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GB/T 5702-2003 PDF in English


GB/T 5702-2003 (GB/T5702-2003, GBT 5702-2003, GBT5702-2003)
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GB/T 5702-2003: PDF in English (GBT 5702-2003)

GB/T 5702-2003
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 17.180.10
A 25
Replacing GB/T 5702-1985
Methods of Measuring the Colour of Light Sources
ISSUED ON: JANUARY 10, 2003
IMPLEMENTED ON: JUNE 01, 2003
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC
Replaced
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Evaluation Methods ... 4
4 Colour Rendering Index ... 9
Methods of Measuring the Colour of Light Sources
1 Scope
This Standard specifies a method for quantitatively evaluating the colour rendering of
a light source based on the total colour shift of the test colour sample under the
illumination of the reference light source and the light source to be measured.
This Standard is applicable to the evaluation of colour rendering of artificial lighting
sources, such as incandescent lamps, tungsten halogen lamps, various gas discharge
lamps (fluorescent lamps, high pressure sodium lamps, metal halide lamps, xenon
lamps, etc.), artificial daylight, etc.; except for the light source with dominant
monochromatic radiation, such as low-pressure sodium lamps.
2 Normative References
The provisions in following documents become the provisions of this Standard through
reference in this Standard. For dated references, the subsequent amendments
(excluding corrigendum) or revisions do not apply to this Standard, however, parties
who reach an agreement based on this Standard are encouraged to study if the latest
versions of these documents are applicable. For undated references, the latest edition
of the referenced document applies.
GB/T 3977 Specification of Colours
3 Evaluation Methods
3.1 Selection of reference light source
When evaluating the colour rendering of a light source, a reference light source shall
be selected, and the spectral power distribution of the reference light source shall be
defined by a mathematical formula.
When the correlated colour temperature of the light source to be measured is no higher
than 5000K, the Planck radiator shall be used as the reference light source, and the
Planck formula shall be used to calculate its spectral power distribution, see Formula
(1).
After the chromaticity coordinates of the light source to be measured are obtained, the
colour temperature of the light source to be measured shall be determined by the
chromaticity diagram or calculation method; and the spectral power distribution of the
reference light source shall be calculated by Formulas (1) or (2) ~ (7).
3.2 Tolerance of reference light source
The colour temperature of the reference light source shall be the same or close to that
of the light source to be measured.
The chromaticity difference Δc between the reference light source and the light source
to be measured shall be less than 5.4×10-3 (equivalent to 15MK-1). The value of Δc is
calculated by Formula (8),
Where:
uk, vk – uv coordinate values of the light source to be measured;
ur, vr – uv coordinate values of the reference light source.
3.3 Colour sample for inspection
Select 8 colour samples as a group (i = 1, ..., 8) as the colour samples for inspection
to evaluate the general colour rendering index; and their spectral radiance coefficients
are shown in Table 2.
Select 7 colour samples (i =9, ..., 15) as the colour samples for inspection to evaluate
the special colour rendering index. They respectively represent dark red, dark yellow,
dark green, dark blue, white skin, leaf green, Chinese female skin. The spectral
radiance coefficient is shown in Table 3.
3.4 Determination of the CIE 1931 XYZ tristimulus value of colour sample for
inspection
The relative spectral power distribution of the light source to be measured must be
u’k,i, v’k,i - the uv coordinate value of the ith colour sample for inspection under the
illumination of the light source to be measured after correction of the adaptive colour
shift;
c, d – correction value of adaptive colour shift, which shall be calculated by Formulas
(15) and (16);
r – subscript of the reference light source;
k – subscript of the light source to be measured;
i – subscript of the No. of colour sample for inspection.
3.7 Convert u, v, Y into U*, V*, W* uniform colour space coordinate values
Use the Formulas (17), (18) and (19) to convert u, v, Y into U*, V*, W*.
Where:
U*, V*, W* - U*, V*, W* uniform colour space coordinate values
Y – CIE 1931 XYZ tristimulus value Y of colour sample for inspection;
u, v – uv coordinate values of colour sample for inspection;
u0, v0 – uv coordinate values of light source for illumination.
3.8 Calculation of colour difference
Use Formula (20) to calculate the colour difference ΔEi of the ith colour sample for
inspection under the illumination of light source to be measured and reference light
source.
......
 
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