Use Generate Test Data to create a variety of test images that may be useful for demonstrating or testing ENVI features. These include constant value images, horizontal and vertical ramps, random number images using both uniform and normal distributions, and images generated using a Gaussian Point Spread function.

  1. From the Toolbox, select Raster Management > Generate Test Data. The Generate Image Parameters dialog appears.
  2. Select the output image type from the Output Image Value drop-down list:
    • Constant: Generates an image with a constant value for every pixel. Enter the desired DN value in the Value text box.
    • Horiz Ramp or Vert Ramp: Generates an image with either a horizontal or vertical linear ramp. Enter the desired minimum and maximum ramp values in the Min Value and Max Value fields.
    • Random (uniform) or Random (normal): Random (normal) returns an image with normally-distributed random numbers. Random (uniform) returns an image with uniformly-distributed random numbers. Enter the minimum and maximum values to occur in the image in Min Value and Max Value fields. Enter a Seed value to initialize the random number generator. If you do not enter a seed value, ENVI uses the system clock for initialization.
    • Gaussian PSF: Generates a Gaussian image. Enter the minimum and maximum values to occur in the number of output Samples, Lines, and Bands in the corresponding fields.
  3. Select the Output Data Type from the drop-down list.
  4. Select output to File or Memory.
  5. Click OK. A status box appears while the image is being processed. ENVI adds the new image to the Layer Manager when processing is complete.