Reeves, S.J. “A Survey of Image Processing Software and Image Databases” Digital Signal Processing Handbook Ed. Vijay K. Madisetti and Douglas B. Williams Boca Raton: CRC Press LLC, 1999 c 1999byCRCPressLLC 58 A Survey of Image Processing Software and Image Databases 58.1 Image Processing Software General Image Utilities • Specialized Image Utilities • Pro- gramming/Analysis Environments Stanley J. Reeves 58.2 Image Databases Auburn University Images by Form Image processing has moved into the mainstream, not only of the engineering world, but of society in general. Personal computers are now capable of handling large graphics and images with ease, and fast networks and modems transfer images in a fraction of the time required just a few years ago. Image manipulation software is a common item on PCs, and CD-ROMs filled with images and multimedia databases are standard fare in the realm of electronic publishing. Furthermore, the development of areas such as data compression, neural networks and pattern recognition, computer vision, and multimedia systems have all contributed to the use of and interest in image processing. Likewise, the growth of image processing as an engineering discipline has fueled interest in these other areas. As a result of this symbiotic growth, image processing has increasingly become a standard tool in the repertoire of the engineer. Because of the popularity of image processing, a large array of tools has emerged for accomplishing various image processing tasks. In addition, a variety of image databases has been created to address the needs of various specialty areas. In this article, we will survey some of the tools available for accomplishing basic image processing tasks and indicate where they may be obtained. Furthermore, we will describe and provide pointers to some of the most generally useful images and image databases. The goal is to identify a basic collection of images and software that will be of use to the nonspecialist. It should also be of use to the specialist who needs a general tool in an area outside his or her specialty. 58.1 Image Processing Software Image processing has become such a broad area that it is sometimes difficult to distinguish what might be considered an image processing package from other software systems. The boundaries among the areas of computer graphics, data visualization, and image processing have become blurred. Furthermore, to discuss or even to list all the image processing software available would require many pages and would not be particularly useful to the nonspecialist. Therefore, we emphasize a representative set of image processing software packages that embody core capabilities in scientific image processing applications. Core capabilities, in our view, include the following: c 1999 by CRC Press LLC • Image utilities: These include display, manipulation, and file conversion. Images come in such a variety of formats that a package for converting images from one format to another is essential. Furthermore, basic display and manipulation (cropping, rotating, etc.) are essential for almost any image processing task. The ability to edit images using cut-and-paste, draw, and annotate operations is also useful in many cases. • Image filtering and transformation: These are necessary capabilities for most scientific applications of image processing. Convolution, median filtering, FFTs, morphological operations, scaling, and other image functions form the core of many scientific image processing algorithms. • Image compression: Anyone who works with images long enough will learn that they require a large amount of storage space. A number of standard image compression utilities are available for storing images in compressed form and for retrieving compressed images from image databases. • Image analysis: Scientific image processing applications often have the goal of deriving information from an image. Simple image analysis tools such as edge detection and segmentation are powerful methods for gleaning important visual information. • Programming and data analysis environment: While many image processing packages have a wide variety of functions, a whole new level of utility and flexibility arises when the image processing functions are built around a programming and/or data analysis en- vironment. Programming environments allow for tailoring image processing techniques to the specific task, developing new algorithms, and interfacing image processing tasks with other scientific data analysis and numerical computational techniques. Other capabilities include higher-level object recognition and other computer vision tasks, visual- ization and rendering techniques, computed imaging such as medical image reconstruction, and morphing and other special effects of the digital darkroom and the film industry. These areas require highly specialized software and/or very specialized skills to apply the methods and are not likely to be part of the image processing world of the nonspecialist. The packages to be discussed here encompass as a group all of the core image processing capabilities mentioned above. Because these packages offer such a wide variety and mix of functions, they defy simple categorization. We have chosen to group the packages into three categories: general image utilities, specialized utilities, and programming/analysis environments. Keep in mind, however, that the distinctions among these groups is blurry at best. We have chosen to emphasize packages that are freely distributable and available on the Internet because these can be obtained and used with a minimum of expense and hassle. 58.1.1 General Image Utilities netpbm pbmplus is a set of tools that allows the user to convert to and from a large number of common image formats. The package has its own intermediate formats so that the conversion routines can be written to convert to or from one of these formats. The user can then convert to and from any combination of formats by going through one of the intermediate formats. Functions are also provided to convert from different color resolutions, such as from color to grayscale. Several other functions do basic image manipulation such as cropping, rotating, and smoothing. The source is available from ftp://ftp.wustl.edu/graphics/graphics/packages/NetPBM/. c 1999 by CRC Press LLC xv xv is an X11 utility that combines several important image handling functions. It can display images in a wide variety of display formats, including binary, 8-bit, and 24-bit. It allows the user to manipulate the colormap both in RGB and HSV space. It crops, resizes, smooths, rotates, detects edges, and produces other special effects. In addition, it reads and writes a large variety of image formats, so it can serve as a format conversion utility. Until recently, xv has been freely distributable. The latest version, however, is shareware and requires a small fee to become a registered user. The source is available from http://www.trilon.com/xv. NCSA Image NCSA Image is available in versions for the Mac, DOS, and Unix (X11). The Unix version is called ximage. ximage allows the user to display color images. It can also display the actual data in the form of a spreadsheet. A number of other display options are available. Like xv, it allows for manipulation of the colormap in a variety of ways. In addition, the user may display multiple images as an animated sequence, either from disk or server memory. The functionality of NCSA Image is augmented by other programs available from NCSA, including DataSlice for visualization tasks and Reformat for converting image formats. The source is available from NCSA by ftp at ftp://ftp.ncsa.uiuc.edu/Visualization/Image/. ImageMagick ImageMagick is an X11 package for display and interactive image manipulation. It reads and writes a large number of standard formats, does standard operations such as cropping and rotating as well as more specialized editing operations such as cutting, pasting, color filling, annotating, and drawing. Separate utilities are provided for grabbing images from a display, for converting, combining, resizing, blurring, adding borders, and doing many other operations. The source is available by ftp from ftp://ftp.x.org/contrib/applications/ImageMagick/. NIH Image NIH Image is available only in a Macintosh version. However, the popularity of NIH Image among Mac users and the breadth of features justify inclusion of the package in this survey. It reads/writes a small number of image formats, acquires images using compatible frame grabbers, and displays. It allows image manipulation such as flipping, rotating, and resizing; and editing such as drawing and annotating. It has a number of built-in enhancement and filtering functions: contrast enhancement, smoothing, sharpening, median filtering, and convolution. It supports a number of analysis operations such as edge detection and measurement of area, mean, centroid, and perimeter of user-defined regions of interest. It also performs automated particle analysis. In addition, the user can animate a set of images. NIH Image has a Pascal-like macro capability and the ability to add precompiled plug-in modules. The source is available from NIH by ftp at ftp://zippy.nimh.nih.gov/pub/nih-image/. LaboImage LaboImage is an X11 package for mouse- and menu-driven interactive image processing. It reads/writes a special format as well as Sun raster format and displays grayscale and RGB and provides dithering. Basic filtering operations are possible, as well as enhancement tasks such as background subtraction and histogram equalization. It computes various measures such as histograms, image statistics, and image power. Region outlining and object counting can be done as well. Images can c 1999 by CRC Press LLC be modified interactively at the pixel level, and an expert system is available for region segmentation. LaboImage has a macro capability for combining operations. LaboImage can be obtained from http://cuiwww.unige.ch/ftp/sgaico/research/geneve/vision/labo.html. Paint Shop Pro Paint Shop Pro is a Windows-based package for creating, displaying, and manipulating images. It has a large number of image editing features, including painting, photo retouching, and color en- hancement.