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PASSPORT TO THE SOLAR SYSTEM: Educators Imaging Lessons

Student Worksheet for Lesson C

Mars Mystery Spot:
Processing the image of Warrego Vallis

In this mini-lesson you will process the image of Warrego Vallis. This image came from the Viking Orbiter's Mission to Mars.

The information below is about the image you will be using:

Original Image file name=WV/MI40S092.IMG

  • Where WV stand for Warrego Vallis
  • M stands for the file identity. In this case tiles of a Global map of Mars called MDIMs ( Mars Digital Image Maps).
  • I is the resolution code for this image. This image has a resolution of (1/256 degrees per pixel) or (.231 kilometers per pixel)
  • 40S means this image is centered at 40 degrees south latitude.
  • 092 means this image is centered at 92 degrees west longitude.
  • IMG is the images graphic file type

NOTE- All longitudes on Mars are measured to the west,

  1. Launch NIH Image and open the image with file name Warrego.tif

  2. First, you are going to apply a different group of colors to the image of Warrego Vallis.tiff. Even though the colors are going to change, the luminosity values (v) will remain the same. You do this by changing the Look Up Table (LUT). Go to the menu called Options in the command line. Go down to the item called Color tables and drag over to the lateral menu. Go down to the item called Fire-1 and let go.

    You have just changed the Lookup Table (LUT) for one of your images. You can adjust the LUT with the LUT tool in the tools window. IT is the horizontal line with a vertical arrow sticking out top and bottom (directly above the upper case A in the NIH Image Tool Box. Click on this tool and move up and down in the LUT window, noting the changes.

  3. To prove to yourself that luminosity values do not change when applying different LUTs (groups of colors), choose one pixel out of your image and write down its x,y (row and column) and pixel value.

    NOTE-remember to use the coordinate tool and the info table to get your data. You can also use the magnifying tool to make it easy to see one pixel at a time.

    Now go Options to gray scale and remeasure that exact pixel's luminosity. Write down the values.


  4. Another way to look for features of the Warrego Vallis is to process the image with the contrast and brightness Map. Like LUT changes, processing an images contrast and brightness map does not impact the images luminosity value. But using the Map makes previously hard to see features easy to see.

  5. Another way to look for features of the Warrego Vallis is to process the image with filters. Like LUT changes, filter processing an image does not impact the images luminosity value.

    NOTE- to apply a filter to just one part of your images, select that part with the rectangle tool. It is the tool to the right of the magnifying glass in the tools window and looks like a row of marching ants when applied)

    In the program NIH Image you process (filter) images from the "Process" menu. Experiment with filter options, getting a feel for what tools give your eyes the most information about the features known as Warrego Vallis. You can go to the Undo item in the Edit menu in the command line to undue the last action you took filtering the image.


  6. Now close the image, without saving any changes.

    Reopen the image again.

    Go to and select "Load Macros" in the "Special" Menu in the command line.

    Select "More Macros" from the Macro folder which should be in your NIH Image Folder.

    You now have a set of macros in the Special Menu in the command line. One of those macro selections in your Special menu is "ASCII Dump".

    Now select a portion of one image with the rectangle tool, that is about one millimeter square ( in other words just select a speck of the image with the rectangle tool). With the selection made, go to the "ASCII Dump" in the "Special" Menu and let go.

    Click once back on the image with your old selection still in place. Now filter it once from the process menu using the filter of you choice.

    Now redue the ASCII Dump and compare the number tables. Is there a difference?

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