Image input apparatus having addition and subtraction processing
AssigneeCanon Kabushiki Kaisha
InventorsMakoto Hiramatsu, Motohiro Ishikawa
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Abstract
Image data having a high S/N ratio is obtained even when the exposure time is relatively long. To achieve the above object, there is provided an image input apparatus in which an accumulation mode is set with the shutter open, thereby acquiring image data A1. The shutter is then closed, and the accumulation mode is set to acquire subtraction data between the image data and black image data A2. This processing is repeated to acquire image data A1 and subtraction data A2, and these subtraction data are added. These operations A1, A2, and A3 are repeated a predetermined number of times to update addition data, and image processing is performed on the basis of the updated addition data.
Claims10
An image input apparatus comprising:
- image pickup means for converting an optical image from an object into electrical image information and accumulating the electrical image information;
- shielding means for shielding said image pickup means from incidence of the optical image;
- and
- processing means for processing the image information from said image pickup means,
- wherein said processing means comprises:
- first image information acquiring means for acquiring first image information by closing said shielding means before image pickup,
- second image information acquiring means for repetitively acquiring, a first predetermined number of times with said shielding means open, second image information accumulated in said image pickup means within a predetermined period,
- first subtraction processing means for executing a subtraction process between each second image information acquired from said second image information acquiring means and the first image information acquired from said first image information acquiring means,
- first addition means for adding the subtraction results from said first subtraction processing means,
- third image information acquiring means for repetitively acquiring, a second predetermined number of times with said shielding means closed after image pickup, third image information accumulated in said image pickup means within a predetermined period,
- second subtraction processing means for performing a subtraction process between each third image information acquired from said third image information acquiring means and the first image information acquired from said first image infonnation acquiring means,
- second addition means for adding the subtraction results from said second subtraction processing means, and
- adding-up means for adding up said first and second addition means.
An image data processing method comprising:
- an image pickup step of converting an optical image from an object into electrical image information and accumulating the electrical image information in image pickup means;
- a shielding step of shielding said image pickup means from incidence of the optical image by using shielding means;
- and
- a processing step of processing the image information from said image pickup means,
- wherein said processing step comprises:
- a first image information acquisition step of acquiring first image information by closing said shielding means before image pickup,
- a second image information acquisition step of repetitively acquiring, a first predetermined number of times with said shielding means open, second image information accumulated in said image pickup means within a predetermined period,
- a first subtraction processing step of executing a subtraction process between the repetitively acquired second image information and the first image information,
- a first addition step of adding the subtraction results obtained in the first subtraction processing step to calculate a first sum,
- a third image information acquisition step of repetitively acquiring, a second predetermined number of times with said shielding means closed after image pickup, third image information accumulated in said image pickup means within a predetermined period,
- a second subtraction processing step of performing a subtraction process between the repetitively acquired third image information and the first image information,
- a second addition step of adding the subtraction results obtained in the second subtraction processing step to calculate a second sum, and
- an adding-up step of adding up the first and second sums.
Dependencies are inferred from the claim text.