instructions. Do everything you can to give them your images in exactly the format they request; otherwise, they'll be happy to charge you a hefty set-up fee.

Borders

You should think about whether your image will be matted and framed or displayed, like a poster, without a frame. If you intend to have it framed, you need to allow, either in your image, or by adding a border, room for your framer to overlap the matte and affix the print to its backing. (Check with your framer to find out exactly what is needed.) This should be done on your end. For instance, if I wanted to make a large Lambda digital print for matting and framing, I would zoom out slightly so as to allow ¼" to ½" extra image on each side. Next, I would render the image, multiplying the desired image size in inches by 200. Then I would add a ½" - 1" solid white border within my graphics program (100-200 pixels on each side) and finally, save that entire image in the desired file type. Do note that you will be charged for the dimensions of your submitted file, including borders, not the actual fractal image area.

One other thing...

In case you've never made a mega-render before, the finished file size may astound you. For instance, a 200 dpi file for a 16" x 20" Lambda print comes out to 37 MB. and an 8000 x 10000 image, suitable for making a 4" x 5" LVT transparency for an Ilfochrome print will weigh in at 229 MB. You're going to need a cd-writer to put the file onto CD.

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