Abstract
The objects with different thermal infrared emissivities are taken simultaneously into a pixel of a remotely sensed multispectral image, and the proportion of an object changes with every pixel according to the altitude of the observation aircraft and the conditions of the region. Therefore, for a thermal infrared image, one cannot distinguish between the true change of the surface temperature and the apparent change of it caused by the change of the proportion of an object in the pixel. The exterior product image processing by using the image information of the visible channels adjusts the emissivity change caused by the change of the proportion, i. e., it removes the apparent temperature change on the thermal image.
Consequently, the temperature change on the processed image gives the true temperature difference pattern which is independent of the proportions of the various objects on the earth's surface. The emissivity compensation method based on the exterior product processing has the following features.
1) In this method it is not necessary to know the object's proportion in a pixel. It is an important practical advantage in application.
2) Visible images are used very effectively, namely, the mixed arithmetic processing of the thermal infrared image and the visible images is given in the compensated image.
