When scanning large format negatives I discovered that I was often clipping highlights and shadows without realising it. It wasn’t until I opened the massive files in Photoshop that I discovered the clipped highlights and/or shadows. After waiting a long time for a high resolution scan to complete it’s a bit frustrating to have to start again after a tweak to the histogram in Epson Scan. Even worse if the tweak isn’t enough and it’s still clipped after the second scan!
My solution is to be more careful to analyse and set the white & black points before scanning the whole frame. I do this by reducing the size of the scan frame to a small box and then move it around the image, checking and adjusting histogram.
Move the box over a small highlight area, then modify the histogram white point to make sure nothing is clipped. Then do the same for a shadow area with the black point.
Here’s an example of how I originally set the points, which resulted in clipped highlights. When the whole frame is selected, the small area of highlights does not show up on the histogram resulting in me choosing a white point of 134:
But after selecting a much smaller area of the frame where there are strong highlights, the histogram updates to show just what’s within the selection. This shows that the white point should really be set to 204 – a huge difference!
The resulting scan: