Creating Images

Creating Images with Software

Mathematica
Maple
gnuplot
other plotting programs
paint programs
- Adobe Illustrator
- xfig
- etc
custom software

Capturing Images from the Screen

Unix
The ImageMagick program import lets you capture window from the screen into a file. Give the command
```
import -frame file.gif
```
to capture a single window into the file file.gif. The cursor will turn to a crosshair, and you then click on the window you want to save. Be sure the window is not obscured by other windows. Omit the -frame option if you don't want the window frame (border and titlebar) saved.
To capture the entire screen, use the command
```
import -window root file.gif
```
Note that import is rather slow; it may take a minute or so to do its thing.
On SGI workstations there is a program called snapshot which you can use to capture a region of the screen which you select with the mouse. See its man page for details.
Windows
There are many programs for PCs which let you grab a region of the screen; some of them are listed in the software list for this course.
Macintosh
On a Mac you can press Command-Shift-3 which will take a snapshot of the entire screen and place it in a PICT file on the hard drive (or desktop). You can then open that PICT file in GIFConverter to crop out a particular region and/or convert it to a different file format, such as GIF.

Creating Images from Other Images

Downloading Images from the Web

One way to get images for a Web page is to steal them from another Web page. (Obviously you should only do this if you have the permission of the page's author.)

When viewing a Web page which contains an image with Netscape, you can put the mouse cursor over the image and press the right mouse button to bring up a menu which will let you save the image to a file. Other browsers may have similar options.

You can also fetch an image by specifying its URL directly, for example http://www.geom.umn.edu/pix/welcome.gif.

(This method works for fetching background images as well; use the View Source option of your browser to look at the html source for the document to discover the file pathname of the background image.)

Using a Scanner

A scanner is a device which scans physical images from paper to produce digital image files. A huge variety of scanners are available on the market today, ranging in price from a few hundred dollars to many thousands.

The Geometry Center has a scanner attached to a Macintosh; ask a staff member if you are interested in using it.

Next: Manipulating Images
Up: Still Images
Prev: Basics of Images

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Comments to: webmaster@geom.umn.edu
Created: May 31 1996 --- Last modified: Sun Jun 2 20:32:24 1996