HARRY01

I have created an image file of a view from GoogleEarth. The view covers in vertical direction the Netherlands down to the bottom of Spain. The file size is 1400 * 820 pixels. The latitude and longitude various on different positions on the left, bottom, right and top side of the image, I think because of the projection. I have the LAT/LON of the four edges of the view. I load the image into a program and then I have to add a number of markers to the image. I have the coordinates of the markers; these should be converted to the x and y position of the image in order to draw the markers. The same applies in the opposite direction. The user can touch the screen. In order to to what he wants, I have to convert the x and y of the screen touch to the LAT/LON. I am a layman in mathematics. I can only apply formulas, but cannot define them myself. Can somebody help me? Thanks in advance, HARRY01