Re: Asking again about Auto Levels in CS2

"Norm Dresner" <ndrez@[EMAIL PROTECTED]
> wrote in message 
news:QV%Uj.311402$cQ1.106061@[EMAIL PROTECTED]
>I asked a few months ago about the difference between manually doing
Levels
> and using the Auto Levels command because when the program does it
> automatically there are no holes in the histogram and whenever I did it
> manually I got a lot of spikes with spaces around them.  At the time I
was
> told -- and it sounded convincing -- that the program does it
individually
> on each of the channels separately and then merges the result which 
> produces
> a continuous histogram.
>
> WELL ... I've tried doing it channel-by-channel (R/G/B) manually about a
> dozen times now and I still get a combined RGB histogram that shows many
> missing levels, much as it did when I just leveled the whole image.
>
> SO ... I'm asking again:  what does the program do when applying Auto 
> Levels
> that results in a continuous histogram that can't be duplicated
manually?
> Does it intentionally spread out the levels so that there are no holes?
>
>    TIA
>        Norm


I wouldn't worry about this. Pixels will be removed (and added) regardless

whether you use the auto setting or do it manually. It makes little 
difference to the final output. However; what you should not do is to 
re-adjust the image several times as each time you do so compounds the
loss 
of pixels. It doesn't matter whether you use Levels or Curves; pixel loss
is 
inevitable. If you get the exposure right in the first place...

PDM