In this tutorial (using PhotoImpact 11), 3 photographs of a church interior are used to produce an image with a wider HDR range than is possible from a single exposure of the same subject. The three start images are shown below, along with the HDR image produced from these. The darkest image was exposed for highlight areas such as detail in the main window, while the two remaining images were exposed for midtone and shadow areas. All 3 images were recorded with the camera on a tripod to ensure composition was identical in all cases. Exposure was adjusted using different speed settings with the aperture left unchanged, this ensured that 'depth of field' (parts of the image in focus) remained the same for each exposure.

HDR image left, original images above.

To use PhotoImpact's HDR tool, first open the images you wish to use. A minimum of 2 images are needed, but you should get better results if 3 or 4 are used. As mentioned above, images should ideally be taken with the camera on a tripod to ensure composition is identical in all cases. When the images are open, select High Dynamic Range from the Photo menu on the main toolbar (see right).

The HDR dialog box deals with three tasks, composition, optimization and operations. In the composition task (see screen below), simply select the camera brand used to take the photos, in this example, Canon, then click the button in the bottom right hand corner (circled red) to generate the HDR image.

If your camera brand does not appear in the drop down list, you can still use an option in the list to see the results. Alternatively, you can create your own camera curve profile by using 3 to 5 images and checking the 'auto generate camera curve' button instead. If this produces suitable output, you can save the profile for future use.

When creating your own profile, you need to specify the 'F stop' (aperture) interval used by the camera to take the images. If the images still retain their EXIF data (the digital cameras record of settings used, eg shutter speed, aperture) the F stop can be calculated automatically, otherwise this needs to be set manually in the dialog box. Typical examples could be half or one stop intervals between each images exposure. If you are unfamiliar with camera exposure settings, there are many introductory photography books available with information on this subject.

After creating the initial HDR image, further tonal adjustments can be done on the highlight, midtone and shadow areas within the Optimization screen (see below) by adjusting the appropriate sliders (note: the final HDR image can also be edited with PhotoImpact tools such as Levels or Curves if preferred).

The Operations stage allows basic editing tasks to be completed if required, namely rotating, resizing or cropping the image, although these tasks can also be completed with PhotoImpacts standard editing tools. If the Resize option is used to change the image dimensions, ensure the padlock (highlighted red, right) is checked to retain the images height and width ratio. When all tasks are complete, click OK to create the final HDR image and save to file.

A comparison of the HDR image with an edited version of one of the original images is shown below. The original image (shown left), exposed for mid tone areas, was edited using 'Curves', previously known as Tone Map in earlier versions of PhotoImpact. Although this image has produced a quite acceptable result, the tonal range and detail in the HDR image (shown right) is better.