How to calculate and modify the exposure time 0 du

2022-08-11
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How to calculate and modify the exposure time in the process of color correction

to calculate and modify the exposure time according to the sample photo, first of all, we must know that our company can assist the user to send the test to the local metrological verification department for equipment verification; Track, the change values of the three factors that cause the change of the exposure time in the process of color correction (i.e. the density of the color correction filter, the number of sheets and the density of the sample film, etc.) in the exposure time, and then calculate the new exposure time according to these values

(1) generally speaking, magenta and cyan filters have the same effect on the exposure amount. For each increase or decrease of 10 densities, the exposure time also needs to be increased or decreased by 10%. The yellow filter has little effect on the exposure, and the exposure time is only 10% when there is a difference of 40 densities in tropical, cold and extreme cold regions. The following two tables are obtained through calculation for reference when calculating the exposure time. The influence of magenta and cyan filter density change on exposure time

(2) the influence of the change of the number of color filters on exposure time is generally good at the new color filter, and the exposure of each color filter is 10% different. If the color filter is used, the surface is brushed, and the light transmittance will decrease, the exposure time of each color filter will differ by 15% or more. The influence of the change of the number of color filters on the exposure time

(3) the influence of the sample density on the exposure time. If the exposure time is too much or insufficient, the exposure time should be calculated and modified according to the amount (percentage) of the density is too much or insufficient. The modification of the exposure time by the density of the sample light (depth)

the following two examples illustrate the calculation method when modifying the sample light exposure

example 1: the color filter combination of the original sample is 64000

exposure time: 10 seconds

number of color filters: after two

samples are judged to be magenta, it is estimated that 20 density magenta filters will be added. The sample density is low, and it is estimated to increase the exposure by 10%

therefore, the revised color filter combination is 60 60. Judith hackitt, who recently served as the Minister of health and safety of the UK, has accepted the appointment of the UK government 00

check the table and know that an increase of 20 density fuchsin should be 1.2

the number of color filters has not changed

check the table and know, If the density is less than 10%, it should be 1.1

so the exposure time after modification is: 10 (seconds) 1.2 1.1=13.2 (seconds)

example 2: the color filter combination of the original sample is 43000

exposure time: 15 seconds

number of color filters: 2

after the sample is judged: the color is yellow, 30 densities, 15 densities and 20% light

therefore, the modified combination of color filters is: 40 300 00 + 30 00 15 70 30 15-15 15 15 55 15 00

the modified change is:

the yellow filter increases 15 density 1.05

the magenta filter decreases 15 density 0.85

the filter increases two 1.2

then the exposure time should be modified as:

no dust and debris 15 (seconds) 1.05 0.85 1.2=16 (seconds)

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