METHOD OF DEVELOPING, MEASURING AND NAMING COLOUR.
The single sensation colours, Red, Yellow and Blue, are matchable by a single glass from the corresponding colour scale; the depth of colour is directly indicated by the value of the glass used.
The single sensation colours, Orange, Green and Violet, are matchable by a combination of equal units, from two of the standard scales, the depth of colour is directly indicated by the unit value of either of the glasses, thus: 2·0 Blue + 2·0 Red develop 2·0 units Violet.
A given neutral grey is matchable by a combination of equal units from the three standard scales, the depth of grey, is directly indicated by the unit value on either of the glasses used, thus:—
3·0 Red + 3·0 yellow + 3·0 blue develop 3·0 units neutral tint.
The complex colour sensations, red and yellow oranges, yellow and blue greens, blue and red violets are matchable by unequal glasses from two of the standard scales; the colour developed is not directly indicated by the unit value of the glasses, but is recorded by means of an equation, the first half of which contains the separate values of the glasses used, and the second half the names and the depth of the colours they transmit. For instance—
The equation of a colour matched by 17·0 red and 2·6 blue units, is as follows:—
Standard Glasses. Colour Developed.
Red. Blue. Violet. Red.
17·0 + 2·6 = 2·6 + 14·4
The colour developed is a red violet in these proportions.
A colour matched by
Standard Glasses. Colour Developed.
Red. Yellow. Orange. Red.
10·0 + 3·0 = 3·0 + 7·0
The colour developed is a red orange in these proportions.
A colour matched by
Standard Glasses. Colour Developed.
Yellow. Blue. Green. Yellow.
3·0 + 1·5 = 1·5 + 1·5
The colour developed is a yellow green in these proportions.
A colour matched by
Standard Glasses. Colour Developed.
Blue. Red. Blue. Violet.
6·0 + 1·8 = 4·2 + 1·8
The colour developed is a blue violet in these proportions.
The standard glass colours are necessarily of a given brightness, and colours for measurement may be either brighter, or sadder than the standards.
A given complex colour of less than glass standard brightness, is matchable by unequal numbers from the three standard scales; the smallest unit value always represents the “black,” or neutral unit factor. The equation is as follows:—
A colour matched by
Standard Glasses. Colour Developed.
Red. Yellow. Blue. Neutral Tint. Green. Blue.
1·0 + 3·0 + 9·0 = 1·0 + 2·0 + 6·0
The colour is a blue green, in the proportion of six to two, saddened by one of neutral tint.
A given complex colour of greater brightness than the glass standards, is first dulled by the interception of neutral tint units, until measurable in the manner described above; the intercepting glasses represent the unit value of excess of brightness, and is shown in the equation as light units, for instance—
Standard Glasses. Colour Developed.
Neutral Tint. Yellow. Blue. Light. Green. Yellow.
1·5 + 7·5 + 0·5 = 1·5 + 0·5 + 7·0
The colour is a yellow green in the proportions of 7·0 of yellow, to 0·5 of green, and 1·5 brighter than the standards.
Every daylight colour being thus measurable by a suitable combination of standard glasses, with or without the addition of a Light, or a Neutral Tint factor, it follows that any colour can be described both qualitatively, and quantitatively, in terms of the colour sensations yielded by the standard glasses and their combination. The distinct colour sensations are those, which, by common consent are known as Red, Yellow, Blue, Orange, Green and Violet, and they are yielded by single glasses, or by pairs as already described; all colours therefore fall into the following categories:—
A.—Single colour sensations:—
1. Transmitted by single glass standards:
Red.
Yellow.
Blue.
2. Transmitted by equivalent pairs of standard glasses:
Orange.
Green.
Violet.
B.—Double colour sensations transmitted by unequal pairs of standard glasses.
Red orange, transmitted by unequal units of red and yellow, red preponderating.
Yellow orange, transmitted by unequal units of red and yellow, yellow preponderating.
Yellow green, transmitted by unequal units of yellow and blue, yellow preponderating.
Blue green, transmitted by unequal units of yellow and blue, blue preponderating.
Blue violet, transmitted by unequal units of blue and red, blue preponderating.
Red violet, transmitted by unequal units of blue and red, red preponderating.
C.—Any of the above colours with the addition or subtraction of neutral tint.
Neutral tint itself, is transmitted by a combination of equal units of the standard glasses, thus three units red, yellow and blue, when superposed, transmit three units neutral tint.