A method for detecting edges in an image is disclosed along with corresponding apparatus and system for accurately extracting edges in the image. The edge detecting apparatus comprises a reading means, an image gray-level statistical means, an image classification means, a segmenting threshold generating means, an edge criterion determining means, and an image edge extracting means. The present invention realizes a reliable and accurate method for detecting edges in an image so as to extract edges in various file images.
Radiometric calibration of an image capture device (e.g., a digital camera) using a single image is described. The single image may be a color image or a grayscale image. The calibration identifies and analyzes edge pixels of the image that correspond to an edge between two colors or grayscale levels of a scene. Intensity distributions of intensities measured from the single image are then analyzed. An inverse response function for the image capture device is determined based on the intensity distributions. For a color image, the radiometric calibration involves calculating an inverse response function that maps measured blended colors of edge pixels and the associated measured component colors into linear distributions. For a grayscale image, the radiometric calibration involves deriving an inverse response function that maps non-uniform histograms of measured intensities into uniform distributions of calibrated intensities.
