3-bit art

Who remembers Teletext? Knowing our audience, there’s a good chance that you do, but if not, the TL;DR of Teletext is it was a mostly text based data service for tellyboxes back before the signal went digital. (Yes there’s a version now, but it isn’t the SAME!)

It looked like this.

Woo, and yay, that’s a page from our favourite teletext originated thing in the whole world, Digitiser!

So where does this whole 3-bit art thing come in?

You can see in that image that there’s more than just text. There’s blocky pixel graphics too! And colours! And when there’s pixel graphics and colours, someone is going to draw things. And I have! But before I show you what can be done with teletext, let’s explain how the graphics work.

The screen is divided up into a grid of blocks. Each block can hold either one character, one set of 2×3 pixels, or one control code. Blocks can’t hold colour information AND a character or graphics at the same time. You have to set the colour using a control code, and then go on to draw in the colour. So if I wanted to draw some things in red, the blocks would look like this:

Televisions would read those blocks from left to right, they’d see the control code saying “Hey, you’re going to be drawing Red Flavour Graphics now!” and then they’d switch into the right mode for drawing red pixels.

Unfortunately, that means the block with that R control code can’t have anything else in it. It’s an empty, black block on the screen. Which makes it difficult to have two colours next to each other. If you want two colours next to each other (wow, sheer luxury) then you have to set a background colour, start a background, and then switch to a different colour, which takes three control codes in all! And it looks like this:

Setting blue graphics, starting the background, and then switching to red graphics.

Tricky enough right? Surely that’s the end of all trickyness. No! You see, the middle row of pixels in those graphics blocks are not square like the top and bottom rows are. They’re taller. Isn’t that great?

Oh, and you have red, green, blue, magenta, cyan, yellow, and white graphics. You can’t draw in black. That’s where the 3-bit comes from. You’ve heard of 16-bit graphics? 8-bit graphics? Well, with 3-bit graphics, those 7 colours are all you get.

With all of those restrictions, why bother? Because it’s fun. It’s frequently more like solving a sudoku puzzle than drawing a picture. And when you get something that looks good, the small but appreciative teletext art community heap praise upon you, and if I don’t get constant praise I feel bad.

Anyway. You came here for the pictures didn’t you. So here’s what I’ve been able to do so far!

I’m particularly proud of the Gamora image, because of how I had to find ways to hide the control codes around the eyes, and still be able to recognise her. Here’s what it looks like with the blocks and control codes visible.

Hopefully that’s been interesting, and explains why I’ve been so excited when I finish one of these!

Published by

notnownikki

Nikki's just this gal, you know?

5 thoughts on “3-bit art”

  1. When you get a bit more used to it, look into using separated graphics, too. It can add another level of texture where the solid colours are a bit harsh and without dithering.

    Then, try playing with the Hold Graphics code. This WILL allow you to place different coloured blocks next to each other, but it does so by repeating the previous character in place of the blank. It’s powerful, but can be tricky to use.

    Enjoy!

    Liked by 1 person

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