An IHS-Based Fusion for Color Distortion Reduction and Vegetation Enhancement in IKONOS Imagery

In IKONOS imagery, both multispectral (MS) and panchromatic data are provided, with different spatial resolutions. IKONOS images can be fused or pan-sharpened for the visual interpretation of large-area-scale applications. To date, many image fusion techniques have been developed. In particular, the intensity-hue-saturation (IHS)-based methods are well known in quick image pan-sharpening. However, most of these processes produce color distortion due to the unnatural spectral response of IKONOS sensors, particularly in vegetated areas. Hence, many recent methods make use of vegetation enhancement in order to correct the unnatural color appearance. Generally, this enhancement is accomplished using vegetation indexes (VIs). A new fusion approach that produces images with natural colors is proposed. Moreover, in this technique, a high-resolution normalized difference VI is also proposed and used in delineating the vegetation. The procedure is performed in two steps: MS fusion using the IHS technique and vegetation enhancement. Vegetation enhancement is a correction step, and it depends on the considered application. The new approach provides very good results in terms of objective quality measures. In addition, visual analysis proves that the concept of the proposed approach is promising, and it improves well the fusion quality by enhancing the vegetated zones.