I have just returned from a trek that I cannot repeat. In archiving the photos I took on this trek, I realised that for one series of photographs I had something on the lens (probably yak shit). This has resulted in this series having the same flaw (it looks like smoke drifting upwards into the sky). Obviously the effect varies from frame to frame depending what lies within the spoilt area - a lot have sky in this area; another lot have mountains in this area (and so the effect is not so great). This flaw affects about 28 shots out of approx 230.
Does anybody know of an approach that will allow me to remove the effect of this flaw consistently across all the affected shots. I am not looking for detailed instructions applicable to a particular software package, but rather an approach to this type of problem and its correction using image manipulation software.
If it is relevant, the software I use normally is Corel Paintshop Photo Pro X3. The shots concerned were taken on a Nikon D70s, and are all in RAW format.
EDIT I was asked for a copy of an image so you could see what the flaw was. Attached is a small JPEG with the flaw roughly marked in. I do appreciate that this particular image may be very simple to fix, as there is a plain sky I can use to clone. This is not the case with all of them. In addition, I asked originally for a solution to remove this flaw CONSISTENTLY across all the affected shots. A solution for one image only is less desirable.