Perfect, thanks all I have shots of the Pantheon from various times of day John. I'll scan through them and check out the differences, I can see now that the building could do with a little more illumination.
Ed, that's a great point. I work on a laptop and the viewing angle definitely affects the image appearance.
Thanks Dougie, the majority of the shots so far are historic ones taken on holiday with more thought to composition and appearance and very little knowledge of exposure etc.. (all jpegs). I'm taking recent shots in RAW with much more thought to exposure, histogram etc.. I'll have a play with that, I can see where contrasty images are definitely hard to bring out the detail from shadows. I'll have a play with exposing to the left and see how it goes.