This standard specifies two sets of standard Color Matching functions for use in Colorimetry. The first set is the CIE 1931 Standard Colorimetric Observer, suitable for observers with viewing angles of approximately 1 ° to 4 °, representing Color Matching characteristics under normal color vision. The second set is the CIE 1964 Standard Colorimetric Observer, suitable for observers with viewing angles greater than 4 °, suitable for Color Matching at high luminance levels. These functions are used to calculate the tristimulus values of Color to ensure that Color data obtained at different times and locations can be compared consistently. The standard is designed to provide an accurate Color Matching benchmark to support a variety of visual assessments and Colorimetric tests.