In daily life, we can also feel that when viewing the same item under different light sources or environments, the color of the items presented in our eyes will be more or less biased, because different light sources have different spectral characteristics When the same object is illuminated, different colors appear.
In the case of color management at a printing plant, similar situations can occur. For example, although the quality inspector has carefully compared the colors of the products, when the products are delivered to the customer, they also receive complaints from the customers about the color differences of the products. It may result in a return or customer claim and the company’s reputation will naturally be affected.
To solve this problem effectively, the easiest way is to verify the color of the product under the same light source and under controllable conditions, such as the commonly used fluorescent CIED65 (ie 6500K color temperature), otherwise all the assessment is meaningless. To achieve this, there is no use of the most common standard color light source.
As a customer service person who provides quality inspection instrument manufacturers for printing companies, I contact the Quality Inspection Department of the printing factory all year round. The following discussion will be made on how to carry out standard color matching and the required conditions.
Light source standard
1. Use fluorescent lamp D65
Refined color discrimination in industrial production requires that the illumination source has a real daylight spectral distribution (including ultraviolet radiation and spectral radiation), and the fluorescent lamp D65 approved by the International Commission on Illumination (CIE) can perfectly simulate real sunlight.
2. Light source characteristics
The illumination range of the light source is between 750 and 3200 lux, the color rendering index is >90, and the uniformity is >80%.
3. The background color requirements
Obvious color is a subjective feeling, so comparing colors in different backgrounds can produce different results. Therefore, all background colors are defined as Neutral Grey with a Munsell value of 6-8.
4. The requirements of environmental factors in color discrimination
Try to block all the extraneous light that may be shining on the detector. If the window is in the field of view, it should be equipped with a gray curtain, so the color discrimination in the darkroom is the most ideal.
5. Record the use time of the standard lamp
All standard light sources are acted on by the lamp, and the lamp manufacturer will also specify that its product is operating for a certain period of time and therefore requires an accurate time recorder. Normally these lamps must be replaced after they have been used for some time.
6. Lamp arrangement
There is no specific requirement for the alignment of the lamps, but the arrangement of the lamps must have a uniform light source in the light box and must not be laterally offset in a certain area.
The correct use of standard light sources
1. Observation angle
The above are the facilities that standard light sources must have, but the observation angle will also directly affect the color recognition results. According to international standards, only two observation angles can be used:
a. 0° light source, 45° observation (0°/45°) means that the light source is illuminated on the print at an angle of incidence of 0° (vertical), and the viewer observes the print at an angle of 45°.
b. 45° light source, 0° observation (45°/0°) Use a specific 45° inclined angle table (45°FixedAngleTable) so that the light source illuminates the printed material at an angle of 45°, and the observer observes the angle at 0° (vertical ) Observe the printed matter.
2. Placement of prints
Regardless of which of the above observation methods is used, the printed matter should be placed as far as possible in the middle of the light source to reduce the influence of the external light source. The most important thing is that when it is necessary to compare the colors of two or more items, try not to overlap them, and it is best to discharge them under the light source.
In the case of color management at a printing plant, similar situations can occur. For example, although the quality inspector has carefully compared the colors of the products, when the products are delivered to the customer, they also receive complaints from the customers about the color differences of the products. It may result in a return or customer claim and the company’s reputation will naturally be affected.
To solve this problem effectively, the easiest way is to verify the color of the product under the same light source and under controllable conditions, such as the commonly used fluorescent CIED65 (ie 6500K color temperature), otherwise all the assessment is meaningless. To achieve this, there is no use of the most common standard color light source.
As a customer service person who provides quality inspection instrument manufacturers for printing companies, I contact the Quality Inspection Department of the printing factory all year round. The following discussion will be made on how to carry out standard color matching and the required conditions.
Light source standard
1. Use fluorescent lamp D65
Refined color discrimination in industrial production requires that the illumination source has a real daylight spectral distribution (including ultraviolet radiation and spectral radiation), and the fluorescent lamp D65 approved by the International Commission on Illumination (CIE) can perfectly simulate real sunlight.
2. Light source characteristics
The illumination range of the light source is between 750 and 3200 lux, the color rendering index is >90, and the uniformity is >80%.
3. The background color requirements
Obvious color is a subjective feeling, so comparing colors in different backgrounds can produce different results. Therefore, all background colors are defined as Neutral Grey with a Munsell value of 6-8.
4. The requirements of environmental factors in color discrimination
Try to block all the extraneous light that may be shining on the detector. If the window is in the field of view, it should be equipped with a gray curtain, so the color discrimination in the darkroom is the most ideal.
5. Record the use time of the standard lamp
All standard light sources are acted on by the lamp, and the lamp manufacturer will also specify that its product is operating for a certain period of time and therefore requires an accurate time recorder. Normally these lamps must be replaced after they have been used for some time.
6. Lamp arrangement
There is no specific requirement for the alignment of the lamps, but the arrangement of the lamps must have a uniform light source in the light box and must not be laterally offset in a certain area.
The correct use of standard light sources
1. Observation angle
The above are the facilities that standard light sources must have, but the observation angle will also directly affect the color recognition results. According to international standards, only two observation angles can be used:
a. 0° light source, 45° observation (0°/45°) means that the light source is illuminated on the print at an angle of incidence of 0° (vertical), and the viewer observes the print at an angle of 45°.
b. 45° light source, 0° observation (45°/0°) Use a specific 45° inclined angle table (45°FixedAngleTable) so that the light source illuminates the printed material at an angle of 45°, and the observer observes the angle at 0° (vertical ) Observe the printed matter.
2. Placement of prints
Regardless of which of the above observation methods is used, the printed matter should be placed as far as possible in the middle of the light source to reduce the influence of the external light source. The most important thing is that when it is necessary to compare the colors of two or more items, try not to overlap them, and it is best to discharge them under the light source.
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