Do you mean one of the coloured images or the image manipulation of a fighter jet (or both)?

The second image looks like the most difficult to emulate becaue of the 'hairy' texture. Take a look at some of the code on OpenProcessing.org or in the examples that ship with Processing to ideas as to how to achieve various effects.

According to the original artist Jonathan Zawada's website processing was indeed used for some works, although it is not clear for which ones.

The fighter is just some pixel manipulation. You can see it from the image. A single vertical line of pixels is stretched to like 200 pixels, like you could do in Photoshop. However within this range the whole image is tilted/turned upside down. The lower pixels turn faster than the upper pixels. You can see this effect even better in another one of Jonathan's works here. To do this you can use the pixel array. See here and here for inspiration.

The second image seems part analog or at least have an analog source image. To create such a hairy effect you can take the pixel's color as input and draw a line at the x,y and then change the color, rotation, length etc. according to the pixel's color. See a basic example here.

The other ones don't look like they were made with Processing.