Re: [Gimp-user] how to darken bright areas

[Gene Heskett <gheskett shentel net>]

On Wednesday 04 January 2017 21:02:15 paulhurm wrote:

> > I do have a bit of this already done. I do have each photograph as
> > individual scans, both with and without the captions and I am not too
> > worried right now about the final "reassembly". My current desire is
> > just to get the issue resolved with the quality of the prints. I
> > already have ideas about "reassembly" but not worrying about this
> > step until I get better quality images.
> >
> > As mentioned, I had a few steps accomplished once before but can't
> > remember what I had done. I still seem to recall having used an addin
> > somehow and playing around with luminance so that comment by you
> > helps validate some of my current thinking.
> >
> > I think my next step might have to be to try to go through the
> > various lists of addins to see if I can find one that might help or
> > perhaps stumble upon what I used before.
> >
> > I'm way too green to develop my own filter as you suggested above
> > although the concept you described seems good. I kind of had that
> > accomplished in the previous attempt where I did get the desired
> > areas separated onto a separate layer. It's just that I now have no
> > idea what I did to get to that point. Thus my post hoping for
> > suggestions!!
> >
> > Thanks.
> >
> > Paul
>
> Gene,
>
> And...
>
> I just went back out and read a bit about RGB vs CMYK. I have never
> gotten far enough along with graphics programs to have had to worry
> about this but obviously now I do. As a former physics teacher I have
> been exposed to RGB much more than CMYK.
>
> Just one more topic I have to go out to learn!!!
>
> Paul

Chuckle...  Make the connection with RGB in the video realm, where its 
all additive. So much red, so much green, and so much blue is white.  
Hence its RGB. In the video realm, its basically a matter of ajusting 
each colors gain once black is established, to get a pleasing white on 
the video screen. THis is RGB.

OTOH, The print realm is all subtractive, the Cyan reflecting green and 
blue but absorbing red,, the Magenta reflecting red and blue but 
absorbing green, the yellow reflecting red and green while absorbing 
blue, and K is the combined luminance expressed as the density, hence 
the CMYK designation.

One, RGB references just barely visible as black, while CMYK references 
the base color of the whiteish paper as its white, and inks are laid 
down to subtract the RGB from the white.  And often, to save the 
expensive colored inks, the blackest areas will get a reduced amount of 
color in favor of getting a more consistent black by useing black to 
build the density needed with far less ink.

Neither method can at the end of the day, represent the complete color 
spectrum the human eye (with good color vision) can see, but generally 
can be tweaked to do a decent job in the center 2/3rds of that color 
chart we've all seen in the past few decades.

Thats not all of it, but thats about as simplicated as I can make it. I 
hope this helps.

Cheers, Gene Heskett
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