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[filmscanners] Blown highlights (was traffic)

Julian Vrieslander wrote:

> But this digicam does not, in my opinion, compete with a good film SLR.  We
> have quite a few vacation shots that were taken at the same spot using
> Cindy's 4500 and my F100.  The differences are not huge, but the scans from
> my F100 shots look better.  What is most noticeable to me, is that the
> highlights on the digicam shots tend to blow out more often.  The tonal
> variations look natural as you go from shadow into brighter areas, but then
> suddenly there is a featureless blotch that looks like someone spilled
> whiteout on the image.  I've read explanations that attribute this effect to
> the linear transfer function of the digital sensors.  They saturate
> suddenly, whereas with film you have an s-shaped transfer function that
> saturates more gracefully.

This is what I most dislike about a lot of images from digicams.

> Perhaps the digicam sensor blowouts can be avoided by carefully setting
> exposure to avoid clipping.  But this is not always possible.  Perhaps the
> problem is less serious with DSLRs, since they have larger sensors, more
> dynamic range, etc.

As far as I can tell, the unnatural blown highlights can also be caused by the 
in-camera sharpening, even if the exposure actually OK.  If you take a scanned 
image and sharpen it too much, it starts to get that same sort of look.

Obviously, most cameras allow you to decrease the amount of sharpening applied, 
but may still not turn it off completely.

I'm considering getting a digicam but I'm only looking at ones which have a RAW 
mode.  That way you can bypass the in camera processing completely, if you 
want, and use more advanced edge sharpening techniques or actions.

Al Bond


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