Other image processing programs are mentioned, along with references. Section 1 closes with a challenge to the individual(s) working through this Tutorial: to take an "Exam" that tests your mastery of some of the concepts developed in the Introduction and this section.

A considerable number of image processing systems and programs are now on the market, i.e., are commercial products. Perhaps the most widely used software packages are supplied by ERDAS, Inc. of Atlanta, GA. A visit to the ERDAS Web Site (ERDAS is now part of Leica Geosystems) can help you to appreciate these sophisticated systems. At that site, there are online Tutorials on Remote Sensing, and on their MapComposer and IMAGINE processing software which are very much worth time to work through. You will need to register and get a password, and indicate whether you would like to be placed on their mailing list. To help you envision what the systems look like on a computer screen, we have reproduced three examples below (check the captions for details).

Enough! If you have reached this point by working through this entire Section and reasoned along with us in examining and analyzing the various Morro Bay images, you have become well-schooled in the basics of image interpretation. You are ready, as curiosity prompts you, to examine the processed images in the next Section - which starts with a geological study of a prominent fold structure in Utah - as well as many of the images in other Sections that have been processed to show outputs similar to those with which we have just become familiar. In most such cases, the interpretation has been done for you (as placed in the text) but the knowledge gained from Section 1 will aid you in better appreciating the information content in such images - perhaps to the extent that you can extract more from them than is stated in the text.

WAIT! If you are actually in a classroom (or are pretending to be) as you access this Tutorial on the Net or on the CD-ROM, you know the "curse" to expect after completing the first major block of information. An Exam!. (It's not much harder to complete than the Exam that followed the Overview.) We have devised a rather comprehensive set of questions based on image interpretations that we now invite (urge) you to undertake, in order to prove to yourself that you have evolved into a full-fledged expert in analyzing remote sensing data. We have reproduced a goodly number of scenes and computer maps that cover a single full Landsat MSS scene, which is in south-central Pennsylvania centered on the state capital, Harrisburg. (These have been taken from the Landsat Tutorial Workbook.) All the relevant questions and illustrations have been put on the special add-on page. These have their own answer sheet, accessed in the usual way. This, and a final Exam at the end of Section 21, will be the ultimate Q & A challenge we toss at you in this Tutorial. Rise to it. Press "here" - we dare you!!

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For further background, information, and reading underlying Principles of Computer Processing, with emphasis on Remote Sensing, consult:

Avery, T.E and G.L. Berlin, Fundamentals of Remote Sensing and Airphoto Interpretation, Ch. 15, Digital Image Processing, 1992, Macmillan Publ. Co.

Condit, C.D. and P.S. Chavez, Jr., Basic Concepts of Computerized Digital Image Processing for Geologists, 1979, U.S. Geol. Surv. Bull. 1462, Wash. D.C.

Jensen, J.R., Introductory Digital Image Processing, 2nd Ed., 1996, Prentice-Hall, Inc.

Xiuping Jia, Remote Sensing Digital Image Analysis, 1999, Springer-Verlag

Lillesand, T.M. and R.W. Kiefer, Remote Sensing and Image Interpretation, Ch. 7, Digital Image Processing, 2000, J. Wiley and Sons, Inc.

Moik, J.G., Digital Processing of Remotely Sensed Images, 1980, NASA Special Paper 432, U.S. Govt. Printing Office.

Russ, J.C., The Image Processing Handbook, 1995, CRC Press.

Sabins, F.F., Remote Sensing: Principles and Interpretation, Ch. 7, Digital Image Processing, 1997, W.H. Freeman & Co.

Special Issue on Image Processing, 1990, Photogrammetric Engineering and Remote Sensing, v. 56, no. 1.

Swain, P.H. and S.M. Davis, Remote Sensing - The Quantitative Approach, 1978. McGraw-Hill Book Co.