Italian Alps

A few weeks ago when discussing this aerial photograph of Corballis golf course, I mentioned how more often than not when an airplane is at its cruising height there isn’t much to see out the window apart from expanses of cloud.  An exception is when you happen to be flying over the Alps, on your way to Italy for a skiing holiday, as I was when I took today’s photograph.

My main reason for posting this shot today is that I want to use it to illustrate something that newcomers to digitial photography often don’t appreciate, and that is how important (and easy) it is to greatly improve your photographs with some very minor tweaks on the computer after you’ve taken the shots.

The image on the right is the same photograph, straight from the camera – which in this case was my Nikon D50, which is a perfectly capable entry-level digitial SLR.

If you look at this photograph versus the post-processed photograph above, you should see that the image above is a much better image, with greater clarity and, for want of a better word, punch.

The photograph that the camera produced is a bit washed out, lacking in contrast, and there is no pure white or pure black in the shot.

I can graphically show you this by showing you the histogram of the image.  A histogram is a visual representation of how many pixels of all the values between 0 and 255 are in the final image, and is the best way off assessing both exposure and contrast.

You can see the histogram for the photo straight out of the camera on the right.  In general in a histogram, if all the pixels are bunched to the left of the histogram, you have likely underexposed, while if they are bunched to the right of the histogram, you have likely overexposed.  If they are bunched around the middle, the exposure is probably good, but if there are gaps at the left and the right, the contrast is low.

Most images that come straight out of  a digital SLR camera will suffer from low contrast, due to an anti-aliasing filter which is put over the sensor for good reason, but which has the side effect of reducing the contrast.  There is very little you can do in-camera to improve contrast, which is why doing some very basic processing on the computer is a good idea to dramatically improve an image.

It is useful too that practically all digital SLRs have a mode to show you the histogram for an image immediately after you’ve taken it.  If you want to get more consistent results from your photography, review the histogram for a shot as well as the image itself on the LCD screen and you’ll find that more photographs are useable when you import them to your PC later.

The good news is to alter the histogram, and so correct contrast issues, is very straight forward using the likes of Photoshop Elements, iPhoto, Aperture, or even to some extent the free Picture Manager that comes bundled with Windows.

Depending on the software you have, the approach differs – if you can alter the “Levels” in the image you want to do this and you can re-map the pixels back to the full 0 to 255 range from the limited range of values indicated by the original histogram.  This is what I did for the image above in Aperture, with the improvement in the image you can see above.  The histogram for the post-processed image on the right hopefully makes a little sense too – you can see there are pixels across the full range now, meaning that somewhere in the final image there is pure white and pure black, which is always good as it makes for a more dynamic shot.

If there is no “Levels” adjustment supported in your software, look for a contrast adjustment and that will achieve much the same.  Failing that, or if you don’t want to get too technical, try an “Auto-correct” and you might be suprised at the results.

A lot of people spend money on a good digital camera, especially the entry level SLRs, and never touch the photographs that are produced.  This is a real shame, and it’s important to realize that adjusting images in this way is easy, and is not (as you might be tempted to think) “cheating”.  In the days of film, the developing process in the darkroom included the same types of adjustments using flashing and other techniques – it is far easier in the digital world with software that is easy to get and easy to use.  I often get told “your photos are so clear” – well one of the main reasons for this is not that I am a better photographer or have a better camera, it is because I spend a minute or two improving them on my laptop – in fact essentially I develop them, just digitally.

If you too take photos with a digital camera, be it an SLR or a compact, give this basic post-processing step a go with one and I guarantee you’ll be pleasantly surprised.