Image-editing software has more creative potential than vector-drawing CAD software. Similarly, soft pencils are more expressive than hard pencils. Image-editing programmes have become widely understood because of the popularity of digital photography. They allow designers to adjust individual pixels or groups of pixels. A pixel is a picture-element: a single square of colour. High resolution images use large numbers of pixels and low resolution images use small numbers of pixels.
The best-known and most sophisticated image-editing programme is Adobe Photoshop. Its popularity has attracted software authors to produce a great range of filters which apply special effects to Photoshop images. These filters are popular with the graphic designers and photographers who use Photoshop as their primary software tool. Corel Photopaint is broadly equivalent to Photoshop in its functionality. It comes as part of the Corel Draw Suite of programmes and is well-integrated with its stablemates. Paintshop Pro is a lower-priced image editor. It has fewer functions but more than enough for gaden design purposes. GIMP is an open source shareware equivalent of Photoshop, still good with significantly fewer capabilities.
With Photoshop-type software, garden designers can work directly on images. It is an easy task to take a digital photograph of a garden and superimpose images of garden details borrowed from books and catalogues. And for people who are not accustomed to reading plans, Photoshop images give a legible 'artist's impression' of how the garden will look when the proposed design changes have been implemented. Photoshop-type software can also be used to work directly on air photographs, thus dispensing with the need for plan drawings.
Photoshop is the best-known image-editing software.