Moving the slider to the right tilts the horizon on the right side upwards, while moving it to the left tilts the image in the opposite direction.


Sometimes an otherwise perfect digital photo contains a minor flaw that can be easily corrected in editing software. The most commonly found problems include unsightly red eyes in flash shots, skin blemishes and dust spots that produce highly-visible dark marks. All these problems are easily corrected.

However, editing tools can also be used to help you produce the kinds of pictures you want by correcting other minor deficiencies. We’ll look at some of the situations in which they can be used in this article.

As noted in Filters and Effects, although many of these adjustments are provided in digital cameras, it’s better to do them with editing software. For starters, you have more control over the adjustments. Secondly, because they are done on a copy of the image, if you don’t like the result, it’s easy to return to your original image file and start again.

Red-eye Correction
We’ll begin this article with a look at red-eye correction, which has become highly (and successfully) automated in almost all image editors. Picasa provides a good example of how basic editors handle red-eye correction. The redeye correction function is one of the Basic Fixes.


Red-eye correction is one of Picasa’s Basic Fixes.

Clicking on the Red-eye button allows the software to find and re-colour the affected areas and displays a dialog box that lets you Preview, Reset, Cancel or Apply the automatic correction.


Red-eye correction in Picasa.

Similar facilities are provided in more advanced editors. In The GIMP, red-eye correction is located by clicking on Filters > Enhance >Red Eye Removal.


Selecting red-eye removal in The GIMP.
This opens a dialog box with a preview window that lets you enlarge the section of the image you wish the software to work on. You can also set the threshold level for the target areas; the higher the level the larger the area of colour replacement and the more diffuse its borders. For difficult images, manual selection of the eyes is available.


The GIMP’s red-eye correction function.

Click on OK when you’re happy with the display in the preview window and the software will do the rest.

Cloning Tools
Cloning involves copying part of an image and ‘pasting’ it somewhere else in the picture. The cloning tool is indicated by a ‘rubber stamp’ icon, which shows how this tool works. Cloning is mainly used in association with other editing processes so we’ll show some examples here.

Using Photoshop Elements, we select the Cloning tool from the sidebar and set an appropriately-sized ‘brush’ to work with. As we work, we will change the size of this brush, the opacity of the cloning and its edge sharpness several times.


In this image an out-of-focus leaf spoils the shot composition. This will be removed with the cloning tool.

The first step is to enlarge the image by clicking on the magnifying glass icon until the area we wish to work on fills most of the workspace. Then we look for an area in the image that can be used to ‘paint over’ the unwanted fuzzy leaf.


Brush and opacity adjustments.

Moving the cursor over the area we want to clone we press the Alt button on the computer keyboard and left-click the mouse button. This ‘picks up’ the area under the cursor. We now move the cursor over the leaf area we wish to replace and ‘paint’ over it. The green leaf is replaced with red stamens.

In a job like this you will need to change the selection area several times in order to maintain a natural appearance. Be prepared to adjust the Opacity of the brush as you work. The higher the percentage in the Opacity box, the greater the degree to which the area to be cloned out will be replaced with the new selection. A 100% Opacity means total replacement.


‘Painting’ over an unwanted area with another area selected with the clone tool.

You can also adjust the edge softness of the brush to suit your needs, choosing a ‘hard-edged’ brush when precision is required and a ‘fuzzy’ brush when you want gentle blending. If at any time you don’t like the look of the area you have changed, simply click on Edit and select Undo Clone Stamp. This will take you back to the last change you made.


Undoing an unsatisfactory adjustment.

With practice, your skills in selecting the right replacement areas, brush widths and softness and opacity levels will improve. Be prepared to spend time trying all these settings out in order to be able to achieve a result like the example shown below.


The cloned image with the unsightly leaf removed.

Healing Tools
Healing tools resemble cloning tools; both let you correct small imperfections by replacing part of an image. However, whereas the cloning tool is a simple replacement tool, the healing tools also blend in the replacement area by matching the colours, tones and textures in the receiving area.

Most of the more sophisticated editors provide two Healing brushes. The standard Healing Brush tool works like the cloning tool, requiring you to select the area in the image you wish to sample before copying it into the area you wish to replace.


Two options for the Healing Tool.
Always work on one blemish at a time. Start by enlarging the image until the blemish is clearly visible. Then select an appropriate brush by right-clicking with your mouse.


Healing brush selection.
You can adjust the diameter, hardness, spacing and roundness of the brush in this dialog box. Start with a relatively soft brush with the slider between 50% and 70% so the edges blend in effectively. If you aren’t happy with the result, simply click on Edit and select Undo and try different settings.

Place the cursor on the area you wish to sample (in this case, the blue sky) and press the Alt button on the computer keyboard. Then move the cursor to ‘paint over’ the blemish. A close examination of the image below will show the replacement area is slightly lighter than the adjacent blue sky. This is because the sampling brush has picked up some of the tones of the clouds. Increasing the Hardness of the brush will reduce the area that is sampled and help to prevent this from happening.


Removing the blemish from the sky with the Healing brush.

Make the sampling brush smaller and softer and sample one of the areas of cloud. Use this sample to paint over the dark mark in the cloud area. Then look for other areas you can sample to remove what remains of the blemish. You will probably need to work on the area several times, changing brush size, hardness and spacing until the blemish has disappeared.


Sampling an area of cloud to ‘heal’ the blemish in that part of the image.

With the Spot Healing tool, there’s no need to specify a sampling spot. Simply move the cursor to the area you wish to correct and the brush will automatically sample the surrounding area, allowing you to paint over the blemish and replace it. This tool works best on small areas so always start with a small, soft-edged brush.


Use a small, soft-edged brush for removing blemishes with the Spot Healing tool.


The above image with most blemished ‘healed’. The white circle shows the size of the Spot Healing brush.

Straightening Images
Most photographers take the occasional shot with a sloping horizon so it should come as no surprise to find straightening tools in many image editors. All straightening tools will crop the image so some of your picture will inevitably be lost. Some will crop arbitrarily but most will retain the image’s original aspect ratio.

Some applications let you adjust the size of the crop and this can be useful if there are uninteresting areas you would like to exclude. However, there’s not much you can do if the interesting areas are likely to be cut off when the image is straightened – although, once you’ve become proficient at cloning, it’s often possible to clone in areas of sky or grassy foregrounds, as long as they aren’t very big.


Sloping horizons can spoil many digital photos.

In Picasa, the Straighten tool is one of the Basic Fixes. Clicking on the Straighten button applies a grid overlay to the image and displays a slider along the lower edge with two buttons: Apply and Cancel.


Before and after pictures (above) showing how the Straighten tool in Picasa is used. The tilt adjustment slider is circled in red in the left hand picture.

Moving the slider to the right tilts the horizon on the right side upwards, while moving it to the left tilts the image in the opposite direction.

The overlaid grid lines provide a guide to when the horizon is level. When you’re happy with the adjustment, click on the Apply button.

In Photoshop Elements, a button on the sidebar (circled in red) accesses the Straighten tool. To straighten the entire image, select Rotate All Layers, and then choose an option from the Canvas Options menu (circled on the top toolbar).


Straightening an image in Photoshop Elements.


To align the image horizontally, draw a line in the image to represent the new straight horizontal edge.


To align the image vertically, hold down Ctrl and draw a line to represent the new straight vertical edge.


Finally, crop the image with the cropping tool.
Three options are provided:
Grow or Shrink Canvas To Fit.
This setting resizes the canvas to fit the rotated image but the straightened image will contain areas of blank background. No pixels are clipped in this option.
Trim Background.
This setting crops the image to remove any blank background area that becomes visible after straightening. Some pixels will be clipped.
Crop to Original Size.
This setting keeps the canvas the same size as the original image. The straightened image will include areas of blank background and some pixels will be clipped.

Visit the following websites for free software downloads and/or additional information on the topic covered in this chapter: for background information on the Clone tool. for information on using the Clone tool in The GIMP. for a detailed tutorial on using the Healing brush. for a short tutorial on the Spot Healing brush. for a brief tutorial on the Straighten tool (using older versions of Picasa and Photoshop Elements but still relevant to current versions).

This is an excerpt from Post Capture Pocket Guide.
Click here for more details on this and other titles in the Pocket Guide series.


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