Controlling image signals in an imaging apparatus
First Claim
Patent Images
1. Imaging apparatus comprising:
- means for producing electrical image signals of a given level representing a brightness for each of a number of pixels in a scene;
means for controlling the level of said signals;
digital means for determining if there is a difference between the number of said pixels in a high brightness band and the number thereof in a low brightness band; and
feedback means responsive to said difference for adjusting said level control means at least to reduce said difference.
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Abstract
Thermal imaging apparatus is provided with a comparator and a digital counter for counting the number of pixels in the scene within certain defined brightness bands. Utilizing this data, a microprocessor controls gain, level, gamma correction and integration for noise reduction.
69 Citations
18 Claims
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1. Imaging apparatus comprising:
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means for producing electrical image signals of a given level representing a brightness for each of a number of pixels in a scene; means for controlling the level of said signals; digital means for determining if there is a difference between the number of said pixels in a high brightness band and the number thereof in a low brightness band; and feedback means responsive to said difference for adjusting said level control means at least to reduce said difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. Imaging apparatus comprising means for producing electrical image signals representing a brightness for each of a number of pixels in a scene;
- digital means for calculating a proportion which equals the number of pixels in said scene determined to be within an intermediate brightness band divided by the number of pixels determined to be in said scene and to compare said calculated proportion with a predetermined proportion; and
feedback means for reducing or increasing gain applied to said electrical image signals according to whether said calculated proportion is less or more than said predetermined proportion.
- digital means for calculating a proportion which equals the number of pixels in said scene determined to be within an intermediate brightness band divided by the number of pixels determined to be in said scene and to compare said calculated proportion with a predetermined proportion; and
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17. Imaging apparatus comprising:
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means for producing electrical image signals representing a brightness for each of a number of pixels in a scene; digital means operative to determine the number of said pixels in a first relatively wide intermediate brightness band and in a second relatively narrow intermediate brightness band; gain adjusting means for said electrical image signals; and control means controlling said gain adjusting means in response to said digital means to reduce the gain if there is less than a first predetermined proportion of the total number of pixels within said first band and to increase the gain if there is more than a second predetermined proportion of the total number of pixels in the second band.
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18. Imaging apparatus comprising:
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means for producing electrical image signals representing a brightness for each of a number of pixels in a scene, said signals being produced in a succession of frames; gain adjusting means for adjusting the gain applied to said electrical image signals; digital integration means for noise reduction, said digital integration means being operable to integrate said image signals over a plurality of said frames by adding the signals representing corresponding pixels in each frame of said plurality; and means for increasing and decreasing the number of frames in said plurality with increase and decrease of said gain, whereby when said gain is increased, said number of frames over which said integration occurs is increased and when said gain is decreased, said number of frames over which said integration occurs is decreased.
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Specification