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The ZX Spectrum is generally considered to have limited graphical capabilities in comparison to some other home computers of the same era such as the Commodore 64, largely due to its lack of a dedicated graphics chip. Nevertheless, throughout its commercial life and later activity on the demoscene, various techniques have been developed to provide (or emulate) improvements to the Spectrum's graphical output. ==Color palette== The ZX Spectrum (and compatibles) computers uses a variation of the 4-bit RGBI palette philosophy. This results in each of the colors of the 3-bit palette having a ''basic'' and ''bright'' variant, with the exception of black. The ''bright'' half of the palette is generated using the video display's maximum voltage levels for each of the three R/G/B color components that a color uses. The ''basic'' half of the palette is displayed by simply reducing these voltages. Unlike most RGBI palettes, the ZX Spectrum swaps the color components around a bit: Blue has a binary weight of 1, Red has a weight of 2, while Green has a weight of 4. As with any binary number, these weights add up to produce a single decimal number that matches the displayed color, the effect of which can be seen in the table below (pay special attention to the "binary value" column). For any value of ''n'' from 0 to 7, the following commands can be used to set or alter the screen's colors: * BORDER ''n'', the color for surrounding area outside the main bitmap. * PAPER ''n'', the background (pixel bit value of 0) color for the color cell to be altered. * INK ''n'', the foreground (pixel bit value of 1) color for the color cell to be altered. Furthermore, the BRIGHT command can be used to change the setting of the PAPER and INK commands' "bright" flag (the ''I'' in RGB''I''), giving them access to the entire 15-color palette. Settings of "0" and "1" turn bright mode off and on (respectively). Since only one bit within a color attribute byte is used to select the brightness for both foreground and background colors in a color cell, it is not possible to select both ''bright'' and ''basic'' color modes in the same color cell. The BORDER command does not use a bright flag, thus only the eight ''basic'' colors are supported. Counting from least to most significant bit, an attribute byte dedicates three bits for the foreground color, three bits for the background color, one bit for the bright flag, and one bit for the flashing effect (which causes the video display to alternate foreground and background colors periodically). : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ZX Spectrum graphic modes」の詳細全文を読む スポンサード リンク
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