Another- more technical nuisance, is images which lack contrast. It’s rather easy and common to be in a situation where the contrast of an image can be degraded. Shooting through a pane of glass, shooting into harsh lighting such as the sun, or shooting with use of the improper exposure are conditions which result in low contrast. What do I mean by contrast anyway? Contrast is the term that describes the distribution of lights and darks in an image. It turns out that lack of contrast in digital images can be considered a bit of a quirk in the technology. Digital sensors don’t yet compare to the contrast detection ability of our eyes, and so the way digital sensors try to manage this is by making metering decisions ( in auto mode) based on incoming light with respect to an 18% grey or “middle grey” neutral point. The calibration scheme attempts to expose a shot so that some of the light reflected by the subject is equivalent to middle grey, and so, the camera sensor has a tendency to push all colors toward 18% grey, no matter what they are. This means that white objects may not always appear true white, and black doesn’t always appear black, depending on the exposure, you get a middle grey tone instead of pure black or white. In a low contrast image, everything, all colors, get pushed toward middle grey. But the good news is that it can be helped by some techniques in post processing.

See the example illustrating the result after processing, and before.

After (top) Before (below)

This image was shot through an airplane window and at high altitude. There was natural atmospheric haziness competing with the opaque pane of fiberglass that I had to shoot through. You can see that everything seems to be turned a blue/greyish hue and lacks contrast as a result. It doesn’t reflect much of what my eyes saw.

This image can benefit from the use of two techniques, but one I haven’t yet brought up. Color correction (which I’ll discuss in the next post) was the first step to improving this image. Color correction is an easy process in Picasa or Adobe Lightroom- it involves selecting a different neutral tone in the scene than the one the camera used ( in its auto white balance wisdom) to achieve a better color separation and representation of the scene. It has the effect of increasing contrast, but only by so much.

Using the “Tuning” panel in Picasa, you can fix this photo using the “Neutarl Color Picker” eye dropper tool.

Before

After

You might notice a slightly warmer (from blue to yellow/red) color rendition after the neutral color picker tool is used, but the image still looks a bit hazy. Picasa has an auto-contrast button in the “Basic Fixes” tab which will drive more contrast into the image. I can’t tell you what it’s doing exactly, because it’s just a button tool. Press it and see this is what results.

Auto Contrast

I find the auto contrast adjustment a bit harsh and would probably go back to the Tuning panel to pull the shadow slider to the right to make the dark corners brighter.

Another example of Contrast being enhanced by post processing. Here i also decided to convert to black and white to enhance the structure detail of Manhattan buildings.

After (top) Before (below)

Contrast is one of the most helpful adjustments you can make to an image because it helps our eyes to identify and find features in the environment, and for that reason it often makes an image seem orders of magnitude better when it is increased. But don’t go crazy, less is sometimes more, and there are times when low contrast is an artistic desirable.

Color Correction – White balance

in detail next.