NIH Image Basics

This page is a good place to start if you are a first-time NIH Image user. Click here to skip this page and go right into the image processing tutorial.

What is NIH Image?

NIH Image is an image processing program developed by Wayne Rasband at the National Institutes of Health. It was developed to look at medical images, but we'll use it to look at images of Mars taken by the Viking Orbiter spacecrafts.

The Basic Tools

Here's a typical screen shot of NIH Image in action. There are five windows shown here.

• The color look-up table (LUT) shows what colors are or shades of gray are used in your image.
• The TOOLS window lets you pick different tools, like a magnifying glass to zoom in on a feature.
• The MAP window lets you change the brightness and contrast of your image. It's really handy for bringing out detail in washed-out images.
• The INFO window gives you a readout as you move the mouse over an image. It shows the pixel value, its location, and some other stuff as well.
• The image window (Valles Marineris in this case - a big canyon on Mars) shows an image that you've opened. You can have several images open at once.

Some things to try

1. Open an image

We've put an image file (called "Mars1.tif") in the same directory as NIH Image. It's an image of Valles Marineris, a canyon on Mars that would stretch across the continetal United States! Choose Open from the File menu and se lect the "Mars1.tif" file.

2. Change the contrast - bring out some detail

We'll use the MAP window to change the brightness and contrast. It's pretty easy - just slide the brightness and contrast controls and watch your image change!

What do the Tools do? Use Balloon Help to find out

On Macintosh systems you can turn on balloon help. Just pull down the balloon help menu from the yellow question mark in the upper right corner of the menu bar.

Now you'll get pop-up balloons when you move the mouse over a tool.

Try using the magnifying glass to expand a crater.

Next... the NIH Image Tutorial

Our NIH Image Tutorial shows you how to open Viking images of Mars (they're in a special format), how to measure distances on the planet, and lots more. Click here to go to the NIH Image Tutorial.