You've asked on other threads for thoughts on post processing. I thought this image made a good opportunity to talk about contrast. I hope that's ok...
You have a nice shot here, but the image looks a little flat. Here are the levels in the photo and it's immediately apparent as to why:
Note the curve of the level histogram. At first glance, it's a nice "bell curve" and while it has some clipping, it's not bad. Let's take a closer look at the histogram, but first let me explain the mechanics of this graph first in case we have some readers that aren't familiar with it at all.
Levels Histogram Mechanics
Some pixels, like those in the bright areas of the water are almost pure white. Other pixels like those in the shadows near the water's edge are almost pure black. We could assign the amount of brightness in each pixel a number...from 0 (for totally black) to 255 (for totally white). So, a pixel in the shadow has a value of 0, while a pixel in the bright area of the water has a value of 255.
Even though the photo is color, you could imagine each pixel has having a brightness... not just those that look black and white. For example, much of the green in this photo is roughly in the middle of our brightness range. We could say it's around 127 in terms of the value scale. Some greens are brighter (closer to 255) than the exact middle and some are darker (closer to 0). If you look at the photo's overall brightness you should be able to see that more of the green is toward black than white. The brightness values in the center of the scale are called "midtones".
The height of each point along the histogram represents the number of pixels that have that brightness level. So, we can see that at the far right, very little of the photo is pure white. In the middle, we can see that a lot of the photo is midtone. At the far left, we can see that there is some black in the photo.
Closer Look at the Histogram
Here, I've added labels for what the histogram is telling us about the photograph.
Now, let's consider again what a "bell curve" means. It means that the majority of the pixels in the photograph are midtones...in other words, despite being varied in color, the majority of the photograph has very little difference in brightness.
In other words, the image lacks contrast!
Increasing Contrast
There are many ways to increase contrast but the two most common are to use Levels or Curves.
Think of "Levels" as the ability to slide the graph to the right or left. You can push everything toward white to brighten the image. You can push everything toward black to make it darker. You can push on the midtones to focus your darker or lighter goals there. Ultimately levels doesn't change the shape of the histogram dramatically. Instead, it just "smooshes" or "stretches" it. Don't get me wrong here. Levels is a useful tool. Not every photo needs a dramatic change in contrast!
Think of "Curves" as the ability to remap any area of the histogram to another. We could take the range of "20 - 40" and make it "200 - 220" if we wanted. That would take dark areas of the photo and make them very bright. Not that that's a good thing, but the point is, curves can "smoosh", "stretch" or "remap" any part of the curve. Since it adds the ability to remap specific points, the histogram can look very different once it's done.
Back to the Photo!
Here is what I got after playing a bit with the Levels and Curves tools, I made all of my adjustments visually -- there is no ideal shape to the histogram curve that you should try to create. I also added more contrast to the scene than might be considered ideal since I wanted to emphasize contrast for this discussion.
Summary
There are three points I'd like to leave you with out of this entire post. If you remember nothing else other than these things, you'll be far ahead of most shooters. If your camera will display a histogram for you as you take each shot and you remember these points, you'll be even further ahead!
1) A "pile" of pixels at the extreme left or right edge is bad unless you have a lot of pure black or pure white in your scene.
2) A "pile" of pixels in the center with very little of the curve reaching either edge is generally an indication that the scene lacks contrast. Not always a bad thing -- and the good news is, this is an easy thing to fix in post.
3) Beyond that, there's no ideal shape to the histogram. It's all scene-dependent.
Anyway, that was a lot to type. This took me nearly an hour...hopefully, it's helped someone!
Small Creek by the Roadside
