Steps taken in Idrisi32 after file imported and converted to raster image
Step 6. I used the GIS Analysis > Database query > RECLASS tool to convert the image to only three values (1,2,3) and developed a legend.
Step 7. In order to calculate the area of each element, I estimated resolution by measuring pixels in the road at three places across the original image. This single-pass oil field service road should accommodate one dual-wheeled service truck. Such roads are usually about 3 meters wide. There were an average of 45 pixels across the road. Thus each pixel represented approximately 0.067 meters. I opened the metadata file for the reclassified image and changed resolution to 0.067 m. Then I ran GIS Analysis > Database Query > AREA (tabular). This produced a text file which listed the respective areas in square meters as: water 4,024 m2 , cattails 3,047 m2 and uplands 1,548 m2.
Step 8. I changed the color code with symbol workshop and produced a map with a title, legend, north arrow and listing of respective areas. I saved it as a map composition file and a bitmap.