| CPC H04N 23/73 (2023.01) [G03B 7/093 (2013.01); H04N 23/71 (2023.01); H04N 23/74 (2023.01)] | 16 Claims |
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1. A method for recording a sequence of images by means of a digital motion picture camera comprising an image sensor for generating electrical signals in dependence of an exposure of the image sensor, wherein at least two exposure changing devices are provided which are configured to influence the exposure of the image sensor by a setting of a respective operation parameter and which are selected from a group of exposure changing devices comprising at least one image recording rate setting device, a diaphragm aperture setting device, an electronic shutter of the image sensor, a mechanical shutter, an adjustable neutral density filter and at least one controllable illumination device for illuminating a subject which can be captured by the motion picture camera,
wherein one of the exposure changing devices is provided as a variation device or can be selected as such, and at least one further exposure changing device, different to the variation device, is provided as an at least one compensation device or can be selected as such,
wherein at least one control device is provided, which is configured to receive a setting value of the operation parameter of the variation device and to output a respective adjustment value to the at least one compensation device,
the method comprising the following steps which are performed in a variation operation during a recording of a sequence of images:
influencing the exposure of the image sensor by changing the setting value of the operation parameter of the variation device;
receiving the changed setting value;
determining a respective adjustment value of the operation parameter of the at least one compensation device and outputting the respective adjustment value from the control device to the at least one compensation device in dependence of the received changed setting value of the operation parameter of the variation device, wherein the respective adjustment value is selected such that the influence on the exposure of the image sensor caused by the change to the setting value is at least substantially compensated by a change to the respective adjustment value; and
operating the at least one compensation device in accordance with the outputted respective adjustment value,
wherein the respective adjustment value of the operation parameter of the at least one compensation device is determined in dependence of the changed setting value of the operation parameter of the variation device based on a predetermined relationship between different setting values of the operation parameter of the variation device and associated adjustment values,
wherein in a calibration operation, which is performed prior to the variation operation, the predetermined relationship between the different setting values of the operation parameter of the variation device and the associated adjustment values is determined and stored in a storage device connected to or is connectable to the control device,
wherein determining the predetermined relationship comprises:
for a constant intensity of light entering the motion picture camera, setting in succession the different setting values of the operation parameter of the variation device and simultaneously thereto, determining respective associated brightness values representing the exposure of the image sensor based on image signals from the image sensor, wherein a characteristic curve of variation is determined on the basis of the different setting values and the associated brightness values; and
determining computationally or experimentally at least one characteristic curve of compensation which, for a respective compensation device, associates a desired change in a brightness value captured by the image sensor with a necessary change to the adjustment value of this compensation device,
wherein, in the variation operation, the respective adjustment value of the operation parameter of the at least one compensation device is determined based on the characteristic curve of variation and the at least one characteristic curve of compensation.
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