1. Field of the Invention
The present invention relates to processing of digital images. More particularly, the present invention relates to methods for digital image sharpening while avoiding noise amplification.
2. The Prior Art
Digital images often lack edge sharpness, for example, due to out of focus or insufficient optical capabilities of imaging devices. To increase image sharpness, digital imaging systems and software allow for image sharpening. At the pixel level, the sharpening operation enhances the local contrast between the pixel under consideration and its neighbors.
Unfortunately, digital images usually contain noise introduced to the image during its acquisition and the traditional image sharpening solutions can significantly amplify the level of the noise, thus reducing both the value and practical usability of the image. To reduce this side-effect while enhancing the edges in a digital image, existing sharpening solutions usually rely on the following approach. Noise is first suppressed via denoising prior to applying the sharpening method to the image. Unfortunately, resulting images often lack details and natural appearance and may also suffer from some blur effects and amplification of the noise left after denoising. Therefore, a different solution is needed, at least when it comes to high-quality digital imaging.