[rollei_list] OT: Inverting an image digitally, was: Wooden Tripods
- From: Aaron Reece <oboeaaron@xxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Thu, 1 Nov 2007 09:24:38 -0400
On Oct 31, 2007, at 5:21 PM, Mark Rabiner wrote:
Thing is don't you have to make a film positive then from that make
a film
negative? That's what kills me.
No, with Photoshop or other image manipulation programs, you can
invert the greyscale values in your image to create the negative
directly. In Photoshop the hotkey is cmd-i on Macintosh, not sure
about Windows. Probably Ctrl-i. Someone wrote a book a few years ago
on the subject of preparing images using Photoshop for output on an
offset press using transparency material to produce a large-format
negative that is then contact printed. At the time, it was important
to use a professional offset printer since the resolution was an
order of magnitude (or more) higher than what you could get from an
inkjet printer printing onto transparency material. Although inkjet
printers with DPI ratings of above 5000 now exist, they typically are
only rated for a maximum of 300 DPI when printing onto transparency
material. Another thing that it is necessary to do before printing
out your "negative" is to adjust the contrast curve of the digital
image to adapt it to the curve of the (silver halide) printing paper
you will be using. Once the curve of the paper is established, a
custom curve can be set up and saved in Photoshop, and reused on each
new image.
Here is a link to the site of the book mentioned above:
http://www.danburkholder.com/Pages/main_pages/book_info_main_page1.htm
I've never gotten around to trying this technique, although I do find
it intriguing.
Best regards,
Aaron Reece
Oswego, NY, USA
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