VueScan Histogram Raw Question on B&W Neg

A

Alan Smithee

I've scanned a black and white neg.
When I look at the levels in VueScan's histogram I can see the whole outline
of my tone distribution, on this particular neg there is a noticable peak
located centrally in the mid-tones quite obvious in VS's histogram which
goes very near to the top. When I look at the same data in PhotoShop opened
as either a Tiff or Raw saved from VS I've got clipped data -- the "top of
the mountain" is chopped off. The clipped grey area between is RGB values of
158 and 177. What's going on? One other thing while I'm here, the Raw file's
histogram plot shows up like it's been pushed "further to the right" when
compared to the same file which is just saved as a tiff, colour corrections
in VS are set to NONE. Film settings set to TMAX 400; CI set to 0.40. What
gives? What kind of correction is being applied that I can't see or control?
Auto Exposure? Should I lock it down to the Nominal 1.0 value?
 
R

Robert Feinman

I've scanned a black and white neg.
When I look at the levels in VueScan's histogram I can see the whole outline
of my tone distribution, on this particular neg there is a noticable peak
located centrally in the mid-tones quite obvious in VS's histogram which
goes very near to the top. When I look at the same data in PhotoShop opened
as either a Tiff or Raw saved from VS I've got clipped data -- the "top of
the mountain" is chopped off. The clipped grey area between is RGB values of
158 and 177. What's going on? One other thing while I'm here, the Raw file's
histogram plot shows up like it's been pushed "further to the right" when
compared to the same file which is just saved as a tiff, colour corrections
in VS are set to NONE. Film settings set to TMAX 400; CI set to 0.40. What
gives? What kind of correction is being applied that I can't see or control?
Auto Exposure? Should I lock it down to the Nominal 1.0 value?
Click to expand...
If you are saying that the top of the histogram is chopped off then that is
just a display problem of the histogram software. It is not resizing the
graph in the vertical direction properly. It has no effect on the actual
image. The only clipping you need to worry about are at the left and right
edges. If you have large peaks there you are probably clipping either
the highlights or shadows.
 
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