Different styles, brushes and filters for an image in photoshop.
s you can see, it starts with a simple black and white picture, it's more grey.
If you add filters and / or background shades, the result is very separate in its own ways, a warm filter results in a slightly colourful and human like image, a cold filter like some blue shades are the more Techie way, interessant is the mixing of both styles, this way we have a warm and humane "look&feel" with a tolerable tech touch.
If you combine black background with the #990000 red, you'll get an insane picture at the end, see dna 10.
The same with the brushes, use in different layers, styles and filters, so you're getting various results.