A1 - Digital Scanning

Introduction
In this activity, we use ratio and proportion to find the numerical values of a digitally scanned hand-drawn plot. For now you will need the following software, Paint for finding the pixel locations of points on the graph, and Excel or OpenOffice Spreadsheet to tabluate the values of the graph.

Activity
1. Find and old journal in the CS Library and look for a hand-drawn graph from its pages. Make sure there is only one plot on the graph. Photocopy the graph.
2. Digitally scan the graph in grayscale. Except for this setting, choose your own resolution. Save the file in any standard image format such as jpg.
3. Open the image in Paint and move the mouse on the tick marks of both X and Y axis of the graph. Note down the physical values of the tick marks and through ratio and proportion, find how many pixels along the X and Y is equivalent to the physical values on each axis. Note also the image pixel location of the graph's origin.
4. Move your mouse about points on the graph. In Paint, you see these numbers at the bottom right of the application window. Tabulate in Excel or Spreadsheet their pixel locations.
5. Find an equation to relate pixel location to physical variable and use this to interpolate points on the graph.
6. Reconstruct the graph in Excel or Spreadsheet.
7. Compare the scanned graph with the reconstructed graph and rate yourself in a scale of 1 to 10 on how you accurately you were able to reconstruct the graph. (Note to Spreadsheet users, do you know that you can overlay an image on the background of your Spreadsheet graph? Bonus points to those who can find how this is done.)