| Spandex Rutabaga 2006-06-08, 7:39 pm |
| "Joëlle" wrote:
> Try Levels instead, I use it when I want more contrast. It doesn't always
> suit, but works on your image.
"It doesn't always suit" is not just an artistic judgment. It has
to do with the content of your image. You have to be careful. The
way you are doing this, i.e. sliding the left slider way over to 53,
destroys all the differences in brightness of all the pixels in the
range 0 to 53. That's around 20% of possible brightness levels. In
a dark image that's a catastrophe. It's possible to do this if your
image is all pastels and there are no dark colors in the image since
then there are no colors about whose brightness differences you have
to worry. This is such a pastel image and the Histo1 attachment
shows it contains nothing in the brightness range 0 to 133.
It is much less dangerous to do what you do with the Low Clip Limit
in Histogram Adjustment, which shows you the fraction of pixels in
your image that will be affected. If it's over about 0.05% the
losses will be quite perceptible. When an image isn't empty of
dark values you need to do this a little differently as shown in
Histo2. Increase contrast by expanding midtones more and more. This
increases the proportion of dark and light colors at the expense of
medium colors. To tweak the overall impression of brightness use
the Gamma control. Less than one darkens and more than one lightens.
You can see that even on a pastel image this can be an alternative
to messing with the Low Clip Limit in Histogram Adjustment or in
Levels.
If you don't like Histogram Adjustment use Curves instead. Put
three points along the diagonal, one at the quarter scale point,
one at the midpoint, and one at the three-quarter point. Move
the quarter point down and the three-quarter point up to increase
contrast. Additionally slide all three points to the right to
darken the image overall (as shown) or to the left to lighten it.
You will probably have noticed some differences between Histogram
Adjustment and Curves. Curves appears to over-saturate and HA
appears to under-saturate. What you like and how much you compensate
later is a matter of taste. I suspect that Smart Fix has some of
the characteristics of Curves. The Automatic Saturation Enhancement
and Hue/Saturation/Lightness filters can be used to tweak saturation.
In PSP X, Smart Fix has a Saturation slider. I've no idea if the
Saturation control in Fill Flash (PSP X) will change things if you
try to use it at a Strength of zero.
Whatever you use I strongly recommend looking at a histogram to
see if you are destroying color differences. A follow-up post shows
you what to look for.
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