Photographic exposure control system and method
First Claim
1. A photographic exposure control system for classifying ambient scene lighting conditions as normal, backlit or forelit and, thereafter, automatically selecting appropriate exposure parameters for the indicated conditions, said system comprising:
- means, including a shutter arrangement, responsive to exposure parameter signals for controlling transmission of image forming light from a scene area to a photosensitive recording medium during an exposure interval;
means, operative during a pre-exposure interval, for emitting ranging signals toward the scene area, separately measuring reflected back portions of the said ranging signals from each of a plurality of selected different scene area portions to determine the distance range of subjects therein, comparing said range measurements, and providing a signal identifying the scene area portion having the nearest subject therein to designate said portion as the subject area;
means, operative during said pre-exposure interval or during an initial portion of the exposure interval, for separately measuring the ambient light intensity in each of the selected different scene area portions and providing corresponding separate light intensity signals for each said portion;
means responsive to said subject area identifying signal and said light intensity signals for comparing the subject area light intensity with the light intensity of non-subject areas and, as a result of the comparison, providing a signal classifying ambient scene lighting conditions as normal, backlit or forelit;
means for storing normal, backlit and forelit exposure parameter signal programs; and
means responsive to said classifying signal for selecting the appropriate one of said programs corresponding to said classifying signal and transmitting said selected program of signals to said means for controlling transmission of image forming scene light to said recording medium.
3 Assignments
0 Petitions
Accused Products
Abstract
A photographic exposure control system automatically classifies ambient scene lighting conditions as normal, backlit or forelit and then selects an exposure parameter signal program that is appropriate for the indicated conditions. The system monitors a plurality of different portions of the scene area with a multi-sensor array that detects both subject range and ambient light intensity. A comparison of range measurements identifies that scene area portion having the nearest subject therein as the subject area. Ambient light intensity measurements of subject and non-subject areas are compared to classify lighting conditions and select a corresponding one of normal, backlit and forelit signal programs which control operation of system components to vary the ratio of ambient to artificial light contribution to exposure for the indicated lighting conditions.
74 Citations
28 Claims
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1. A photographic exposure control system for classifying ambient scene lighting conditions as normal, backlit or forelit and, thereafter, automatically selecting appropriate exposure parameters for the indicated conditions, said system comprising:
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means, including a shutter arrangement, responsive to exposure parameter signals for controlling transmission of image forming light from a scene area to a photosensitive recording medium during an exposure interval; means, operative during a pre-exposure interval, for emitting ranging signals toward the scene area, separately measuring reflected back portions of the said ranging signals from each of a plurality of selected different scene area portions to determine the distance range of subjects therein, comparing said range measurements, and providing a signal identifying the scene area portion having the nearest subject therein to designate said portion as the subject area; means, operative during said pre-exposure interval or during an initial portion of the exposure interval, for separately measuring the ambient light intensity in each of the selected different scene area portions and providing corresponding separate light intensity signals for each said portion; means responsive to said subject area identifying signal and said light intensity signals for comparing the subject area light intensity with the light intensity of non-subject areas and, as a result of the comparison, providing a signal classifying ambient scene lighting conditions as normal, backlit or forelit; means for storing normal, backlit and forelit exposure parameter signal programs; and means responsive to said classifying signal for selecting the appropriate one of said programs corresponding to said classifying signal and transmitting said selected program of signals to said means for controlling transmission of image forming scene light to said recording medium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of classifying ambient scene area lighting conditions as normal, backlit or forelit for photographic purposes, said method comprising the steps of:
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emitting ranging signals towards the scene area; separately measuring reflected back portions of said ranging signals from each of a plurality of selected different scene area portions to determine the distance range of subjects therein; comparing said range measurements to determine which scene area portion has the nearest subject therein; providing a signal identifying the portion having the nearest subject therein to designate that portion as the subject area; separately measuring the ambient light intensity in each of said different scene area portions; utilizing said identifying signal to determine which of said light intensity measurements corresponds to said subject area; comparing said subject area light intensity measurements with a non-subject area light intensity measurement; and providing a signal classifying lighting conditions as normal when the ratio of subject area to non-subject area light intensity is within a predetermined normal range, providing a signal classifying conditions as backlit when the ratio falls within a range that is lower than said normal range, and providing a signal classifying conditions as forelit when the ratio falls within a range that is higher than said normal range. - View Dependent Claims (14, 15, 16, 17, 18)
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19. The method of classifying ambient lighting conditions in a scene area as normal, backlit, or forelit and thereafter selecting appropriate exposure parameters for the indicated conditions utilizing a photographic exposure control system comprising means, including a shutter arrangement, responsive to exposure parameter signals for controlling transmission of image forming light from a scene area to a photosensitive film recording medium during an exposure interval and means for storing normal, backlit and forelit exposure parameter signal programs, said method comprising the steps of:
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emitting ranging signals towards the scene area; separately measuring reflected back portions of said ranging signals from each of a plurality of selected different scene area portions to determine the distance range of subjects therein; comparing said range measurements to determine which scene area portion has the nearest subject therein; providing a signal identifying the portion having the nearest subject therein to designate that portion as the subject area; separately measuring the ambient light intensity in each of said different scene area portions; utilizing said identifying signal to determine which of said light intensity measurements corresponds to said subject area; comparing said subject area light intensity measurement with a non-subject area light intensity measurement; providing a signal classifying lighting conditions as normal when the ratio of subject area to non-subject area light intensity is within a predetermined normal range, providing a signal classifying conditions as backlit when the ratio falls within a range that is lower than said normal range, and providing a signal classifying conditions as forelit when the ratio falls within a range higher than said normal range; selecting the corresponding one of the normal, backlit and forelit exposure parameter signal programs in accordance with the classifying signal provided; and transmitting the selected program to said means for controlling transmission of image forming light to said recording medium. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A photographic exposure control system for classifying ambient scene lighting conditions as being one of a plurality of different predetermined lighting conditions and, thereafter, automatically selecting appropriate exposure parameters for the indicated conditions, said system comprising:
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means, including a shutter arrangement, responsive to a selected exposure program for controlling transmission of image forming light from a scene area to a photosensitive recording medium during an exposure interval; means, operative during a pre-exposure interval or during an initial portion of the exposure interval, for determining the distance range of subjects in each of a plurality of selected different scene area portions, comparing the distance ranges, and providing a signal identifying the scene area portion having the nearest subject of interest therein to designate said portion as the subject area of the scene; means, operative during the pre-exposure interval or during an initial portion of the exposure interval, for separately measuring the ambient light intensity in each of the selected different scene area portions and providing corresponding separate light intensity signals for each said portion; means responsive to said subject area identifying signal and said light intensity signals for comparing the subject area light intensity with the light intensity of non-subject area and, as a result of the comparison, providing a signal classifying ambient scene lighting conditions as a corresponding one of said plurality of different lighting conditions; means for providing exposure programs for each of said plurality of different lighting conditions; and means responsive to said classifying signal for selecting the appropriate one of said exposure programs and for transmitting said selected program to said means for controlling transmission of image forming scene light to said recording medium in accordance therewith. - View Dependent Claims (27, 28)
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Specification