[alt-photo] Re: Print Density Estimation From Scan

[EJ Photo]

Peter, they have to do with control and my understanding of the process you
are using. Do you have control of the process? It has to do with
understanding what tools you are using. They are simple to answer too.  : ) 

And they just popped into my head so I asked them. 

Eric Neilsen
Eric Neilsen Photography
4101 Commerce Street, Suite 9
Dallas, TX 75226
 
www.ericneilsenphotography.com
skype me with ejprinter
www.ericneilsenphotography.com/forum1
Let's Talk Photography
 
-----Original Message-----
From: alt-photo-process-list-bounces at lists.altphotolist.org
[mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of
pfriedrichsen at sympatico.ca
Sent: Saturday, December 11, 2010 4:26 PM
To: The alternative photographic processes mailing list
Subject: [alt-photo] Re: Print Density Estimation From Scan

Eric,

I am not sure why any of this would matter if a step wedge is being 
scanned with the print? Can you elaborate on those questions?

Peter Friedrichsen



At 11:47 AM 12/10/2010, you wrote:
>Peter, What are you doing to lock down your base scan? What software and
>scanner are you using.
>
>Eric Neilsen
>4101 Commerce Street, Suite 9
>Dallas, TX 75226
>214-827-8301
>
>Let's Talk Photography
>www.ericneilsenphotography.com
>SKYPE ejprinter
>
>-----Original Message-----
>From: alt-photo-process-list-bounces at lists.altphotolist.org
>[mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of
>Peter Friedrichsen
>Sent: Wednesday, December 08, 2010 6:18 PM
>To: The alternative photographic processes mailing list
>Subject: [alt-photo] Print Density Estimation From Scan
>
>Hi All,
>
>Just wondering if anyone is willing to comment on my method of
>estimating print density using a scanner and a Souffer reflective step
>wedge.
>
>The density estimate is based on comparing only the red binary values
>with those of a Stouffer step wedge of 0.15 density increments per
>step, and this is done in photoshop by browsing pixels. The red
>channel was chosen because of an iron stain that affects
>predominantly the green and blue channels. The image I used is
>labeled print 3a and can be found here:
>
><http://picasaweb.google.com/pgfriedrichsen/FerricGumProcess#>http://picasa
w
>eb.google.com/pgfriedrichsen/FerricGumProcess#
>
>
>The whitest area in the sky on the left side and about 1/2 way up
>gives me a value of 225. The first shades (lightest greys) above the
>left side of the roof give me 221, and the darkest shades just under
>the eaves troughs gives me 42. I have chosen to use the lightest grey
>values because there may be blown highlights and I don't want to
>include those in the density range. So, here is what I am using in summary:
>
>image density-----------pixel value-------step wedge # at this value
>
>lightest greys--------------221---------------less than 2 (use two as
>conservative)
>darkest greys---------------42---------------10
>
>difference density=10-2=8
>
>now I multiply 8.0 by the step density difference value of 0.15 per
>step: 8 x 0.15=1.2
>
>I get a density of 1.2.
>
>Anyone wish to comment on whether this is a sound technique for a
>reflective density measurement?
>
>Peter Friedrichsen
>
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