Included in the skyview.util package are two simple utilities that find the coordinate of a pixel in the image or the pixel corresponding to given coordinates. You can use them as:
java -cp skyview.jar skyview.util.CoordsPixel filename.fits 10.3 11.4
to find the pixel in filename.fits that is at coordinates 10.3, 11.4 (in the coordinate system used in the image) or
java -cp skyview.jar skyview.util.PixelCoords filename.fits 512 512
to find the coordinates for a given pixel (using Java counting where pixels begin at 0,0).