1. Field of the Invention
The invention relates to an image processing method, and more particularly to image processing methods with consideration of the distribution characteristics of the image.
2. Description of the Related Art
With the development of digital signal processing, digital image processing technology has also advanced. The digitalization of an image converts an image into a form which can be stored in a computer's memory or some storage device such as a hard disk or CD-ROM (Compact Disk Read Only Memory). Once the image has been digitalized, it can be operated upon by various image processing operations, such as image compression, image enhancement . . . etc.
In computer graphics, image enhancement improves the quality of the digitally stored image by adjusting the pixel values which form the image, or by further using filters for altering images in various ways. Before image enhancement processing, the image can be analyzed first. Image analysis can be performed utilizing statistic graphics or functions that reveal the characteristics of the image, such as a histogram representing the pixel value distribution of the pixels forming the image.
After analyzing the image, enhancement can be performed according to the analyzed results. There are many types of image enhancements, including brightness adjustment, contrast enhancement, noise removal, image size alerting, image cropping, and unwanted image removing, etc. Brightness adjustment is executed by applying a gain value to the pixel value forming the image for increasing or decreasing the pixel values. Contrast enhancement is executed by increasing or decreasing the contrast between high pixel values and low pixel values. Noise removal is executed by removing the noise in image, such as JPEG (Joint Photographic Experts Group) artifacts, dust, scratches, and so on. Image size alerting is executed by scaling the images and making them larger or smaller. Image cropping is executed by creating a new image by removing a desired rectangular portion from the image being cropped. Unwanted image removing is executed by removing some unwanted objects in the image and draw focus to the image subject.
Although image enhancement is used to improve the image quality, it also causes some image distortion when changing the characteristics of the image. Thus, image analysis and enhancement methods that can reduce image distortion need to be developed.