Television – Camera – system and detail – Optics
Reexamination Certificate
1998-03-11
2001-01-23
Garber, Wendy (Department: 2712)
Television
Camera, system and detail
Optics
C348S333040, C348S333110
Reexamination Certificate
active
06177958
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to electronic imaging devices and more particularly to a system and method for the automatic capture of salient still images by an electronic imaging device.
2. Description of the Background Art
One of the advantages of digital cameras is their ability to capture images of objects for later manipulation by computer graphics programs. However, digital cameras have a limited dynamic range of exposure sensitivity.
In conventional photography, photographic films capture a wide range of light exposure levels. These films capture detail in both shadow or dark areas and light or bright areas with a single camera exposure of the film. Digital cameras, however, have a much narrower dynamic range due to the use of a charged-coupled device (CCD.) Thus, unlike conventional photographic exposure that captures shadow detail without washing-out image highlights in a high contrast scene, a digital camera will lose a substantial amount of detail in either the darkest areas of the image, or in the brightest areas, or both.
Conventionally, photographers employ a manual method of camera operation known as “bracketing” of exposure setting to record images on photographic film. A photographer takes a first picture at a first exposure setting by adjusting the f-stop on the camera lens and/or the shutter speed dial on the camera body. The photographer then takes a second picture at a second exposure setting for a different light level by changing the f-stop and/or shutter speed. The first exposure setting admits more light for the first picture while the second exposure setting admits less light for the second picture, or vice versa. Thus, the image is said to be “bracketed” between these two settings.
One of the bracketed images on the developed photographic film reveals more detail in the darker areas of the picture while the other bracketed image reveals more detail in the lighter areas. The photographer chooses which of the bracketed images appears best, but conventional photographic methods do not provide any method of combining the images at time of capture to produce the best detail of each. The prior art, however, provides for methods of digitizing the images after the film is developed. Once the bracketed exposures are digitized, a variety of post-production editing programs are available to combine the images.
Automatic cameras allow the photographer to “autobracket” a given image. The photographer sets the range of the bracketing feature (the X factor.) The camera's autobracketing feature then captures a series of images, typically one at the auto metered point, plus one on either side of the metered exposure (usually at +X and −X.) The photographer may then choose which of the images captured by the autobracketing feature to keep, based on the resulting images after processing.
What is required is a method to automatically calculate the need for bracketing, and to calculate the bracketed exposures to capture the image in its full detail. In addition, what is required is a method to put the image data in a form that the computer software may automatically recognize and change into a single, distortion-free image.
SUMMARY OF THE INVENTION
The present invention relates to an improvement in digital imaging devices, including digital cameras, and comprises a system and method for the automatic capture of salient still images.
A user initially sets an exposure control coupled to the electronic imaging device for selecting a salient still capture mode. During operation, a camera control sub-system detects a high contrast image. The camera control sub-system notifies a control application that the camera control sub-system has detected the high contrast image. The control application responsively notifies the user that a high contrast image has been detected. Then, the imaging device determines which of two salient still capture modes has been selected: (1) salient still capture automatic mode, or (2) salient still capture manual mode.
During salient still capture automatic mode, the present invention automatically captures a plurality of salient still images. In one embodiment, the auto-exposure (AE) mechanism of the camera determines an average exposure value of the high contrast image. The invention then captures two images based upon the auto-exposure value. The camera exposes the first salient still image to capture the dark image data of the high contrast image and exposes the second salient still image to capture the bright image data of the high contrast image.
A capture manager automatically adjusts the exposure setting for the first salient image by setting the exposure a pre-set value below (−X) the auto-exposure average value to capture the dark image. The capture manager then automatically adjusts the exposure setting for the second salient image by setting the exposure a pre-set value above (+X) the autoexposure average value to capture the bright image. These exposures are hopefully far enough apart to capture the dark and bright image data while maintaining an optimum image overlap in order to capture adequate image detail. In the preferred embodiment, the +X and −X values are loaded during initial camera set-up.
In a second embodiment, the AE mechanism determines an auto-exposure dark value and an auto-exposure bright value of the high contrast image. The AE mechanism then subtracts the auto-exposure dark value from the auto-exposure bright value, divides the result by two, and uses this mean value as the AE average. The AE mechanism then determines the number of images to capture based upon the difference between the auto-exposure dark value and the auto-exposure bright value. If the difference exceeds the dynamic range of the two captures with overlap, then three or more images are required.
In either embodiment, the captured images are tagged as salient images and grouped together. Preferably, the grouped files are stored in salient image folders either during or after capture process is completed. The two salient images are later combined into a single digital image by software routines. Alternatively, the images are combined during initial processing and stored as a single image.
During salient still capture manual mode, the present invention offers the user a choice of whether or not to capture two salient still images. If the user selects to capture the two salient still images, the invention proceeds as in automatic mode. On the other hand, if the user does not enable the dual capture, then only a single image will be captured.
Thus, the present invention provides a method to automatically calculate the need for bracketing, and to calculate the bracketed exposures to capture a high contrast image in its full detail. In addition, the present invention provides a method to put the image data in a form that the computer software may automatically recognize and change into a single, distortion-free image.
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Flashpoint Technology, Inc.
Garber Wendy
Moe Aung S.
Sawyer Law Group LLP
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