Imagine the Universe!
Imagine Home  |   Teachers' Corner | HERA Overview  |  

Imaging Tool - Changing the Scale of the Image

Changing the Scale of the Image
  • Changing the scale of the image adjusts the way that the data is displayed. This will cause slight variations in the visibility of items in the image, thus allowing you to see more or less. There are four scales you can choose from:
    • Linear: A method of displaying the data with graduated increments of the same size.
    • Logarithmic Scale: A method of displaying data (in powers of ten) to yield maximum range while keeping resolution at the low end of the scale.
    • Square Root: This method performs contrast manipulation using a Square-root transfer-function. It first normalizes the Histogram for the image. The resulting image is transformed by replacing each pixel value by another value using a table. The table has the shape of a square-root curve. It will compress the displayed brightness at the bright end of the scale, while expanding those at the dark end.
    • Histo-equalized: Histogram equalization (Histo-Equalized) scales the image data so that each bin contains roughly the same number of pixels.
  • With an image open, go to the "colors" button at the top of the window.
    1. Scroll down and you will see the choices as shown below:

      List of choices.
    2. Choose the type of scale that you want the image to have and click the diamond to the left.
    3. When selected the diamond will highlight in red.
    4. The image will instantly change and stay in that scale until you change it to a different scale.

Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

DVD Table of Contents
Educator's Index