Testing requirements and data usage of offset product quality (on)
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First, product quality testing conditions
1. The ambient color around the observation surface: N6-N8, C (0.3. If the wall and the ground around the observation surface do not meet the above requirements, use the baffle that meets the above requirements to enclose the sample. Or use environmental reflection Light, the illuminance produced on the viewing surface is less than 100 LUX.
The background when observing reflection should be N5-N7, C<0.3; for those with higher color matching requirements, C<0.2.
2. The inspection environment is dust-proof and tidy.
3. Operating temperature requirements
The temperature is 23 ° C ± 5 ° C relative humidity is 60 + 15 (-10)%
4. Lighting conditions
1 observation of transmission samples
The light source is a simulated body of CIE standard illuminant D50 (typical 昼 with a correlated color temperature of 6504K, X=0.3457, Y=0.3586 on CIE1931), and the outline of the light source or the sudden change in brightness should not be seen on the observation surface. The uniformity of brightness is ≥80%, and the color rendering index of the light source is Pa≥90.
2 observation of reflective samples
The light source is a simulated body of CIE standard illuminant D65 (typical calender of correlated color temperature 6504K, X=0.3127, Y=0.3291 on CIE1931). There should be no illuminance mutation on the observation surface. The uniformity of illuminance is ≥80%, and the color rendering index of the light source is Ra≥90.
5. The observer must be a non-color blind and non-colored normal color vision observer.
Second, the observation method
1. The transmissive sample should be illuminated by ineffective diffuse light from the back, observed perpendicular to the surface of the sample. When viewing, try to place the sample in the middle of the illuminated surface so that at least three sides have a 50mm wide illuminated boundary. When the sum of the areas of the observed transmission samples is less than 70 mm × 70 mm, the width of the illuminated boundary should be appropriately reduced so that the boundary area does not exceed 4 times the sample area, and many portions are covered with a gray opaque light-blocking material.
2. When observing the reflected sample, the light source is perpendicular to the surface of the sample, and the observation angle is at an angle of 45° to the normal of the sample surface. For the 0°-45° illumination observation condition, as shown in Fig. 1. As an alternative observation condition, it is also possible to illuminate with a light source at an angle of 45° to the normal to the surface of the sample, and to observe the surface of the vertical sample, corresponding to an illumination observation condition of 45°-0°. See Figure 2.
Third, the use of measurement and control strips
1, the principle of measurement and control
1 The increase in the area of the dot is proportional to the total length of the edge of the dot.
2 Using the geometrical area equal to the yin and yang to measure the transfer change of the dot.
3 When the pattern changes, the angle changes significantly at the angle of the arc and acts as an amplification.
4 Use horizontal or unequal width fold lines to measure horizontal and vertical azimuth changes.
5 Use the isometric concentric circle to measure the change of any orientation.
2, the conditions of use
The conditions for using the test strip should be consistent with the conditions for printing, proofing and printing.
3, how to use
A long strip should be placed at the end of the sheet in parallel with the axis of the press cylinder to control the uniformity of image inking.
4, printing common control strips
1GATF star: used to measure dot enlargement, slip, and ghost.
2GATF signal strip: used to measure dot enlargement and deformation.
3Brunner signal strip: used for density measurement, dot gain, dot deformation.
4 high-profile dot detection chart: used to observe the high-resolution dot reproduction.
CY/T5-1999 fine prints are reproduced in 2%-4% dot area, and the general prints are reproduced in 3%-5% dot area.
5GATF color signal strip: used to determine dot gain, deformation, density, gray balance.