The original image (right) of Portland Bill in Dorset was taken on a bright autumn day with good lighting conditions, but has some minor faults:

- the horizon is sloping towards the left hand side of the photo because the camera was not held straight at the point of capture.
- the overall tonality is rather flat and lacking contrast, with shadow areas too bright.
- finally, the foreground area would look better cropped slightly to emphasise the more interesting sea, lighthouse and sky areas of the photo.

All these faults can be corrected easily with PhotoImpact, as seen by the final edited image (below).

1-Adjusting a sloping horizon

A sloping horizon can be corrected with the Transform Tool (indicated with cursor pointer below), which can be used for a variety of amendments including perspective, distort and slant.

To adjust sloping horizons in landscape photos, a quick method is the Rotate With A Horizontal Line 0ption (see highlighted Rotate Method icon in image right). When this method is selected, a horizontal line appears in the centre of the image. Use the computer mouse to move the line to the desired location and angle by clicking on and dragging the end points of the horizontal line. When in position, double click the mouse and PhotoImpact rotates the image to the same angle as the line. Its best to make adjustments like Transform in one go to minimise loss of image quality arising from multiple attempts to complete the task. If your first attempt is incorrect, cancel it (right mouse click>Undo) and do the adjustment again after changing the number in the Rotate By Degree setting.

Adjusting a sloping horizon - Alternative Method

Sloping horizons can also be straightened using the Rotate By Degree method. Enter the estimated number of degrees in the box (see right) that the image needs to be rotated, then click the left or right rotate icon and PhotoImpact rotates the image accordingly.

When using the Rotate by Degree method, its often helpful to switch on Gridlines (select View on the Standard Toolbar, then Grid). This displays a set of vertical and horizontal lines over the image which can be used to visually assess if your adjustment is correct. If necessary, Gridline spacing, colour and display type can be adjusted (click File> Preferences>General>Guidelines and Grid, then alter the settings).

2-Using The Crop Tool

The Crop Tool is used for changing the size or shape of an image, in this example, fine tuning the image composition by removing some of the foreground area. After selecting the Crop Tool (highlighted left), drag the mouse across the image to select the cropped size. The area shown in red (see below) will be cropped. Use the mouse to move and fine tune the cropping area handles into the preferred positions, then click inside the cropping lines to perform the action.

The colour and transparency of the 'shielded' area can be changed if preferred. For example, if your photo is predominantly red, you could change the colour of the shielded area to green, or some other colour that contrasts well with your photo. To change shield colour, click the coloured square (see below) on the Crop Tool attribute bar and select a suitable colour from the dialog box that opens.

3-Adjusting Highlights, Midtones and Shadows

The final stage in this tutorial involves adjustments using Levels. This tool enables amendments to three tonal parts of an image, namely highlights, midtones and shadow areas. When the Levels dialog box is opened (select Format>Levels) a histogram is shown which displays the distribution of tones in an image as a 256 step greyscale from pure black to pure white (see dialog box below).

The horizontal greyscale (Input Level) is used to adjust contrast by moving the black point and white point sliders, while the grey point slider adjusts midtones. If the histogram display falls away before reaching the black and white point sliders, move the sliders in towards the edge of the histogram to reset the images black and white points.

In the example shown right, the black point has been changed from 0 (zero) to 5, which is a little lighter than solid black, while the white point has been changed from 255 (pure white) to 245. The greypoint slider has also been changed, from a value of 1 to 0.84 to darken midtone areas. Moving the greypoint slider towards the white point slider darkens midtones, while moving it to the black point slider lightens midtones. If the Preview check box is clicked, any adjustments made will show in the thumbnail image in the dialog box. Alternatively, you can preview the effect on your full size image by clicking the Preview button on the dialog box.

In addition to adjusting highlights, midtones and shadows on the Master channel, Levels adjustments can also be made to the Red, Green and Blue (RGB) image channels. The general procedure is the same as adjusting the Master channel. First select the channel you wish to adust from the pull down Channel menu, then move the sliders as required. Adjusting both the Master and RGB channels usually produces an image that has a good tonal range without any obvious colour cast.

Many photos will produce a histogram similar in shape to the one shown above, but some photographs, usually referred to as 'high key' (comprising mainly light tones) and 'low key' (comprising mainly dark tones) will have a very different distribution. The Levels Tool can still be used to adjust these types of images where required though.

The vertical greyscale (Output Level) is used to adjust overall brightness, but for many images this can usually be left at the default settings. This also works on a 256 step greyscale, but has just two sliders instead of three.

The Levels Tool also has two 'auto' options (Stretch and Equalise) which can be used to adjust image tones. These can be tried to see if they give quick fixes, but you will probably get better results by adjusting sliders as discussed above.

Note : Although Levels was only introduced with version 8 of PhotoImpact, the same effects can be produced with the Tone Map Tool which also features in PhotoImpact 6 and 7. Tone Map is actually a more powerful and versatile tool, but Levels is simpler to use and has a more user friendly interface than Tone Map.