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Re: Digital Negatives with enough Tones for Pt/Pd

Nick Makris wrote:
> ... 1)  Have you produced a negative(s) that you subsequently printed and was
> the resulting print satisfactory or did it show promise?

working on ,but may show promise.  This is not my highest priority thing
to do.


> 2)  ... you are using TRI-X
> film that you develop with no exposure so that you are left with Base+Fog.
> Do you somehow prepare the film for use in your inkjet printer or how does
> that work?  What I mean is, I wouldn't have considered TRI-X to be a
> suitable medium for spraying ink.

The film is not developed, it is cleared only (fixed).  I do not want
any base+fog.  No other prep.  The ink is not sprayed.  I use an HP
DeskJet-970 with the appropriate inks.  Don't bother to ask about any
equipment I do not have.

> 3) My film scanner is an 8 bit scanner and I was wondering what control is
> supplied by your scanner software that allows you to set the bit level to
> scan? ...

Sorry, throw it away and get one capable of at least 12-bit.  That 8-bit
scaner does not have enough depth to scan negatives.period.  Even 12-bit
is limited by noise so that the negative must keep a reduced range from
what is typically used for Pt/Pd.  14-bit or even 16-bit should do the
job.


> 4)  Please confirm that each of your 3 scans are received by Photoshop as 8
> bit scans with a full range of 256 colors - this is somewhat confusing.

Each of my scans are scanned 12-bit and are 8-bit when saved by the
scanner and when opened in Photoshop.  12-bit is 4096 tones, 8-bit is
256, 12-bit has 16 times the tones of 8-bit.  One could make 16 scans of
each progresive 256 tones and store them in 16 files for a total of 4096
stored tones.


Nick Makris wrote:
> ... The text below was taken from the Photoshop 5.02 help file and it appears
> that Photoshop will import or open a file with 16 bits per RGB channel

THIS IS USELESS IF THE FILE DOES NOT CONTAIN A 16-BIT IMAGE (or one
greater than 8-bits).  The HP ScanJet 6300C scanner stores an 8-bit
image.


> The conversion of even an 8 bit file to a 16 bit mode (this would
> work with my 8 bit scanner) would then allow the selection of the low, mid
> and high tones that you spoke of, to be selected/deselected into 3 absolute
> registration images that could be saved individually. ...

WRONG.  8-bit scanning does not have the depth to scan negatives.period.


> The
> use of the levels, curves or transfer commands could then select the desired
> info
> for the final conversion to 8 bit for the printer.

WRONG.  Those functions will only fabricate 16-bit which must be used to
avoid round off errors when doing the math required of various
functions, but in the end you are left with only 8-bit info.  There is a
good reason why Photoshop does not have certain 16-bit functions such a
store, print, edit commands, filters.  Because it's not real 16-bit
data.

NOTE: If the 16-bit mode is not used to perform most of the functions it
can, round off errors will leave one with less than 256 (8-bit) tones. 
Make a gradient in RGB, change to CMYK, then back to RGB, do it in both
8-bit and 16-bit, compare the gradients (magnify).


-- 
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/