Re: A column on white point

Dean Wilmot

Hi Dan 

Thanks very much mate

I’ll check my various books I have of yours :) 

BTW if you or anyone in the group has a good second hand drum for a howtek 4500 drum scanner please contact me if willing to sell, I’m letting everyone I know I’m interested as. It looks like mine is just starting to craze 😢

Kind regards 

Dean Wilmot

On 6 May 2020, at 02:37, Dan Margulis via <dmargulis@...> wrote:

On May 3, 2020, at 11:59 PM, Dean Wilmot via <deanwilmot@...> wrote:

Hi Dan,

Forgive me if this is a basic question esp for this group.

Where in your books does it talk about the best method for setting the black and white points? (for colour and especially B&W images) (and for adjusting mid-tones).

Im starting to use the Howtek 4500 drum scanner I bought last year alot more now and although I've been using a technique recommended by Image Science from the The Fundamentals of Digital e-Book ( section attached) I was wondering though if this is really the best method?

White point/black point is a subset of the discipline often called “color by the numbers”. Chapter 3 of Modern Photoshop Color Workflow covers this, as does any edition of Professional Photoshop; they all have chapters titled “Color by the Numbers”.

Both approaches try to analyze the image and use curves to eliminate anything that is found to be wrong. Assuming that there is in fact a “white” point and not something very light yet slightly colored, there are two steps: making sure that it is neutral, and making sure that it’s as light as possible consistent with retaining detail.

The traditional approach is to try to accomplish both with a single curve set, and this is what the PP chapters try for. In MCPW the first set of curves must set neutrality only. If convenient, they can also set lightness, but if not the final adjustment is made in LAB. But LAB is clumsy if the file arrives that is not neutrally correct.

Dan Margulis

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