[filmscanners] RE: Intentional clipping

["Alessandro Pardi" <alessandro.pardi@inferentiadnm.com>]

I fully agree with Tony on this subject. Maybe you all already know it, but
an easy way to see what you're clipping when setting levels in Photoshop is
to press Ctrl+Alt while dragging the small arrows: the screen turns white,
and when the arrow reaches the first pixels in the histograms the parts of
the images corresponding to those pixels turn to black, so that you have a
visual perception of what's becoming full black (or full white, if you're
clipping highlights).
BTW, sometimes the whitest pixels in an image are just scratches or dust
spots (talking negatives here: for slides they are the blackest), so in this
case some white clipping is recommended, and the above technique is really
useful (unless you spot your image before setting levels, of course).

Hope this helps,
Alessandro Pardi

> -----Original Message-----
> From: Tony Terlecki [mailto:ajt@mrps.demon.co.uk]
> Sent: mercoledì 29 gennaio 2003 20:34
> To: alessandro.pardi@inferentiadnm.com
> Subject: [filmscanners] Re: Intentional clipping
> 
> 
> On Wed, Jan 29, 2003 at 04:39:39PM +0100, Tomek Zakrzewski wrote:
> > Now that I have good software that prevents highlights from clipping
> > (VueScan and NikonScan) I wonder in what circumstances should I
intentionally clip 
> some highlights.
<snip>
> > And what about shadows? Do I always should leave the left 
> (shadow) side unclipped? What area should be clipped to black?
> > Any examples of highlights and shadows clipping?
> >

> 
> My comments here are directed more towards B&W film...
> 
> My own personal preference is not to clip highlights other 
> than specular. A common area that is often at the point of being blown out

> is sky. While is is tempting to clip pixels there you will find if you
ever 
> want to burn in the sky later that there is no grain texture left because
of the 
> clipping so any burning in will simply result in a featureless grey.
> 
> Shadows are a different matter - there I clip any shadows 
> that don't contain detail that is significant to the image. Personally I
think 
> that many people set their black point far too conservatively, often at
the very 
> first black pixel from the scan. What this often does is reduce the 
> overall contrast of an image to the point where the image loses some
impact.
> 
> While scanning can now capture the huge range of scene brightness
> recorded on film (10-12 stops easily on B&W film) you should 
> always remember that you still have to print onto paper which has a far
more 
> limited brightness range. The more you try and keep from the negative the
more 
> you have to sacrifice in contrast and often impact in the print.
<snip>
> 
> Lots of generalisations there I know but hopefully some of it 
> you might
> find useful.
> 
> 
> --
> Tony Terlecki
> ajt@mrps.demon.co.uk
> 
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