Basic Editing

Cropping and resizing, brightness and contrast adjustments and some basic colour adjustments can be found in even the simplest image editing software. You will probably also find automated tools for correcting red eyes in flash shots and sharpening images. In this chapter we’ll look at how to use these tools and then move on to more sophisticated functions that can help everyday photographers to produce richer-looking prints from their digital photos.
If you’ve printed photos from a compact digicam at a photolab or on a snapshot printer, they will almost invariably have been cropped. When you make a borderless print, part of the image is cut off to make it fit onto the paper because the aspect ratio of the image doesn’t match that of the paper. If you were to print the entire image, there would be white bars on either side of it because the paper has a 3:2 aspect ratio, while the digital picture is 4:3.

However, aside from this largely unplanned (and uncontrollable) cropping, there are times when you might actually want to trim away unwanted portions of a digital photo. The tool for doing this is usually shown by an icon looking like a pair of scissors.

Aside from making borderless prints, other reasons you may wish to crop an image include:
1. Adjusting images to fit a particular frame;
2. Improving shot composition;
3. Straightening crooked horizons (or other horizontal elements); and
4. Focusing the viewer’s attention on what really matters in the picture.

The illustrations below provide an example of some reasons to crop images.

This full frame image from a DSLR camera has potential that can be realised with cropping.

Using the cropping tool, we can cut off a large part of the sky and also remove the out-of-focus foreground. Neither contributes much to the picture and both reduce its overall impact.

The end result is a much better composition that complements the subject.

Regardless of the reason for cropping, it’s important to be clear in your mind about exactly why the image must be cropped. This will help you to decide which areas to trim away and which to keep. Many photographers regard cropping as a technique that can make or break a photograph and put a great deal of effort into deciding what looks exactly right.

Start thinking about cropping when you take the picture because that will help you to minimise the amount of image data you discard. It’s better to move (or zoom) in closer to the subject and frame it tightly and keep your images at high resolution than to take the shot with the main subject surrounded by wasted space that must be cropped away. Consider the following when planning a crop:
1. Crop for interest. Focus on the subject that really matters and discard irrelevant distractions.
2. Crop for sharpness. Make sure the cropped area is really sharp before committing to the crop.
3. Crop for drama and impact. It’s OK to trim away large areas of detail-free sky and create a panorama that concentrates on the foreground and horizon.
4. When cropping to straighten skewed horizons, use the ‘arbitrary’ or ‘free’ rotation tool to turn the image until the horizon is level. Then apply cropping.
5. Don’t over-crop. Remember the more you trim away, the more pixels are discarded. Always be aware of the effect this can have on your ability to print the image.

Resizing
The main reason for resizing digital images is to share them with family members and friends, either via emails or on social websites like MySpace and Flickr. Some digital cameras will do this for you and save the images as separate files. But it’s just as easy to do the job with editing software.

Different viewing devices have different requirements for displaying images and these should be taken into account when choosing how small a resized image should be. The most popular sizes are as follows:

• 320 x 240 pixels (QVGA) for handheld devices like camera-phones;
• 640 x 480 pixels (VGA) for small, standard TV sets and older 4:3 computer monitors;
• 800 x 600 pixels for larger 4:3 monitors;
• 1024 x 768 pixels for high-resolution 4:3 monitors (also the maximum size for posting on social websites);
• 1280 x 720 pixels for widescreen TV sets with standard resolution;
• 1920 x 1080 for high-definition widescreen TV sets.

Irfanview is one of the best applications for resizing images as it provides a wide range of pre-set sizes plus the ability to resize batches of selected image files.
Brightness, Contrast and Colour Ad justments
There are often times when your digital photos may require a little fine-tuning in brightness, contrast or colour. All image editors provide these facilities but some provide a wider range than others.

Most adjustment tools are found in either the Enhance or Adjustment drop-down menus. Sliders are used by many editors and the image on the screen will change to reflect the changes you make.

The drop-down menu for image enhancements in Adobe Photoshop Elements.

Brightness and contrast slider adjustments in Adobe Photoshop Elements.

Cloning and Healing
Sometimes an image may contain elements you would like to remove but in positions that make them impossible to remove by cropping. In such cases, the cloning tool provides an easy fix. In most editing software, the cloning tool is indicated with a rubber stamp icon. It works by copying a selected area and repeating it in a new section of the image.

You can usually choose the size of the cloning ‘brush’ and determine whether it has hard or soft edges. Most software will also let you adjust the ‘strength’ of the copying so you can let the layer beneath the cloned area show through – if so desired.

The Healing Brush (which is often denoted by a Band-Aid icon) is used to correct imperfections in images. It works by sampling the colours and textures in the area around the blemish and blending the mark into the background. Some applications provide two settings: Healing and Spot Healing. With the former, you must select the area containing the hues and textures you wish to replicate. Spot healing makes the selection automatically, based on the area around the blemish.

In this illustration, we want to remove the head of the camel in the lower right corner of the picture. Overlaid on the image is the brush selection tool.

The selected area to be copied is circled in red.

Using the cloned area to ‘paint’ over the unwanted camel.

The unwanted camel is gone but the area from which it was removed remains visible as a blotch. This can be fixed with the Healing Brush.

Using the Spot Healing brush to ‘paint away’ the blemishes to leave even tones.

Sharpening
Most digital images can benefit from a little sharpening and all editors provide sharpening tools. The trick is to use the right amount. Oversharpening can produce unattractive artefacts, which show up as light, dark, or coloured outlines along edges in the image. Under- sharpening will leave images looking slightly soft.

The illustration above shows coloured artefact circled in red.

Enlarged previews allow you to control the degree of sharpness in the most crucial parts of the image.

The best sharpening tool is the Unsharp Masking filter, which is found in more powerful image editors. This tool applies sharpening by increasing contrast along the edges detected by the filter. It also provides a high degree of control over the sharpening process.

Noise Reduction
Another useful tool that must be applied with a light touch is noise reduction processing. It works by slightly blurring the image to subdue the grainy appearance of images with high noise levels. Unfortunately, if too much processing is applied, the image will become unsharp.

More capable image editors let you adjust the strength of the processing and provide sliders for controlling the amount of detail that is preserved and selectively correcting colour noise (which is more unattractive than normal pattern noise). Preview images are normally provided to show you how the image has been changed.

Noise reduction processing in Adobe’s Photoshop Elements editor. The preview window shows you the effect of the adjustments in the three parameters.

USEFUL URLs
The following websites provide additional information on the topics covered in this chapter.
www.photoreview.com.au/tips/editing/ for some useful tips on image editing.
http://en.wikipedia.org/wiki/Image_editing for an excellent overview of the processes involved in image editing.
http://en.wikipedia.org/wiki/Retouching for specific information on photo retouching.
This is an excerpt from Mastering Digital Photography Pocket Guide 2nd Edition.
Click here for more details on this and other titles in the Pocket Guide series.

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