Automatic Hot Pixel Recognition and Correction for Digital Cameras and Other Pixel Detectors

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This invention provides a method and system for automatically detecting and correcting 'hot pixels' in digital cameras or other pixel-based sensors. Hot pixels are sensor defects that appear as bright spots on images, irrespective of actual scene brightness. The system periodically takes a dark (black frame) exposure to locate and record the positions of these hot pixels using a statistical analysis of pixel brightness values. During normal image capture, these detected hot pixels are corrected by replacing their values with those from surrounding pixels, automatically removing such blemishes from the final image.

Use CasesContent extracted from patent full text and abstract with AI.

• Consumer digital cameras and smartphones to enhance image quality by removing sensor blemishes.
• Professional photography equipment, especially for long exposures or astrophotography where hot pixels are more visible.
• Video cameras and live streaming devices for real-time hot pixel correction.
• Industrial machine vision cameras for defect-free image processing.
• Medical imaging systems using digital sensors (e.g., radiography) to ensure clear diagnostic images.
• Scientific imaging instruments where pixel-level defects can affect data integrity.
• Security and surveillance cameras that must provide reliable and clear imagery regardless of sensor degradation.

BenefitsContent extracted from patent full text and abstract with AI.

• Significantly improves final image and video quality by automatically removing bright dot defects (hot pixels).
• Reduces the need for expensive hardware repairs or sensor replacements due to hot pixel accumulation over time.
• Ensures consistent image quality throughout the device's lifespan, even as new hot pixels develop from factors like cosmic rays or wear.
• Performs hot pixel detection and correction efficiently, requiring minimal computational resources; suitable for use even in low-cost cameras or mobile devices.
• Operates under real-world (field) conditions and adapts automatically to changing sensor states and environments.
• Robust against both individual and clustered hot pixels, ensuring comprehensive correction.
• Correction process is largely invisible to the user and can run automatically without user intervention, but can be manually triggered as needed (such as after sensor cleaning).

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Patent Abstract

A method and system for automatic bad pixel recognition and correction in image pixel sensors is provided. The process of identifying hot pixels requires few resources. The required resources can be met even by today's low price consumer point-and-shoot cameras and camera's built into phones. Hot pixels are identified via a complementary cumulative distribution function (CDF) for the raw pixel digital numbers (DN) of a black frame. This black frame hot pixel recording step is done once in a while like a sensor cleaning. Simple analysis of the tail of the CDF allow to define a sharply discriminating threshold for hot pixels. Subsequent analysis of the black frame for pixels with above threshold DN yields a table or map with hot pixel positions. In normal imaging mode, the table is used to replace the hot pixel DN by a value from a pixel nearby, thereby repairing the bright pixel blemish which is present in the unprocessed image data.