The re are some common editing processes that are done to images of all kinds regardless of whether they are intended for the web or for print publication. The color, contrast, and brightness of an image may need to be adjusted. Photographic images of people and animals often require Ared eye reduction. @ When only a small portion of an image is needed, the image needs to be Acropped@. This involves selecting and saving a rectangular portion of the image. Images scanned from books or journals often require that the margins be cropped since they usually contains no useful information. Large collections that are being processed for use on the web may require the same repetitive tasks to be done to thousands of files in what is known as batch processing.
Because of enormous competition in the imaging software industry, publishers are constantly adding new features to their programs, so in a very short period of time programs can change dramatically. However , it is worthwhile to look at some categories that exist at the end of the year 2000. Many criteria mentioned can also be used to review other image-processing software.
Professional image-processing programs that have a wide range of features are commonly used in office settings, and as their prices drop, are becoming more popular. These professional image-processing programs can easily perform all of the basic processes such as cropping, resizing, and color correction, as well as more advanced processes such as the use of image layers, which go beyond the scope of this paper. Because of intense competition among software publishers in recent years, many of the less expensive products (under 50 dollars) have added features that were once only available on high-end packages.
For the purpose of this paper, some rough separators between the software intended for professionals and those intended for home use is that the professional software tends to have many more image-processing tools, support more file types, and provide high end features such as layering and digital water-marking. Another feature that is available in most of the professional programs is the ability to use pressure sensitive Wacom tablets. Also the icons that represent the tools provided in these professional packages are often arranged in densely packed toolbars. This provides more speed and power, but is a harder to learn than imaging software for home use, which offer a less dense layout without so many icons to memorize. Also, imaging packages for home use often have Awizards, @ which help a user to accomplish a particular task in a simple (slow) step-by-step fashion. Low-end image-processing packages intended for home use will not be covered in this paper.
Adobe Photoshop is the most well known of the professional image-processing programs, and many of its competitors are trying to add all of the features of Photoshop to their products. Photoshop grew out of the (paper) publishing industry, and is widely used today in the preparation of images for print publications and for the Web. Photoshop=s competitors try to match it=s features and to be compatible with Photoshop Plug-ins. These Plug-ins are small programs, which are added to Photoshop to increase its functionality. An important new feature of Photoshop 6 and of some of its competitors is the ability to create and edit vector graphics that was, until recently, only the domain of drawing programs such as CorelDraw.
Some of Photoshop抯= better known competitors include Corel PhotoPaint, PaintShop Pro, and Live Picture. These programs are all available at a lower cost than Photoshop, and PhotoPaint comes bundled with the well-know vector graphics program, CorelDraw. Some of them such as PaintShop Pro seem to emulate the interface of Photoshop. Another notable features of PaintShop Pro is its ability to open very rapidly. When only a single image needs to be quickly cropped or resized, this ability to open the program quickly, complete your work, and be done, is appreciated. PaintShop Pro has image-management features that will be discussed in more detail later.
Macintosh and Windows computers can both run Photoshop, but Unix/Linux computers cannot. A popular image-processing program in the Unix/Linux world for several years, and recently available for Windows, is the (free) open-source program, AThe Gimp, @ often referred to as a Photoshop clone. Besides its Photoshop-like interface, and numerous features, the Gimp has a powerful scripting language that allows very sophisticated batch processing. Other well-known image-processing tools in the UNIX world are xv, and Image Magick, but these lack the power and refinement of the Gimp. The CorelDraw Suite, which includes CorelDraw and PhotoPaint, is now available for Linux.
Imaging software intended almost exclusively for web development has become popular in recent years. The most well known of these programs include Macromedia Fireworks, Adobe ImageReady, Ulead PhotoImpact, and Ulead Web Razor. Any of the professional all purpose packages, such as Photoshop, can be used to do tasks such as optimizing files for the web by reducing their pixel depth; however many users have found these programs dedicated to preparing files for the web to be particularly effective at these tasks.
Batch processing, the ability to perform repetitive tasks on a group of files, is a very important function of imaging programs. Many programs have this feature, including Adobe Photoshop which has the ability to record processing steps which are performed on an image using a tool called AActions@. These steps are saved and can be performed on a single image or a batch. Corel PhotoPaint and several other professional programs have this feature. Equilibrium software=s DeBabelizer Pro is a well-known program for Mac and Windows, specializing in batch processing. DeBabelizer has a graphical interface, but also uses scripting.
In the Unix/Linux environment, the Gimp provides batch processing ability through the use of AScript-Fu, @ a full-featured scripting language geared toward programmers. An older tool that works well with only a command line interface, NetPBM, is an open source toolkit, consisting of 180 separate small programs. Used primarily for the conversion of images between a huge variety of different formats, NetPBM also allows some basic image operations such as resizing, and changes in pixel depth. This toolkit allows users with only a very basic knowledge of Unix and little or no programming experience to perform powerful batch processing from a command line.
Specialized 搒titching” programs are used to automatically stitch together smaller images that have some overlap in order to create a large image. These programs can stitch together images horizontally to create panoramas, and some can stitch together images arranged vertically and horizontally. They include QuickStitch, Photovista, and Visual Stitcher. Canon PhotoStitch can stitch together images to create a 360-degree panorama that is rotated with a java applet. Some all-purpose image-processing programs, including MGI PhotoSuite, also contain stitching features.
Another specialized program, PhotoGenetics is a unique Aimage adjustment@ program which has become popular among professional and amateur digital photographers.
ATo improve an image using PhotoGenetics, a person rates the original against variations produced by the software. Simply by clicking on a scaled bar, the preferred enhancements transfer to the original image. When the user is satisfied with the results, the new image is saved. The set of enhancements may also be saved separately and applied quickly to similar images in the future.” (QBeo, Inc., 2000)