Millennium Bridge and St Paul's
This is an example of a rescued photo. It is a 3 shot HDR, however sometimes on the Millennium Bridge there can be a little movement when people walk nearby. This affected the Ev 0 shot, and when merged in Photomatix the result was not as crisp as I would have liked.
In order to rescue this I used a frequency separation technique. I loaded the Photomatix image and the Ev -2 image as layers in Photoshop and aligned then. I then duplicated the crisp Ev -2 image twice. On the first copy I applied a gaussian blur. On the second copy I used the apply image process from the edit menu and did a subtraction against the blurred copy. I changed the blend mode of this layer to linear light. The end result of this is that the tone information is on one layer and the texture/detail information is on another.
I did the same with the sharp Ev -2 image. Finally I put the detail information layer from the crisp image over the tone information from the Photomatix layer, with the linear light blend and ... hey presto ... I have all the sharpness from the Ev -2 along with the tones from Photomatix.
May seem like a long process but it is certainly easier than going back to re-photograph it at 4 am in the morning!