問80
頻出度★☆☆
ディスプレイ画面の表示では, 赤・緑・青の 3 色を基に, 加法混色によって様々な色を作り出している。赤色と緑色と青色を均等に合わせると, 何色となるか。
平成26年度 春期 ITパスポート試験 問80
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This question's explanation and your answers so far.
解説
問 80
Incorrectア
Magenta (reddish purple) is the color obtained when the two colors red and blue are combined in equal amounts by additive mixing. Green is not included, so it is not the result of combining the three colors in equal amounts. Magenta is also one of the three primary colors of subtractive mixing, so be careful not to confuse it with the three primary colors of additive mixing (red, green, and blue).
Incorrectイ
Yellow is the color obtained when the two colors red and green are combined in equal amounts by additive mixing. Blue is missing, so it cannot be the answer for combining the three colors in equal amounts. That red and green mix into yellow differs from the intuition one gets from paints; it is a result specific to additive mixing, and it is worth remembering that mixing light produces a brighter color.
- ウ
正解 The correct answer is ウ, White. The colors of a device that emits its own light, such as a display, are produced by additive color mixing, which overlays light. The three primary colors of additive mixing are red (R), green (G), and blue (B), and they are called the three primary colors of light. Because additive mixing adds up the energy of light, the more colors are overlaid the brighter it becomes, so combining red, green, and blue at the same intensity in equal amounts gives the brightest state, that is, white. Conversely, if none of the three colors emits light the result is black, and by changing the combination of the intensities of the three colors, all sorts of colors in between can be expressed. It is easier to understand if you recall that a pixel of an LCD display consists of three subpixels, R, G, and B, and that writing a color as #FFFFFF (R, G, and B all at maximum) gives white while writing #000000 gives black. Note that colors seen by reflected light, as with paints or printing, use subtractive color mixing, whose three primary colors are cyan (C), magenta (M), and yellow (Y); the more they are mixed, the darker it gets, and mixing the three colors in equal amounts approaches black. The fact that the result is the opposite of additive mixing is often asked about as a contrast.
Incorrectエ
Verdigris (greenish blue, that is, cyan) is the color obtained when the two colors green and blue are combined in equal amounts by additive mixing. Red is not included, so it is not the result of combining the three colors in equal amounts. Like magenta and yellow, cyan is also a primary color of subtractive mixing, and it is a color that appears when two of the colors are overlaid in additive mixing.
ここがポイント
- Additive color mixing is mixing by overlaying light, and the three primary colors of light are red (R), green (G), and blue (B). The more they are overlaid, the brighter it gets; combining the three colors equally at maximum intensity gives white, and all at zero gives black. Displays, projectors, and other light-emitting devices use this method for their output.
- The colors obtained by combining two of the colors in equal amounts in additive mixing correspond to the three primary colors of subtractive mixing (red + green = yellow, green + blue = cyan, blue + red = magenta). Subtractive mixing takes cyan, magenta, and yellow as its three primary colors, and as with printing or paints, the more they are mixed the darker it gets and the closer to black, which is the opposite of additive mixing, so it is best to learn the two as a pair.
用語