Digital BW, The Print

Take any image, cut the resolution by some factor, resampling with 
nearest neighbor interpolation (so you retain actual image data), and 
compare histogram to original, then cut it again... and so on and so 
on...  You will see that the histogram remains unchanged for a good 
number of progressive subsamples.  You could make a whole statistical 
study of why this works if you chose to:)  Of course an arbritary 
section would not be an actual sample of the entire image and would 
probably not be representative of the image as a whole...

Yes, the histogram is a great visualization tool for understanding 
your image... no arguement there:)

mark

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "J Michael 
Sullivan" <michael@h...> wrote:
> Not sure what you mean by a small subsample. If you mean an 
arbitrary section of an 
> image, then I can assure you many of your images are being edited 
under a false 
> pretense!
> 
> The premise of a histogram is to demonstrate the prevalance of data 
distribution in 
> an image. The begin and end points are what most people focus on, 
but they are only 
> one small aspect of the usefulness of a histogram. It is VERY 
useful to look at an 
> image and "see" that it is mostly high-key, or low-key, or mid-key, 
or evenly 
> distributed. Having such knowledge is important as to which is the 
best method (and 
> there are many) to enhance the most critical image detail, as there 
is no way that 
> EVERY pixel can be important -- to me this is the key of good 
scanning. 
> 
> MJS
> (author of "Make Your Scanner a Great Design and Production Tool", 
now out of print)
> 
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Mark Hahn" 
> <markhahn2000@y...> wrote:
> > I'm not sure that Adobe does it, but from my tests only a small 
sub-
> > sample of an image is all that is really needed for a accurate 
> > Histogram... the big question is how useful is it really?  I 
mean, 
> > are you really not going to apply the specific curve to an image 
> > which makes it *right* because you don't like the look of the 
> > histogram?
> > 
> > mark
> > 
> > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "J Michael 
> > Sullivan" <michael@h...> wrote:
> > > I'm sure the Adobe dudes figured out a way to optimize it for 
the 
> > G5 chip too :(
> > > 
> > > No matter, moving Gigabytes of 16bit layers is gonna require 
one 
> > kickass machine!
> > > 
> > > mjs
> > > 
> > > 
> > > 
> > > --- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Stephen 
> > Kobrin" 
> > > <skobrin@h...> wrote:
> > > > This question may be rendered moot in Photoshop CS as 
according 
> > to 
> > > > Evening's introduction you can have a "live historgram" 
running 
> > while 
> > > > you use curves.  As I understand it, you will be able to see 
the 
> > > > impact of any curves ajustment on the histogram in real time.
> > > > 
> > > > The bad news, at least for some of us, is that it looks like 
CS 
> > > > requires a Pentium III processor.  I have a II with plenty of 
> > memory 
> > > > that works just fine with PS 7.
> > > > 
> > > > Steve