DNA Blobs

Click on these pictures to see a larger version...	... and read this text to learn how to create this effect.
This exercise hinges on use of the gradient fill tool. Select the gradient fill tool, with white as your active (start) colour and black as your alternate (end) colour. Select the radial fill gradient type. Next, set the Merge Mode to If Lighter (this might go under a different name in packages other than Picture Publisher - refer to your manuals for information). The "If Lighter" mode is crucial to achieving the effect we want. It allows blobs to overlap and merge into one another.
	Now draw some gradients. Looks boring huh? Draw more...
	After much blob-drawing, you should end up with an effect similar to this. Nice... but still very plain.
	To inject some colour into the picture, you can colourise the blobs (use Hue Shift in Picture Publisher). You may need to increase the colour saturation, then just pick a nice colour and go. The blobs on the left are colourised in this manner - but to make it more attractive, I created a gradient mask from to left to bottom right corner. I then colourised the masked area blue, increasing the saturation lots, inverted the mask, and colourised the new masked area green. This makes the green-blue blobs fade into each other.
	An alternative to the hue shift would be to either use a normal brush in colourise mode, or alternatively try drawing blobs using different start colours. The blobs on the top left were drawn using starting colours of red and yellow. The picture on the bottom left is the same, but I've applied a gaussian blur to smooth it out a bit - the blobs look quite unnatural where the different colours meet otherwise. (Note that this difference doesn't show up very well unless you have a 16-bit or 24-bit display.)