Dark-frame subtraction

About: Dark-frame subtraction is a research topic. Over the lifetime, 1216 publications have been published within this topic receiving 20763 citations.

Design and Development of an Improved Adaptive Median Filtering Method for Impulse Noise Detection

Abstract: An Impulse noise detection and removal with adaptive filtering approach is proposed to restore images corrupted by salt & pepper noise. The proposed algorithm works well for suppressing impulse noise with noise density from 5 to 60% while preserving image details. The difference of current central pixel with median of local neighborhood pixels is used to classify the central pixel as noisy or noise-free. The noise is attenuated by estimating the values of the noisy pixels with a switching based median filter applied exclusively to those neighborhood pixels not labeled as noisy. The size of filtering window is adaptive in nature, and it depends on the number of noise-free pixels in current filtering window. Simulation results indicate that this filter is better able to preserve 2-D edge structures of the image and delivers better performance with less computational complexity as compared to other denoising algorithms existing in literature.

Noise filtering in solar speckle masking reconstructions

Abstract: A new method of obtaining a sensitive noise filter for solar speckle masking reconstructions is presented below. This filter separates the true image information from noise most reliably. Its efficiency is demonstrated by some representative examples considering observed and artificial image data which were generated in a computer. The latter set of data also suffered realistic degradations by the influence of seeing and noise taken from suitable observations.

Method and apparatus for dark frame cancellation for CMOS sensor-based tethered video peripherals

Abstract: Elimination of dark fixed pattern noise (DFPN) for tethered CMOS sensor-based digital video cameras is supported by supplying and maintaining a host-based dark image cache. Since the camera is tethered to a host computer system such as a PC, it takes advantage of the storage and processing capabilities of the host to manage the cache. By using a dark image cache for updating of the currently applicable dark image for DFPN cancellation processing, operation of the camera shutter for acquiring dark images is dramatically reduced, thereby using less system resources such as power, and increasing the MTBF of the electromechanical devices such as the camera shutter and associated controls. Dark images are obtained at different integration, gain, and temperature operating characteristics of the camera and stored in the cache. The cached dark images are referenced on the host according to a fixed, predetermined dark column of data in video frames generated by the CMOS sensor image array of the camera. The dark column data represents a portion of the CMOS sensor image array which is permanently and totally shadowed for use during DFPN cancellation processing.

Dark frame subtraction

Abstract: A method of adjusting a portion of a dark frame in accordance with compensation values related to dark reference pixels of a picture frame to obtain an adjusted dark frame portion, and then subtracting the adjusted dark frame portion from a corresponding picture frame portion. The technique may be used to improve the accuracy of image sensors such as those used in digital cameras or video conferencing cameras by compensating for dark current noise. The technique may be applied to both CMOS image sensors and, in general, to any image sensors requiring dark frame subtraction. The techniques may also be used in conjunction with calibration of image sensors and imaging systems.