Our image files are huge files. Since you will normally be working with a smaller area, you will want to crop the larger image so that you have a much smaller file to work with.  This is easily handled using the Crop2 extension.  This handy extension was created by Kenneth McVay (it does not come with ArcView - to obtain this extension, see instructions below). We have placed this extension on all our computers in Sutton Lab.  The Crop2 extension not only crops the .tiff file, but it also creates a new .tfw file (world file) which contains the coordinate information for the tiff file.

To Use the Crop2 Extension:

1. Once in ArcView, choose File-Extension, scroll to find Crop2 and check mark it.  Press OK.  A new icon appears on your View menu.
2. Add to the view the image you want to crop, and make sure it is the active theme (by clicking on its name in the legend editor). (Remember, in the Add Theme dialog box, to add an image you must choose for your Data Source Types: the image data source option, not feature data source).
3. Make sure as always to set your view properties - map units. For the Austin black and white orthophotos, this is feet; for the color-infrared DOQ's (digital orthophoto quarterquads) off the CD's this is meters.
4. Click on the Crop2 icon, then drag a box on the image to define the area for cropping. You will be prompted with the File - Save dialog box. Navigate to the directory to which you want to save the new image file and give the new file a name.
5. Creating the new image can take several minutes - be patient! When the process is finished a message will appear saying the image was successfully created.
6. The end result is a new .tiff file and a new .tfw file. Remember, to use an image as an underlying theme for other themes, the .tfw file is critical - it contains the coordinates for the tiff image, so don't lose it or delete it.

Note: you will get error messages if you try to crop outside the limits of the original image theme, or if you try to crop from more than one adjoining image theme at once.  You will also get an error message if the image theme is not the active theme.

To display the new image:

1. Add the new image as a theme to your view.
2. Often the clipped image does not have the correct colors when you first add it. If the new image is from one of our Austin regional orthophotos that are in black and white, but it shows up as strange colors, double-click on the orthophoto's name in the legend. This brings up the Image Legend Editor. Click on the Colormap button.  On the next dialog box, click on the Gray button, then press Apply.  Sometimes the black and white orthophotos try to display as color photos, and this process tells them to go back to gray scale.  The orthophoto should appear as a legible photo now.
3. To make the orthophoto show up below the other themes, click on its name in the Legend Editor and drag it to the bottom of the list.

To Obtain the Crop2 Extension:
The Crop2 extension is available from ESRI's User Scripts download web site. After you get there, click on ArcView 3.x.  This will bring you to a long list of extensions in alphabetical order. Look for Image CropMiser version 2 by Kenneth McVay (Mr. McVay has created a number of useful extensions that he makes available for free through this ESRI web site). Be sure to read the "readme" document that comes up when you unzip it. It has directions for where to place the files within the ESRI directory structure.

11 September 1999
The School of Architecture at UT Austin
Comments to: Barbara Parmenter