It's too small to be officially accepted by dA as a wallpaper, but it's exactly one-half the width and one-half the height of a 1024x768 screen -- you can actually stretch it and not be able to tell that it's stretched. <br />
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I created a multi-color (actually grayscale) gradient in an alpha channel, copied the alpha channel to the red channel, flipped the copy and pasted that to the green channel, decided to leave the blue channel alone, then used the "mosaic" method to tile the result to 512x384 size (the original tile was 256x192).