Now we're talking. You prompted my 90's Mac memory banks and I vaguely recalled there was an EVEN easier way to display a full screen custom startup image. After a quick googling, this post over at 68kmla
Just place a "PICT Resource" file named StartupScreen in the System Folder and it replaces the usual happy Mac and progress bar. You still see the icons loading. You can even use a "StartupMovie" file to play a QuickTime movie at boot.
I used Photoshop 3.0 to save a TIFF screenshot of Sierra booting and saved as a "PICT Resource" (32bit).
Here's Mac OS 8.6 booting (in SheepShaver) with a "Sierra themed" startup screen.
View attachment 713415
Next is to get a screenshot of System 7 booting and pop it in the System Folder.
[doublepost=1503048482][/doublepost]...And for a quick bit of trivia, Mac OS 8.6 was codenamed "Veronica" according to wiki
Want this black "Sierra" startup screen for Mac OS 8/9? Download and unzip/unhqx/unstuff the attached SierraStartup1024x768.sit.hqx.zip
. Drop the "StartupScreen" file into your System Folder.