Error analysis of image representations for sources near to a dissipative earth

Various image representations for sources above a dissipative earth are introduced. A criterion for assessing their accuracy is given. Some of these image representations comprise purely discrete images, a purely continuous image or a mixture of both types. It is shown that the error in any representation is a function of the height of the field point from the earth´s surface. A mixture of a discrete image and a simple continuous image can lead to a negligibly small error for field calculations over a wide range of the height of the field point. This means that the image theory can offer simplicity and accuracy in many application such as geophysical prospecting of the earth.