[rollei_list] Re: Wonderfully put, Neil (was: Are Enlargers Obsolete?)
- From: Ardeshir Mehta <ardeshir@xxxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Sat, 23 Apr 2005 12:38:38 -0400
WONDERFULLY put, Neil. I think you are QUITE right. I was not conscious
of many of the things you said below, but now that you have brought
them to our attention I get your point totaly. Especially about the
tonal range.
Yes, it seems that both digital and optical processes have their place
and will have their place in photography and should continue to coexist.
On Saturday, April 23, 2005, at 09:34 AM, Neil Gould wrote:
> Just as there are differences between analog and digital image
> capture, there are differences between analog and digital processing
> and printing methodologies. We sometimes disregard that optical
> enlargement of images is a 3-dimensional process that has a secondary
> variable due to the fact that both the film and print material have
> grain structures.
>
> Forgive my returning to such elementary aspects of photography, but I
> hope that it will bring to light some of the reasons that digital and
> optical methods should continue to coexist. The grain structures of
> film and print material are 3-dimensional as grains have thickness.
> The secondary variable is that the grains are not arranged in a flat
> matrix, but are suspended in a "thin pile" for lack of a better way to
> describe it at this early hour. The projection of light through this
> pile can create a very broad range of tonality.
>
> Optical prints are created by light projected through the film's pile
> onto another pile whose "resolution" automatically varies with print
> size, print material and processing methods. There is no single
> representation of the image on film, only a particular instance as a
> result of the process. As one enlarges optically, one is creating a
> print with a resolution that *increases* with size. In other words,
> there are more grains on the print material representing the same area
> of the film as the size of the print increases. Therefore, the shadows
> created by light projecting through the 3-dimensional grain pile are
> more accurately represented as print size increases. Of course, other
> factors involved in optical projection may act to diffuse the image on
> the print.
>
> For scanned film, one should consider the impact of artifiacts and
> quantization. One artifact that may limit the usefulness of a scan is
> grain aliasing, where the grain in the film has been emphasized and
> misrepresented as a 2-dimensional element of inaccurate density. There
> are ways to reduce this artifact, but at the cost of sharpness. Unlike
> optical enlarment, the creation of the 2 dimensional pixel matrix is
> the final arbiter of image detail (whether direct image capture via
> digital camera or by scanning film).
>
> Also, quantization restricts the tonal range that can be represented
> by a pixel. As print size increases, the tonality represented by the
> matrix can result in banding, where larger areas of the print have the
> same density value. As print size increases, there is no more
> information available about the tonality as there is in optical
> enlargement. I believe that it is the combination of artifacts and
> quantization that differentiates the results of digital vs. optical
> enlargement that you describe as lacking "pleasing aesthetic effect".
>
> My above opinions are derived more from practical experience than
> theory, so I'm sure that others with a better technical background can
> flesh out the details and/or correct some of the representations that
> I've made.
>
> Best regards,
>
> Neil
Ardeshir <http://homepage.mac.com/ardeshir>
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