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.

Diagnosis and repair of random noise in the sensor's chris-proba

Abstract: . The CHRIS sensor on the PROBA-1 satellite has imaged as push-broom way, 18 meter spatial resolution and 18 bands (1.25–11 nm) spectral resolution from earth since 2001. After 13 years of the life of the sensor because of many reasons including the influence of solar radiation and magnetic fields of Earth and Sun, behaviour of the response function of the detector exit from calibration mode and performance of some CCDs has failed. This has caused some image information in some bands have been deleted or invalid. In some images, some dark streaks or light bands in different locations need to be created to identify and correct. In this paper all type of noise which likely impact on sensor data by CHRIS from record and transmission identified, calculated and formulated and method is presented through modifying. To do this we use the In-fight and On-ground measurements parameters. Otherwise creation of noise in images is divided into horizontal and vertical noise. Due to the random noise is created in different bands and different locations, those images in which noise is observed is used. In this paper, techniques to identify and correct the dark or pale stripe detail of the images are created. Finally, the noisy images were compared before and after the reform and effective algorithms to detect and correct errors were demonstrated.

Novel rotation algorithm for phase unwrapping to solve problems of holes and noise (AFPA)

Abstract: In this study, the novel rotation algorithm is proposed for the phase unwrapping algorithm The main advantage of proposed algorithm is that it can simultaneously resolve the shifting error, holes, two types of noise (ie the residual noise and noise at height discontinuities) By contrast, the common phase unwrapping algorithms which operate phase shifting by 2π, can only filter two types of noise Unfortunately, these common algorithms can not resolve the problems of the shifting error and holes Therefore, compared to these common algorithms, the proposed rotation algorithm is more effective and useful for resolving the problems of holes and noise

Effects of pixel noise and stimulus structure on visual detection performance

Abstract: This thesis consisted of two major parts, one determining the masking characteristics of pixel noise and the other investigating the properties of the detection filter employed by the visual system. The theoretical cut-off frequency of white pixel noise can be defined from the size of the noise pixel. The empirical cut-off frequency, i.e. the largest size of noise pixels that mimics the effect of white noise in detection, was determined by measuring contrast energy thresholds for grating stimuli in the presence of spatial noise consisting of noise pixels of various sizes and shapes. The critical i.e. minimum number of noise pixels per grating cycle needed to mimic the effect of white noise in detection was found to decrease with the bandwidth of the stimulus. The shape of the noise pixels did not have any effect on the whiteness of pixel noise as long as there was at least the minimum number of noise pixels in all spatial dimensions. Furthermore, the masking power of white pixel noise is best described when the spectral density is calculated by taking into account all the dimensions of noise pixels, i.e. width, height, and duration, even when there is random luminance only in one of these dimensions. The properties of the detection mechanism employed by the visual system were studied by measuring contrast energy thresholds for complex spatial patterns as a function of area in the presence of white pixel noise. Human detection efficiency was obtained by comparing human performance with an ideal detector. The stimuli consisted of band-pass filtered symbols, uniform and patched gratings, and point stimuli with randomised phase spectra. In agreement with the existing literature, the detection performance was found to decline with the increasing amount of detail and contour in the stimulus. A measure of image complexity was developed and successfully applied to the data. The accuracy of the detection mechanism seems to depend on the spatial structure of the stimulus and the spatial spread of contrast energy.

Image forming apparatus and method for processing image noise using the same

Abstract: An image forming apparatus is provided. The image forming apparatus includes an output unit to output a density pattern, a detector to detect the output density pattern, a signal extraction unit to extract an image noise signal from at least two sensing areas of the detected density pattern, and a control unit to determine if image noise generated on the detected density pattern is one-dimensional noise or two-dimensional noise based on the extracted image noise signal.

On the new filtering technique of noise attenuation in color images

Abstract: A new filter class for multichannel image processing is introduced and analyzed. The new technique of image enhancement is capable of reducing impulsive and Gaussian noise and it significantly outperforms the standard methods of noise reduction. In the paper, a smoothing operator, based on a random walk model and on a fuzzy similarity measure between pixels connected by a digital geodesic path, is introduced. The efficiency of the proposed method was tested on standard color images using objective image quality measures. Obtained results show that the new method not only outperforms standard noise reduction algorithms, but has some interesting features useful for segmentation of noisy color images.