# RE: Simple & Stupid Curve Generator for Digital Negatives

From: Don Bryant ^lt;[email protected]>
Date: 05/28/04-05:27:03 AM Z

Thanks Loris!

> -----Original Message-----
> From: Loris Medici [mailto:loris_medici@yahoo.com]
> Sent: Friday, May 28, 2004 3:53 AM
> Subject: Simple & Stupid Curve Generator for Digital Negatives
>
> Hi Don,
>
> I) Determine your exposure time for black (using a blank negative and
> bracketing, just like silver-gelatine printing).
> II) Expose your paper with a digital 100 step tablet using the time you
> found in step I (I made the 100 step tablet in Photoshop; 10x10 squares,
> starting with 1% luminosity - ending with 100% luminosity, each square
> 2x2cm @ 360dpi - you may use a less accurate scale if you like)
> III) Inspect the print and determine the first clear square - this will
> be your 100% density value. Use the eye dropper on the 100 step tablet
> file to determine the 100% density value equivalent in the 256 scale.
> IV) Use the value you found in step III as "Max Value" in the following
> Excel file:
> http://www.geocities.com/loris_medici/loris_curve_generator_for_digital_
> negatives.xls and create a curve using values in A column as input, and
> values in D column as output.
> V) This will give you a good starting point (assuming you're printing
> black-only or quadtone and your B&W output is pretty linear), print a
> photo which also includes 21-step wedge, evaluate & fiddle a couple of
> times.
>
> Hope this helps - I made my cyanotype curve using this method; it works
> for me.
>
> Regards,
> Loris.
>
> > -----Original Message-----
> > From: Silver Plated [mailto:dstevenbryant@mindspring.com]
> > Sent: Thursday, May 27, 2004 8:27 PM
> > Subject: Building PS curves for alternative processes with
> > the Inkjet Companion
> >
> >
> > Good Afternoon Everyone,
> >
> > Recently I purchased an Epson 2200 (an a 1280) and this past
> > weekend I had an opportunity to make a digital inkjet
> > negative to try printing as a toned kallitype print. Before I
> > go in to the particulars of my results and questions let me
> > point out that to make the negative I used Dan Burkholder's
> > Inkjet Companion Template, using his curve for palladium
> > prints. Additionally my monitor is calibrated and profiled
> > and I'm using Pictorico OHP for the inkjet negative
> > substrate. I choose the kallitype process since it is
> > relatively inexpensive.
> >
> > I knew that using Dan's curve would most likely require
> > adjustments to produce a good result, in fact I hoped that
> > the print would need adjustment to provide myself with the
> > opportunity to learn how to make adjustments to curves for
> > various processes. The final print was extremely flat. There
> > was very little differentiation in most of the steps in the
> > included step wedge on the print. This is in contrast to the
> >
> > on my densitometer. Most of the mid-tone steps had a reading
> > of about .25 to .35 (I'm working from memory here).
> > Additionally I have not established the minimum print time
> > for black but I assume I'm pretty close since the 100% step
> > was 1.35. I plan on establishing the minimum black time this
> > weekend with a blank piece of OHP.
> >
> > My question today is; is there a way to correlate my
> > densitometric readings that will result in the desired
> > changes in the PS curve to produce good separation. Also how
> > much difference in log density values should one expect to
> > see in the step wedge mid-tones? Also if I read the
> > transmissive values on the negative are there aim points for
> > the differences from step to step that one should observe?
> >
> > Hopefully my questions seem rational and clear, if not,
> > someone, anyone please correct me!
> >
> > Also as time permits I plan to test Keith Schriber's
> > colorization values and curves along with several other
> > curves different individuals have sent me.
> >
> > Thanks,
> >
> > Don Bryant
Received on Fri May 28 05:30:53 2004

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