Re: filmscanners: creating correction curves from scanned calibration chart?

["Maris V. Lidaka, Sr." <mlidaka@ameritech.net>]

If you're using PS, click on each the points in the image that you want to set, 
check the read numbers, then click, in the separate channels, on the curve at 
or about that point, they type in the read number in the input box and your 
desired output number in the output box.  Do this for each point you want to 
set and in each channel.

There may be a quicker way to set the input point on the line, maybe by 
double-clicking on the image spot, but I don't remember for sure.

Maris

----- Original Message ----- 
From: "michael shaffer" <rarewolf@roadrunner.nf.net>
To: <filmscanners@halftone.co.uk>
Sent: Sunday, November 11, 2001 7:59 AM
Subject: RE: filmscanners: creating correction curves from scanned calibration 
chart?

[snippped]

|   However, I'll probably satisfy myself having gray balanced (as Bruce
| Fraser implies ... "you're 95% there if the grays are accurate").  The more
| important question is still #2 ... "how do I do it?".
| 
| 
| shaf  :o)
| 
| 
| > >From: "michael shaffer" <rarewolf@roadrunner.nf.net>
| 
| > >gray_value == (0.18^(1/2.2))*255 = 117 .  Similarly,
| > >
| > >logD (18%) = .745 implies (1/(10^logD))^(1/2.2)*255 = 117
| 
| >(2)  What is the best way to create the curves?  For example,
| > I would like to use the target for the "curve's" gray eyedropper
| > to change the curve such that 115/118/116 becomes 117/117/117,
| > ... and for a different gray, 155/159/154 becomes 157/157/157
| > ... but the gray eyedropper doesn't seem to work this way(?)
| 
|  
|