Image signal processor and method for image enhancement

#1. Field of the Invention

#The present invention relates to image signal processing techniques, and in particular relates to image signal processing techniques for image enhancement.

#2. Description of the Related Art

#The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

#FIG. 1 shows an arrangement pattern of the Bayer filter.

#FIG. 2 illustrates the processes of the image signal processing (ISP) technique in the prior art.

#The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. For simplicity, in the discussion that follows, an image signal processor or an image signal processing method which processes an RGB signal is used as an exemplary embodiment. It should be understood, however, that the apparatus and method of the present invention may be applied to other color signal, such as CYMK signal. Specifically, when the color signal is the RBG signal, the first, the second, and the third component of the color signal is respectively selected from a red, a green, and a blue component of the RGB signal; and when the color signal is a CYMK signal, the first, the second, and the third component of the color signal is respectively selected from a cyan, a yellow, a magenta, and a black component of the CMYK signal.

#FIG. 3A is a schematic diagram of an image signal processor for performing image enhancement according to an embodiment of the present invention. The image signal processor 300 receives an RGB signal of each pixel of an image, for example, from a demosaicking procedure, which includes red (R), green (G) and blue (B) components, and directly performs image enhancement on the RGB signal without the color space conversion (CSC) which turns the RGB signal into the luminance and chrominance signal. The image signal processor 300 at least comprises an image enhancer 310, a gain generator 320, and a gain multiplier 330, where the image enhancer 310 receives one component, and the gain multiplier 330 receives the other two components of the RGB signal.

#The image enhancer 310 is used for performing image enhancement, such as noise reduction or sharpness enhancement, on one component of the RGB signal. In a preferred embodiment, the image enhancer 310 performs image enhancement on the green component G of the RGB signal because the green component is usually created with a higher sampling rate and higher SNR. Note that this example which is shown in FIG. 3 and will be discussed later is intended for illustration only, and the present invention should not be limited thereto. In other embodiments, the image enhancer 310 may focus on processing the red component R or blue component B instead. In this embodiment, after the image enhancement for the green component G, the image enhancer 310 produces an enhanced green component G_out.