Presently the lookup table is adopted when corresponding relation between the position of remote sensing images and the geographic coordinates

which are involved in ground system engineering of geostationary satellites. For the corresponding geographic coordinates of sub-pixel or corresponding point of nonstandard grid nodes

which are not in lookup table

bilinear interpolation have to be introduced so that the precision loses remarkably for the image location. By deducing the formulas of geostationary satellite normalized projection at the condition of three-axis ellipsoidal parameter

the reversible equation from longitude/latitude to position on unit plane is established

which provides the mathematical reliance for lookup table for satellite image engineering. And corresponding match parameter for FY2-C application is provided after comparing with the practicing data of lookup table. The same procedure is applied to the situation of geographic coordinate system

but the inverse problem needs numerical solutions. The inverse method of geocenter coordinate system may be used as approximation when ellipsoidal parameter is close to sphere

while not applicable for fine image processing. The possibility of the application in FY2-C engineering of this reversible formulas is also discussed

with the analysis of the error distribution compared with practical data and the selection of applicable parameters for best fitting actual data.