In this exercise we are looking at correcting artefacts included in an image that should not be there, typically those caused by flaws in the camera equipment.Two that are looked at in detail are dust spots on the camera's sensor and lens flare.
I try to keep the sensor clean, especially when I start to notice dust spots, more noticeable on solid colours such as the sky on a clear day. Finding them in a mix of colours is a lot harder.
Looking back I had problems in finding an old image with such spots, which I suppose is good, but he is one with a minor spot shown in the white square, though not easy to see at this resolution.
To fix this is very straight forward using the spot healing brush, just select a brush size slightly larger that the spot and click. I find it very hard to see any join and remnant of the original blemish.I feel that this form or alteration is valid as the spots should not be there and are introduced through flaws in the camera. Also removing them is virtually transparent to the viewer, so that the feeling of modification, will in almost all cases, not be known.
The second flaw looked at was lens flare. Again an artificial artefact but one that is a lot harder to remove. I could not find such an image in my collection, but I used photoshop to add a lens flare through the filter menus.
Personally, I like lens flare but in some cases this may become too distracting or spoil a particular part of an image and therefore needs some treatment. As described in the notes I used the clone tool, with the mode being set to colour and darken. On my first attempt I found that I needed to reduce the opacity to around 50% as the changes were too strong, I also found that using a colour mode has changed the colour of the highest head of grass to a blue tinge. In hindsight I should have used a layer mask to make the changes, I then could have gone back and deleted the changes over the head of grass to bring back the original.
Overall the technique has been successful, but there are traces to me that are quite obvious that changes have occurred and therefore I do not feel that this is a valid editing process.Personally I feel that the lens flare should be retained, and if it cannot be removed without having obvious water marks then the image should be left as is or assigned to the bin.