I haven't found a way of changing the colour, pixel by pixel, to that of nearby pixels. I've tried cloning but that tends to be too coarse a tool and changes several pixels at once. My need for this facility is to sharpen some areas of a photo where quality has been lost in the scanning process. The faces are smudged and need retouching. Can someone help here? Many thanks.
The smallest brush tip size will be one pixel in diameter unless you've changed it. To check, make sure that the Brush Tip Tab is ticked on the View menu, select the Clone Tool and then right-click on the chosen brush and click Brush Options. You should find that you can clone one pixel at a time. (Each tool has its own brush tip setting, so you have to select the Clone Tool before you choose the brush.)