----- Original Message ----- From: "Colin Maddock" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, December 16, 2001 7:32 PM Subject: Re: filmscanners: VueScan Histogram
> David Gordon asked: How do you know where to clip the black and white points? > > I always leave black clipping at 0, and white clipping at a minimal amount, perhaps 0.1, so that the VueScan scan contains all the tonal range that was on the neg/slide. *From my observations if you just scan with the WP at 0.1 as default, you can compress the tonal values rather than making sure the image ocupies the full range available. If your image allows a WP of say 0.4 just before clipping then the available range isn't wasted in the 0-0.4 area* Any further clipping of the end points for cosmetic reasons etc can be done as part of the operations in the image editing program, using, say, the Info facility to search the levels. *Making sure the actual points at just before clipping are fully filling the histogram maximises the image quality output to file etc. I also found before the histograms were implimented that the best visual tonal range on screen ie unclipped whites but not vailed or flat as is often the case with WP <0.3 actually do fill the histogram perfectly. The image editor then can do the 'cosmetics' if required on an image mapped to make use of the full available dynamic range.* Philip Elkin