There I’m sitting, at work, the time is 03:22am and for some reason I’m googling pictures of the old boardgame HeroQuest when one image catches my eye. It’s by this guy; Mattias Gustavsson, posted over at RetroGameDev, who has made a pixel shader for a project he’s working on. The shader makes your images look like tmhey are viewed on an old worn-out TV. As it happens, Mattias made an executable of his filter, but unfortunately, it’s for Windows only…

As I’m in love with (or, at least, very fond of) all things retro, this was right up my alley. Clearly, nostalgia is the proof of that you’re getting older.

The picture above is from the Amiga version of HeroQuest, borrowed – without permission – from Kim Lemon’s wonderful site LemonAmiga (also check out his Lemon64 site, if your old enough to remember that one). I ran this image through Mattias’ filter and merged the result with the original as a comparison. I find the latter, with its smoother appearance, much more pleasing to the eye. It’s also more how I remember it looked back in the day when I used to play this game on a crappy old 15″ TV. Not at all those crisp, but dead, pixels you get on a new LCD display.

I would love to have his pixel shader as a Photoshop Action so I could combine it with Philip “Pepto” Timmermann‘s C64 Palette for that full-on, ultra-high, retro feel of 8-bit games.

Above; first one is a guesstimated C64 palette, the second is rendered with the “real” C64 palette (mentioned above), the third one is the same as the second but have had Mattias Gustavsson’s filter applied to it. Now, if that doesn’t take you back, I don’t know what does!

I don’t know how he made it, but if I was to venture a guess, I would say that he first applied a layer of interlaced scanlines on both axis as the picture is twice the size afterwards. Then it seems that the picture is somewhat blured to imitate the not-so-sharp image of a CRT television as well as some color correction and/or color cast. Finally, there is a fair amount of RGB shifting by offsetting the three color channels in different directions. Then again, he could be doing something else entirely. It is, however, one of the more authentic looking effects I’ve seen in a while.

And, while we’re at the topic of old displays, check out Secret Geometry‘s beautiful terminal emulator made as a monochrome monitor. Very Pipboy-ish…

Much to my joy, they also listed a function for calculating ΔE, color difference. More on this subject can be read in this Wikipedia article. Lets just say that I went with the CIE94 (or Delta E 1994 or ΔE94, there doesn’t seem be a formal name for it).

Apparently, to calculate ΔE, RGB has to be converted to the CIE-L*CH° standard. This must be done in several steps; RGB -> XYZ -> CIE-L*ab -> CIE-L*CH°. Kinda tedious…

The picture below is showing different pairs of green shades with each colors RGB value listed at the top and ΔE centered at the bottom of each pair. To quote Wikipedia: “In theory, a ΔE of under 1.0 is supposed to be indistinguishable unless the samples are adjacent to one another.”

As of now, I haven’t yet figured out how to pick new colors. A random pick will yield too many iterations until a suitable color is found. This, however is a small matter. The real challenge will be to come up with a script that would benefit from this.

Apparently, ALL the Commodore 64 emulators out there are mapping the colors somewhat wrong. Philip ‘Pepto’ Timmermann, on the other hand, has made an incredible job to get the colors right. He has a very comprehensive page explaining his method of getting the ‘true colors’ of the c64 here.

A comparison between the emulated colors and the ‘true colors’, as seen below, shows that the latter is much more muted and dull but in fact closer to how the colors were actually processed.

Well, enough of the ol’ c64. There are a lot more swatches but they are much more straight forward so I won’t be going through them all. Here’s just a few.

Amstrad CPC system:

Apple II:

Nintendo 8-bit:

The idea is to limit one selfs creative process by using only the colors provided by each system.

Listed below are all these different systems that are included in my Retro Color Swatch Pack.

• Amstrad CPC
• Apple II
• Atari 2600 NTSC
• Atari 2600 PAL
• CGA
• Commodore 64
• Commodore Plus/4
• Commodore VIC-20
• EGA
• Gameboy
• Mattel Aquarius
• MSX
• Nintendo 8-bit
• Sega Master System
• Teletext
• Thomson MO5
• ZX Spectrum

Very simple, but I do think that it has some nice qualities.

I added some extra features as well. Such as choosing just one singular color R, G, B, C, M or Y. As seen below.

Other options control how many concentric circles there would be (ranging from 1-5 or Random) and a size parameter. As I said earlier this has just been an exercise to help myself overcome some kind of creative block. Better be doing something than doing nothing at all.