Originally Posted by
MechEngr
Looks like contamination or (oh no!) a scratch. If it lost a channel it would be a single color, such as cyan or yellow or magenta. If it lost all channels it would be black. An adaptation is to turn the slide 180 and scan it a second time and then use the second to correct the first - which is a lot of pain, but is doable.
In this case you could crop it without losing too much (though you may not agree)
