Graphics
Interchange
Format, please
>- click -<
on image below to see the flashes in animation.
- Path-n-Light-Tracing_Pyramid,-Sphere,-Cube-and-Cylinder
120 tiny frames of 326 x 183 Pixels rendered in about 24 minutes.
That's only 59.7 kPx what equals 2.88% of an image of, rather soon obsolete, HD TV screen.
Even an Apple Watch 5 with 44 mm case displays with 448 × 368 Px a total 164.9 kPx (RGB).
This again means tiniest 495'000 LED, not to mention their controller circuitry and wiring.
Somewhen 1987 I caught a harmless virus called ray tracing one home computer.
This is how it looked like. { >- click -< to view animation }
- The Juggler (Amiga, Commodore) - (c) 1986-11, Eric Graham (CC BY-NC-ND 3.0)
Dimension: 320 x 200 | Colors: 4'096 HAM-6
Frames: 24 | Type: ANIM-5 + SLA (anim with audio)
ANIM version by Walter and Werner Randelshofer
A special 6 bit mode called HAM (Hold-And-Modify) displayed up to 4096 colors leading to unbeatable image quality in widely used and very common TV screens (NTSC or PAL). In those days the product of vertical and horizontal frequency was about the same for both TV systems. Interlaced flickering half frame frequencies depended on main power's frequency (USA 110 Volts @60 Hz, Europe 220 Volts @50 Hz). Progressive resolution was in the USA 320*200 Px, in Europe 320*256 Px.
Interlaced maximum resolution was visible on good CRT PAL monitors with up to 704*576 Px (overs-can mode). This equals 20.275 MPx/s, 101.375 Mbit/s respectively (32 colors, 5 bit). Given a 16 bit data bus this leads to 6.34 MHz. If compared to system's clock frequency of 7.2 MHz there were some clocks left for other operations on Amiga's own chip set (Paula, Denise, Agnus) than translating x bit color palette to 6 bit RGB for the input of video DAC.
However, 4096 colors would require 12 bit (3x4 bit). Indeed one could always chose from 4096 colors by defining a RGB values, each color channel with a range from 0 to 15, but usually this was limited to 32 colors palette. The 1985/1987 Amigas displayed 32 colors from 4096 simultaneously but there had been some trick to display much more than 32 colors on video screens, although with some more or less annoying limitations.
In HAM mode registers for 12 bit colors was limited to 6 bit for each horizontal line (electron beam's scan line). 2 bits (control) defined one of 4 cases the other 4 bits (data) meant. In one case a color out of 16 was used (hold) in the other three cases two RGB channels got the values from the previous pixel (left sided) and one color channel got a new 4 bit value (modify).
This rather special color mode was historically owned to YUV instead of RGB color space. Controlling YUV (TV, video) HAM made much more sense but RGB had other superior properties for computer graphics.