On Oct 28, 8:04 pm, Shawn Hirn <s...@[EMAIL PROTECTED]
> wrote:
> In article <1193476062.095758.49...@[EMAIL PROTECTED]
>,
> The Translucent Amoebae <transamoe...@[EMAIL PROTECTED]
> wrote:
>
> > So--
> > in the iphoto's application, there is an edit feature,
> > And within that:
> > Brightness, Contrast, Exposure
> > and Levels.
> > i think i have a good idea of what Brightness, Contrast & even
> > Exposure are/do...
> > But Levels completely baffles me.
> > i've looked and compared the graph to the pictures and i can not see
> > any correlation whatsoever...!!!
> > What is that representing...???
> > What does the x & y axis' represent...???
>
> > Thanx!
>
> Open up a very contrasty photo where there's a lot of light and dark
> areas, then fiddle with the settings under levels such as exposure.
> Notice that as you change the exposure and other controls, the histogram
> in the levels window changes. If you move the end points in the levels
> area to the point where the histogram begins, then adjust the middle
> point, you can bring out a lot of detail in the photo.
i think about them this way...
Brightness seems to increase/decrease the whiteness of all pixels
uniformly
Contrast seems to make dark pixels darker, and light pixels lighter
Exposure is more complicated;
When you lighten a picture, the light pixels get lighter, but the dark
pixels remain pretty much the same darkness. This occurs along a
curve, so the dark pixels are effected, but not by as much.
likewise, when you darken a picture with Exposure, the dark pixels get
darker, and the light pixels remain pretty much the same.
i do use the Levels controls, and i've noticed that when the spikes
are clumped together in the middle, and i slide the dark or light
towards the mountains, it seems to bring out detail by enhancing
surface texture with local contrast...???
But i STILL don't SEE what the mountains are supposed to be
representing...
Obviously; it's a graph of somekind, and as such, the x & y axis must
represent SOMETHING...???
But i just don't see what...???
thanx...???
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