Lab: Checkerboard Effect / Geometric Transformation II

[Exercises] [Workspace]

Purpose: This lab illustrates the concept of image resolution, and demonstrates the checkerboard effect caused by pixel replication.

Activities:

1. Experiment with the "checkerboard effect"
   1. Read and display any image.

      1. Glyphs:Input/Output:Data Files: User defined

   2. Perform sub-sampling on the image using the following operators:

      1. Glyphs:Data Manip:Size & Region Operators: Shrink

      2. Set the Shrink operator parameters so that the "Width" and "Height" factors are the same.
      3. Display this image

   3. Expand the sub-sampled or shrunken image via pixel replication. Apply the Expand operator:

      1. Glyphs:Data Manip:Size & Region Operators: Expand

      2. Set the Expand operator parameters so that the "Width" and "Height" factors are equal. The resultant image will be the same size as the original.
      3. Display the results. Notice that the new "pixels" are represented by a larger portion of the screen.

Exercises

1. Take the original image (with 256 grey-levels) and generate several images with different quantization levels: 64, 32, 16, 4, and 2. Use the operator Glyphs:Arithmetic:Two Operand Arithmetic: Divide.
2. What is preferable: higher spatial resolution or a higher number of quantization levels?

Khoros Workspace
Execute the visual program c2s10spatial-resolution.wk