Digital BW, The Print

Hello Tyler, Paul D.,

>I can think of no possible reason RGB 0, 0, 0, would print 
>differently from two different files. I would be inclined to go 
>back and carefully verify everything, all printing settings for 
>both, double check file values, etc..

Sorry if I didn't explain well, it's not from two files.  Both prints
were from the same grayscale image, same printer, paper, ink, and
settings.  The only difference was the 2nd print had a curve layer
added with a slight S-curve to increase contrast (a typical S-curve
where the black and white anchor points were not changed).  The
background is entirely solid black (when working up the image I
purposely selected out the background and made every pixel RGB 0,0,0).
 The background in the 2nd print had significantly better Dmax.



>>3) Why does adding more ink to an already 100% covered area of pure
>>black increase Dmax?
 
>Sometimes it does and sometimes it doesn't. Depends on ink, paper,
>printer. 

i.e. my reply to Carl - I found it didn't react the same on another
paper.


>It's also an (perhaps) assumption that 100% ink is in fact
>full coverage of the paper. I believe there is still a dot pattern at
>100%, the driver cannot simply open up and pour it down.

Yes, certainly there's a pattern.  Probably the pattern was simply
tightened up.  The real mystery is still why the S-curve would have
caused any change to begin with.



>with some ink, will have a higher dmax at something less than 100%,
>for example papers that bronze.

Hmmm..., that certainly adds some complexity. 



>There's something goofy going on. 000 is 000, context [contrast?]
>shouldn't be an issue

Exactly.  That's the big question.  I was hoping this was some known
phenomenon and someone like you would have the answer.  All we know at
this point is

1) The curve made a difference
2) The difference was significant on one paper and barely noticeable
on another.

I'm beginning to think we'll have to chalk this one up to "Twilight
Zone" <g>.

Thanks very much for the input.

Regards,
Clayton


Info on black and white digital printing at    
http://www.cjcom.net/digiprnarts.htm