Selective Colour to Greyscale (Before)

 

The above B&W image shows what can happen when we simply convert form colour to greyscale. The rear of the boats and the stone wall shown left of frame are on the dark side even though each was well separated from adjacent elements in the original colour image. Can it be fixed?

 

 

Notice that the rear of the right most boat is a lot brighter as is the shop front and stone wall. There are other areas of this image were the correction is much more subtle. However, I think you will agree that the final result is a lot better than the original conversion.