\u672c\u6807\u51c6\u89c4\u5b9a\u4e86\u5ba4\u5185\u5f71\u9662\u548c\u9274\u5b9a\u653e\u6620\u5ba4\u4ee524\u683c/s\u7247\u901f\u653e\u662070mm\u300135mm\u548c16mm\u7535\u5f71\u62f7\u8d1d\u7684\u94f6\u5e55\u4eae\u5ea6\u548c\u8272\u5ea6\u3002\u672c\u6807\u51c6\u9002\u7528\u4e8e\u5ba4\u5185\u5f71\u9662\u3001\u9274\u5b9a\u653e\u6620\u5ba4\u4ee5\u53ca\u5176\u4ed6\u653e\u6620\u573a\u6240\u3002\u6ce8\uff1a\u5728\u672c\u6807\u51c6\u4e2d\uff0c\u201c\u94f6\u5e55\u201d\u4e00\u8bcd\u662f\u6307\u4e0e\u6240\u91c7\u7528\u7684\u753b\u5e45\u89c4\u683c\u53ca\u653e\u6620\u7cfb\u7edf\u76f8\u9002\u5e94\u7684\u653e\u6620\u753b\u9762\u533a\u57df\u3002 GB/T 4645-1994 \u5ba4\u5185\u5f71\u9662\u548c\u9274\u5b9a\u653e\u6620\u5ba4\u7684\u94f6\u5e55\u4eae\u5ea6 GB/T4645-1994 \u6807\u51c6\u4e0b\u8f7d\u89e3\u538b\u5bc6\u7801\uff1awww.bzxz.net
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National Standard of the People's Republic of China
Screen luminance for the projection or motion-picture prints in indoor theatres and review rooms This standard is equivalent to IS02910-1990 "Screen luminance for the projection or motion-picture prints in indoor theatres and review rooms". 1 Subject content and scope of application
GB/T4645---94
Replaces GB292582
GB4645-84
This standard specifies the screen luminance and chromaticity of 70mm, 35mm and 16mm film prints in indoor theatres and review rooms at a film speed of 21 frames/s.
This standard is applicable to indoor theatres, review rooms and other projection venues. Note: In this standard, "screen\.room" refers to the projection picture area that is compatible with the adopted frame specifications and projection system. 2 Reference standards
JJG211 Luminance meter verification procedureswww.bzxz.net
3 Brightness measurement
3.1 Measurement conditions
The projector should be in 24-frame/normal working state. No film should be hung in front of the film window. 3.2 Measuring instrument
The receiving angle of the meter used for measurement should not be greater than 2° (recommended value is 1.5). The brightness meter should comply with the relevant provisions of JJG211. 3.3 Position of indoor theater spot measuring instrument
When measuring in an indoor theater, the brightness meter should be placed in the center of the main seating area of ​​the auditorium, about 1m above the ground. In order to make each seating area obtain a satisfactory viewing effect as much as possible, two points should be taken as the brightness meter measurement position on the audience cross line with a distance of 2/3 of the distance from the screen to the last row of seats. These two points are symmetrical to the longitudinal axis of the auditorium, separated by 2/3 of the width of the auditorium, and about 1m above the ground.
3.4 Position of measuring instrument in the appraisal projection room
When measuring in the appraisal projection room, the brightness meter should be placed on the film review position on the longitudinal axis of the seating area, about 1m above the ground. 4 Center of screen Brightness
4.1 When showing 70mm, 35mm and 16mm films in indoor theaters, the brightness of the center of the screen should be 50±15cd/m (see Appendix A). 4.2 When showing 70mm, 35mm and 16mm films in the appraisal projection room, the brightness of the center of the screen should be 50±7cd/m5 Screen brightness distribution
The brightness distribution of the entire screen should be as uniform as possible, and the screen should be basically symmetrical relative to the center of the screen. Measure the brightness of the two edge points on the horizontal center line of the screen at the positions specified in Articles 3.3 and 3.4. The distance between these two points and the edge of the adjacent side screen is 10% of the screen width. The brightness should not be less than 30% of the brightness of the center of the screen and not higher than 85%. The recommended value is 7556, and the brightness difference between these two points is required not to exceed 10% of the center brightness. In order to obtain uniform screen brightness in each seating area, the National Technical Supervision Bureau approved it on December 28, 1994 and implemented it on August 1, 1995. GB/T 4645-94
Select multiple positions for measurement. When using a gain-type screen, pay more attention to measuring at the side seats and balcony seats in the auditorium. 6 Spectral distribution
The correlated color temperature of the screen reflected light should be 5400 ± 400K. 7 Adjustment of multiple projectors
7.1 Brightness matching of multiple projectors with different frames Use multiple projectors to continuously project movies with the same frame size. The difference in brightness between the center of the screen should not exceed 7d/m. 7.2 Brightness matching of multiple projectors with different frames Use multiple projectors to continuously project movies with the same frame size. When multiple projectors are used to show movies with different frame sizes in sequence, the difference in the color temperature of the screen center should not exceed 14cd/m. 7.3 Color temperature matching
When multiple projectors are used to show movies in sequence, the difference in the color temperature of the screen reflected light should not exceed 400K. When a 16mm film is shown with a light source with a color temperature of 3500K or lower, the difference in the color temperature of the screen reflected light should not exceed 7% of the color temperature of the light source. 8.1 Interference light such as stray light or glare on the screen should be reduced as much as possible. The estimated interference light on the screen in the projection room should not exceed 1% of the brightness of the center of the screen, and the estimated interference light on the screen in the indoor theater should not exceed 1.0% of the brightness of the center of the screen. 8.2 The lighting at the screening position should be strictly shielded, and the brightness should not exceed 3.5cd/m. GB/T 4645~-94
Appendix A
Allowable range of screen height
(reference)
The determination of the allowable range of indoor cinema screen brightness is based on practical experience and constraints. The standard brightness of the screen in the screening room for reviewing various films is determined to be 50cd/m. In order to reproduce the screen picture quality during the screening, the standard brightness of the cinema screen should also be set at 50cd/m. The lower limit of the brightness is determined to be 35cd/m to ensure that there is enough brightness to reproduce the color and details of the picture, especially the darker scenes; the upper limit of the brightness is determined to be 65cd/m2, which is the highest critical brightness value to ensure that the audience does not feel the flicker. (Assuming that the projector shading frequency is 48cd/s)
For non-cinema screening venues, portable projection equipment, especially 16mm projectors, are used, and their luminous flux is limited. The lower limit of the brightness can be determined to be 25cd/m2.
Additional notes:
This standard was proposed by the Ministry of Radio, Film and Television of the People's Republic of China. This standard is under the jurisdiction of the China Film Science and Technology Research Institute of the Ministry of Radio, Film and Television. This standard was drafted by the China Film Science and Technology Research Institute of the Ministry of Radio, Film and Television.
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