[Alt-photo] Re: Stochastic screening in Gum

Sandy King sanking at clemson.edu
Sat Dec 7 20:05:42 UTC 2013


Kees,

If you look at an inkjet negative with a magnifying glass the pattern of ink dots does look like a random stochastic pattern. I print digital negatives for monochrome carbon transfer printing with an Epson 7800 with QTR and a profile that I developed especially for my carbon tissue and sensitizing procedures. My negatives have a fairly high density range, about log 2.35, and with them it is definitely possible to print a continuous tone step wedge with no mechanical failure in the highlights.

Sandy




On Dec 7, 2013, at 5:37 AM, Kees Brandenburg wrote:

> Hi Peter,
> 
> As a first remark I think that an inkjet dither is in it's nature also 'stochastic'. Maybe that's one of the reasons why these negatives print so well with long (and short) scale processes. Even highlights in carbon which are a known difficulty with continuous tone negatives. Charles explained this before.
> 
> I have also been experimenting with a mac application called Icefields by isisimaging.com. This program can convert image files to a FM (frequency modulated) stochastic file. As I did not find a film output service anywhere near where I live I tried printing these files with my inkjet printer(s) with quadtonerip. There I noticed some interference between dots and the screened image file and I stopped testing. Maybe I should experiment more with the output settings. Still looking for someone that can output these fileswith on film.
> 
> kees
> 
> 
> 
> On 7 dec. 2013, at 00:21, Peter Friedrichsen <pfriedrichsen at sympatico.ca> wrote:
> 
>> Has anyone applied a stochastic screen to gum printing? This is a half tone technique that uses dot frequency to emulate color/greyscale. The smaller the dot size, the more photographic the rendition. My UV box generates diffuse UV light so I think that may not be as effective as a more point sourced arc type UV lamp.
>> 
>> Has anyone done anything like this before? I was wondering what the minimum dot size that could be realized from a contact negative?
>> 
>> Peter Friedrichsen
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