Amiga Halfbrite mode
Extra Half Brite (also referred to as Extra-Half-Brite or Extra-Halfbrite) usually abbreviated as EHB,[1][2][3][4] is a planar display mode of the Amiga computer.
This mode uses six bitplanes (six bits/pixel).[3][5][6] The first five bitplanes index 32 colors selected from a 12-bit color space (4096 possible colors). If the bit on the sixth bitplane is set, the display hardware halves the brightness of the corresponding color component.[7] This way 64 simultaneous colors are possible (32 arbitrary colors plus 32 half-bright components) while only using 32 color registers.[8] The number of color registers is a hardware limitation of pre-AGA chipsets used in Amiga computers.
Some contemporary game titles (Fusion,[9] Defender of the Crown[10], Agony,[11] Lotus II[12] or Unreal[13]) and animations (HalfBrite Hill[4]) used EHB mode as a hardware-assisted means to display shadows or silhouettes.[9][14] EHB was also often used as general-purpose 64 color mode with the aforementioned restrictions.[9][15][16][17]
Some early versions of the first Amiga, the Amiga 1000 sold in the United States lack the EHB video mode, which is present in all later Amiga models.[4][2]
See also[edit]
References[edit]
- ^ Mortimore, Eugene P. (1986). Amiga Programmer's Handbook. SYBEX. ISBN 978-0-89588-343-8.
- ^ a b Maher, Jimmy (2018-01-26). The Future Was Here: The Commodore Amiga. MIT Press. ISBN 978-0-262-53569-4.
- ^ a b "Amiga® Hardware Reference Manual: Color Selection in Extra Half Brite (EHB) Mode". Amiga Developer Docs. Retrieved 2022-11-19.
- ^ a b c Sullivan, Kevin (1987). "HalfBrite Hill". Amiga Animations. Blair-Sullivan Computer Graphics & Animation. Retrieved 2022-11-19.
- ^ "The Atari ST and Amiga computing evolution!". Retroshowcase: oldschool game reference!. Retrieved 2022-11-19.
- ^ Peddie, Jon. "Amiga (1988)". IEEE Computer Society. Retrieved 2022-11-19.
- ^ Maher, Jimmy (2018-01-26). The Future Was Here: The Commodore Amiga. MIT Press. ISBN 978-0-262-53569-4.
- ^ Amiga ROM Kernel Reference Manual: Libraries. Addison-Wesley. 1992. ISBN 978-0-201-56774-8.
- ^ a b c "Extra Half Bright (EHB)". Amiga Graphics Archive. Retrieved 2022-11-19.
- ^ "Defender of the Crown - Castle Norman - Amiga Graphics Archive". amiga.lychesis.net. Retrieved 2023-04-12.
- ^ "Agony - Loader 1 - Amiga Graphics Archive". amiga.lychesis.net. Retrieved 2023-04-12.
- ^ "Lotus 2 - Level 1 - Forest - Amiga Graphics Archive". amiga.lychesis.net. Retrieved 2023-04-12.
- ^ "Unreal - Amiga Graphics Archive". amiga.lychesis.net. Retrieved 2023-04-12.
- ^ "Enhanced Graphics - Extra Half-Brite (EHB) Mode". Hall Of Light - The database of Amiga games. Retrieved 2023-04-12.
- ^ "EHB images". Amiga Graphics Archive. Retrieved 19 September 2011.
- ^ Compute. Vol. 11. Small System Services. 1989. pp. 44, 53.
- ^ Kroah (2020). "The Bard's Tale serie - Bard's Tale Construction Set". Kroah's Game Reverse Engineering Page. Retrieved 2022-11-19.