I got a message from Ville Jouppi stating that the original Kickstart screen was created by Sheryl Knowles. Seeing that her initials are S.A.K. we figured that she must also have been the artist behind the SAK images.
At the same time there was Jack Haeger with the Commodore team and with a little imagination the ljl Signature can look like his initials J.H.
I renamed SAK and LJL to the proper names and also regrabbed the Amiga Boing Ball Demo image. While looking at it closer I found out that it was put together pretty cleverly.
The Amiga Boing Ball demo was created during a night at the 1984 CES by Dale Luck and R. J. Mical and it is told that show visitors completely blown away by this.
The demo itself was a very clever demonstration of how it's custom chips could be used to fake an effect rather than to create it with pure processing power.
In reality nothing on screen is redrawn during the demo.
The ball itself is rendered at the beginning of the demo and then 'animated' with the color cycling method.
The motion of the ball is done by moving the scroll positions of the different bitplanes. It uses 3 bitplanes, while the grid uses another bitplane and the shadow uses the last bitplane.
The clever selection of color registers makes it possible to have a shadow that works correctly with the grid while not interfering with the ball. This is also the reason why this image needs 32 colors and why the color palette contains mostly duplicates.
All this means that the demo does full hardware scrolling, costing next to no cpu processing power.