Amiga Halfbrite mode

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File:32 vs Ehb64.png
A normal 32 color image can be compared to an Extra Half Brite 64 color image.
File:Ehb64.png
Extra Half Brite 64 color mode picture
File:32c.png
Normal 32 color mode picture

Extra Half Brite (also referred to as Extra-Half-Brite, Extra-Halfbrite, or EHB),[1][2][3][4] is a planar display mode of the Amiga computer.

This mode uses six bit planes (six bits per pixel).[3][5][6] The first five bit planes index 32 colors selected from a 12-bit color space of 4096 possible colors. If the bit on the sixth bit plane 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 using only 32 color registers.[8] The number of color registers is a hardware limitation of pre-AGA chipsets in Amiga computers.

Some contemporary games (Fusion,[9] Defender of the Crown,[10] Agony,[11] Lotus II,[12] or Unreal[13]) and animations (HalfBrite Hill[4]) use EHB mode as a hardware-assisted means to display shadows or silhouettes.[9][14] EHB is often used as general-purpose 64 color mode with its own 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

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References

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