Activity 1 - Digital Scanning

Our very first activity is all about reconstructing a hand-drawn graph from an old journal found in the College of Science (CS) library through digital scanning. Ratio and proportion is implemented for the reconstruction where the number of pixels for the scanned image is converted to the physical value of the plot.

Initially for the first day of classes (June 16, 2009 - Tuesday), all of us went to the CS library where . Here, I found a hand-drawn graph from a 1953 Botany journal which is about analysis of plant environment. Below is shown the scanned image.


On our second meeting (June 18, 2009 - Thursday), we started the reconstruction of the hand-drawn plot. Using the software Nero PhotoSnap Viewer Essentials, I cropped my image leaving only the graph so that the pixel locations will coincide directly with the reconstruction's physical values. I also adjusted the angle of its orientation so that error in reconstruction will be minimized. The following image is the cropped image of the graph.


I opened the cropped image using the software Microsoft Paint where I located the pixel locations (both X and Y) of my selected data along the plot, which appear at the lower right corner of its working window when the mouse pointer is directed to them. Then, I noted these pixel locations together with determining conversion factors which will turn pixel locations into the physical values of the plot. Since the pixel location of the origin in Paint is at the upper leftmost part, I subtracted the Y pixel location from the total vertical pixels of my cropped image.

In equations:
Light Intensity = X*(1000/318)
Count per Limit Time = Y prime*(200/219) ; where Y prime = 769 - Y

Thus, for the horizontal axis, there is 1000 units of Light Intensity in 318 pixels while there is 200 units of Count per Limit Time in 219 pixels for the vertical axis.

Next, using the software OpenOffice.org Calc, I tabulated my 14 data points and their corresponding physical values.


Finally, I have reconstructed the hand-drawn graph by plotting the physical values in the same program. Below is shown my reconstructed graph which has background of the cropped image.


Notice that there is quite some vertical displacement at high Light Intensity values and this is because the hand-drawn graph is not equally scaled especially in the Y direction. Meaning, there are significant differences in pixels between two ticks of Count per Limit Time. As an illustration, there are 219 pixels between 0 and 200 units of Count per Limit Time which served as my conversion factor for all data points in Y, but there are only 207 pixels between the ticks of 200 and 400 units of Count per Limit Time in the hand-drawn graph. However, since I fully understood and enjoyed the whole process of this activity plus my reconstruction of the hand-drawn graph is successful, I confidently grade myself 10/10.

This activity is completed with the help of Dr. Gay Jane Perez for scanning our images. In addition, Raffy, Ed, and Gary guided me with the techniques in plotting, scaling, and making an external image as background of a plot in OpenOffice.org Calc.