Pseudocolor Applications

Building the Cantata Workspace

1. Read and display the image $DIP/data/retina.viff using operators User defined and Display Image.
2. Insert a ramp grey scale on the image.
   1. Use operator Piecewise Linear to generate a 10 x 128 grey-level downward ramp.
   2. Use operator Flip so that the ramp has increasing values from bottom to top.
   3. Use operator Convert Type to make the values unsigned byte.
   4. Use operator Pad to create a border of width 1 pixel and value 255 around the grey-scale image.
   5. Use operator Inset to overlay the ramp scale on the original image.
   6. Display the resultant image.
3. Use the Autocolor operator to pseudocolor the image. Note that Autocolor adds a map to the image file and that the pixel contents displayed under the mouse in the Display Image operator show each pixel as an index. In this manner, although the image has been pseudocolored, the pixel index still contains the original grey value.

Exercises

• Experiment with the different colortables. Some will enhance certain features more than others.
• The SA-Pseudo colortable was published in Scientific American. What is its main feature?