Digital BW, The Print

1160
MIS sepia>neutral
Paul's curve's
0-100% step tablet/wedge

A group member emailed me a 100 step tablet (he can volunteer 
himself :-) which I've printed with the Neutral curve.
Examining it closely, I've identified 6x  spots where the adjacent 
square cannot be distinguished at all from it's 'lighter' neighbour.
these are 58/59%, 67/68%, 78/79%, 85/86%, 87/88%, 92/93%  

Now I need help on how to alter the curve - loading the curve on an 
adj. layer (on any rgb image), I can Ctrl tab or Shift Ctrl tab up 
and down the curve points on the curve and even enter the Input 
number manually between 0-256 and then I can raise/lower the Output 
number.
But the sep tablet i printed is in 0-100% points - so how do I find 
the flat points - how to convert them to the input and then output 
number(58/59%, 67/68%, 78/79%, 85/86%, 87/88%, 92/93%) ?

Hope I'm making sense ?
frankg

Hi Frank,
I know you got the 2.55 X the percentage formula for conversion to the 8 bit grey scale. What is even worse than flat spots, is a reversal in shading. I've sure done that many times in my experiments. They lead to strange solarized photos.

58% = 148
59% = 150

67% = 171
68% = 173

etc.

Greyscale step = ( 2.55 * percentage ) 

Best,
Alex

--- In DigitalBlackandWhiteThePrint@y..., "frankg_photo" <frank@f...> wrote:

>>
> But the sep tablet i printed is in 0-100% points - so how do I find 
> the flat points - how to convert them to the input and then output 
> number(58/59%, 67/68%, 78/79%, 85/86%, 87/88%, 92/93%) ?
> 
> Hope I'm making sense ?
> frankg

Only 'nearest' values are able to be inseted in the curves Input box ?

So far, working on my Red/Cyan curve only allows tweaking up to the 
255 unit mark ( of course) so what about the % values above that ?

58%=148 (nearest value 146 inserted) on curve = output 78 > changed 
to 79 - correct?

67%=171 (nearest) = output 145 >changed to 146

78%=200 = 254 output > changed to 255

And that's it ! No where to go with 85%,87%,92% flat points ?


--- In DigitalBlackandWhiteThePrint@y..., "B. Alex Pettit Jr." 
<a_pettit_jr@y...> wrote:
> Hi Frank,
> I know you got the 2.55 X the percentage formula for conversion to 
the 8 bit grey scale. What is even worse than flat spots, is a 
reversal in shading. I've sure done that many times in my 
experiments. They lead to strange solarized photos.
> 
> 58% = 148
> 59% = 150
> 
> 67% = 171
> 68% = 173
> 
> etc.
> 
> Greyscale step = ( 2.55 * percentage ) 
> 
> Best,
> Alex
> 
> --- In DigitalBlackandWhiteThePrint@y..., "frankg_photo" 
<frank@f...> wrote:
> >>
> > But the sep tablet i printed is in 0-100% points - so how do I 
find 
> > the flat points - how to convert them to the input and then 
output 

> > number(58/59%, 67/68%, 78/79%, 85/86%, 87/88%, 92/93%) ?
> > 
> > Hope I'm making sense ?
> > frankg