Amiga Halfbrite mode

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),<ref>Template:Cite book</ref><ref name=":0">Template:Cite book</ref><ref name=":2" /><ref name=":3" /> is a planar display mode of the Amiga computer.

This mode uses six bit planes (six bits per pixel).<ref name=":2">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref>Template:Cite book</ref> This way 64 simultaneous colors are possible (32 arbitrary colors plus 32 half-bright components) while using only 32 color registers.<ref>Template:Cite book</ref> The number of color registers is a hardware limitation of pre-AGA chipsets in Amiga computers.

Some contemporary games (Fusion,<ref name=":1" /> Defender of the Crown,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Agony,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Lotus II,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> or Unreal<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>) and animations (HalfBrite Hill<ref name=":3" />) use EHB mode as a hardware-assisted means to display shadows or silhouettes.<ref name=":1">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> EHB is often used as general-purpose 64 color mode with its own restrictions.<ref name=":1" /><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite book</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

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.<ref name=":3">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name=":0" />

See also

• Original Chip Set
• Hold-And-Modify

External links

• Animated demo using Halfbrite mode (requires Java)
• Amiga Graphics Archive - Extra Half-Brite