I scanned a postage stamp.
Here's the scanned image, as displayed in VueScan, before selecting a crop area:
After selecting a crop area, the same image looks like this:
I assume that VueScan is using the average luminance/colour values to adjust its assessment of the values it has scanned, but:
- what exactly is it doing?
- why is it doing it?
- is it possible to prevent it, so that it displays only scanned, and not adjusted, values?