Many radial distortion functions have been presented to describe the mappings caused by radial lens distortions in common commercially available cameras. For a given real camera, no matter what function is selected, its innate mapping of radial distortion is smooth, and the signs of its first and second order derivatives are fixed. However, such differential constraints have been never consider...

Endoscopic images are strongly affected by lens distortion caused by the use of wide angle lenses. In case of endoscopy systems with exchangeable optics, e.g. in bladder endoscopy or sinus endoscopy, the camera sensor and the optics do not form a rigid system but they can be shifted and rotated with respect to each other during an examination. This flexibility has a major impact on the location...

Perspective distortion occurs due to the perspective projection of 3D scene on a 2D surface. Correcting the distortion of a single image without losing any desired information is one of the challenging task in the field of Computer Vision. We consider the problem of estimating perspective distortion from a single still image of an unstructured environment and to make perspective correction whic...

Multi-bit ΣΔ modulators have become the preferred option for high performance, low power cellular GSM applications. When using multi-bit quantization, modulator performance becomes extremely sensitive to the internal digital-to-analog converter (DAC) non-linearity. DAC designs must fulfill linearity, power, and speed requirements for GSM while at the same time enabling dynamic element matching ...

Introduction: Gradient coils may be replaced on MRI systems as part of hardware upgrades or as a result of hardware failure. These events could introduce a step change in longitudinal quantitative neuro-imaging studies. Gradient winding errors cause even nominally identical gradient coils to differ in their field. Additionally the precise alignment of the gradient coil in the magnet and the act...

Additive iterative method in combination with averaging of dithered samples is designed for self-correction of ADC linearity error in the paper. Iterative method is one of the automated error correction techniques. Dithering is a special tool for quantizer performance enhancement. Dither theory for Gaussian noise and averaging has been used for exhibition of method abilities in ADC characterist...

Bronchoscopy is a commonly used clinical tool that provides a direct image of the bronchial lumen. However, bronchoscopy has seen little use as a quantitative measurement tool, mainly because of the wide-angle lens which distorts the image. The present authors have tested the ability of numerical algorithms and commercial software to correct for this distortion. Test objects of known size were ...

Due to the optics used in endoscopes, a typical degradation observed in endoscopic images are barrel-type distortions. In this work we investigate the impact of methods used to correct such distortions in images on the classification accuracy in the context of automated celiac disease classification. For this purpose we compare various different distortion correction methods and apply them to e...

The main advantage of backward over forward adaptive coding schemes is to update the coding parameters with the data available at the decoder, avoiding thereby any excess bit rate. In this work, the performances of two practical backward adaptive transform coding schemes are analyzed in terms of rate and distortion for two transforms: the KLT (Karhunen-Loève transform) and the LDU (based on a L...