Now, if I have a world file like this:
...can I say that the "real" upper left corner of the image (upper left corner of the upper left pixel) is:
X = 691200.0 - (32.0 / 2) = 691184.0
Y = 4576000.0 - (-32 / 2) = 4576016.0
...and should I use these coordinates if I want to use the image with Bing Maps or Google Maps (after converting to Lat/Long off course), or should I stick with original ones (pixel center coordinates).
I just realized that the .tab file associated with the map has coordinates of the upper left pixel (0,0) calculated the same way as in my question above. Not sure about the exact formula but resulting coordinates are the same - shifted left for half of the pixel width and up for half of the pixel height. Now I'm pretty confident that this is the right way to do it.