White Balance

Every time a digital camera takes a picture
it needs to establish the white point as the basis from which the percentage of each color is derived. Because this is affected by the quality of light in a scene, most cameras offer adjustable white balance settings. In auto mode, complex algorithms in the camera decide where the white point is. This is usually fairly accurate, though under cloudy conditions it may cause blue-tinged images.

Some digicams also offer a manual setting in which the user has to decide what is the exact white point. A small rectangular piece of white card can serve as a reference and you can adjust white balance by using this.

Sharpening & Softening

In conventional photography an image is either sharp or unsharp. There is not much that can be done about that. In digital photography however, there are several options to make an image sharper or softer by enhancing or blurring edge detail to make boundaries between darker and lighter image tones more or less prominent.
Raw images produced by digicams often have a certain softness to them.

Some digital cameras then apply a built-in sharpening function, often to counteract the effects of interpolation.
As the adjustment of in-camera sharpness levels is usually rather limited, jaggies or artifacts can become more visible. It is better to leave sharpening until after adjustment in your digital darkroom. Unsharp Mask is the tool to use, since this allows the most precise adjustment levels and has a wide variation of parameters to produce the exact effect you need. Failing this, using the in-camera function would be your only option.

Not every subject will need an equal amount of sharpening and some subjects are best left a bit soft. Female portraits will usually benefit from slight softening to make their facial features more flattering. Also if you want to blend your image into a background or paste them into another image, it is best to soften edges a little to make their borders less prominent so that joints between parts of an image become invisible.

Noise reduction techniques

Digital images can be prone to noise due to the visual effects of electronic errors of the camera's sensor. Long exposures, higher ISO settings or higher temperatures can introduce noise, while some color channels – notably the blue channel - will be more affected by noise than others. This is because sensors are often less sensitive to blue light, and to compensate for this the blue channel is amplified more than others. JPEG compression can also amplify noise.

To reduce or remove noise, some companies produce (Photoshop) plug-in filters, while a few digicams feature built-in noise reduction methods.
Here is a technique to reduce noise caused by long exposures of 2 seconds or more,
which can manifest itself as fixed colored dots often denoted as stuck pixels.
These can be successfully removed by taking a “dark frame” before or after the main shot, with the same shutter speed as the main exposure, and subtracting this from the original to replace the stuck pixels.
Open the two images in Photoshop and paste the dark image as a second layer. Apply a little Gaussian Blur and change Layer Options to “Difference”. You will note that most stuck pixels are now invisible and the image has improved considerably.

Image stabilization

Camerashake is one of the major reasons for unsharp images. Not every photographer can hold a camera steady at slower shutter speeds. Therefore try to follow the rule of choosing a shutter speed equivalent to the lens' focal length. Slower speeds may lead to camera movement and consequently unsharp images.
For some time now manufacturers of zoom lenses and telephotos have been offering a feature called image stabilization on their more expensive lenses or high-end binoculars.

Canon was the first to introduce the system on their 300mm IS-lenses while Nikon followed suit with their VR-types.
Image stabilization helps to steady the image projected back into the camera by using floating optical elements, which serve to compensate for vibration caused by the user.
The system features gyro sensors which correct jerky hand movements that would normally lead to camera shake. It is claimed that handhold shots are possible at shutter speeds 2 stops slower than with the system turned off.
The system has been available in digital video cameras with large zooms for quite some time now and has proved to be very effective. Only recently manufacturers of digtal still cameras have also started featuring image stabilization. Notably Sony and Olympus have incorporated it in some of their models and other manufacturers may well follow.