Amiga Halfbrite mode
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" />