the value of the color is represented by the international used color space such as lab, lch, rgb, xyz, yxy,etc. lab is the most commonly used.
cie1976 l*a*b* color space is mainly used for paint, building material ,coating and other other surface color industries. it is also called cielab.l * is the brightness coordinate, which characterizes the brightness of the color.a * b * is the color coordinates, which characterizes the color tone and saturation. please refer to figure.
l represents brightness. 0-100 represents from black to white.
a represents red to green.positive values indicate red and negative values for green.
b represents yellow to green.positive values indicate yellow and negative values for blue.
for example, if the products’ color value is l:22.75,a:22.58,b:13.83.
its represents white is 22.75. red is 22.58, and yellow 13.83.
during the measurement, the first measurement is for target, the second measurement is for getting delta e value which is also called color difference value. the difference is the value of the measured product minus the sample value, the brightness difference 鈻矻, red and green difference 鈻矨 and yellow and blue difference 鈻矪.
the formula is:
鈻矻 = l sample-l standard (brightness difference)
鈻砤 = a sample-a standard (red / green difference)
鈻砨 = b sample-b standard (yellow / blue difference)
鈻矻 too much white, 鈻矻- too much black
鈻砤 too much red, 鈻砤- too much green
鈻砨 too much yellow, 鈻砨- too much blue
鈻矻 *, 鈻砤 *, 鈻矪 * is the difference of brightness l * and chromaticity value a * and b * between the target and sample.
鈻矱 represents color difference value, the calculation method and the brightness difference 鈻矻, red and green difference 鈻矨, yellow and blue difference 鈻矪 have a relationship.
the formula is:
鈻矱=[(鈻矻) (鈻砤) (鈻砨)]1/2
customers are mainly based on the 鈻矱, brightness difference 鈻矻, red and green difference 鈻矨 and yellow and blue difference 鈻矪 for color matching and adjusting.
鈻矻 is positive, indicates that the measured product is brighter than the sample, negative indicates the measured product is darker than the sample;
鈻矨 is a positive value, indicates the measured product is much more red than the sample, negative value indicates that the measured product is much more green than the sample;
鈻矪 is a positive value, indicates the measured product is much more yellow than the sample, negative value indicates that the measured product is much more blue than the sample;
lch color space, l is brightness, c is chroma, h is hue. brightness, chroma and hue are the three basic properties of color.
rgb color space, r is red, g is green, b is blue. this color space is most commonly used in the printing industry.
xyz color space, xyz value analysis the color according to the object surface reflection characteristics and degree.