Activity 2: Digital Scanning

The activity aims to replicate a hand-drawn plot using numerical values from digitally scanning it. The following figure shows the scanned hand-drawn plot provided for me by Justine Carpio. Also, according to her, the plot came from an undergrad thesis entitled Characterization of a UV pre-ionized TEA CO2 laser, by Marlon Rosendo H. Daza, dated September 1989.

Figure1. Scanned hand-drawn plot 

I opened this image using Paint; then from here I obtained numerical values of pixel coordinates for a range of tick marks in the plot.

Table 1. Tabulated data of tick marks with their corresponding pixel coordinate.

Using the built in function in Excel that shows the equation of the line for a graph, i obtained an equation relating the axes and the tick marks values for both x and y.

Figure 2. Graph of values from table 1 with the corresponding linear equation/relation for x axis

y = 0.0031x - 1.2031

Figure 3. Graph of values from table 1 with the corresponding linear equation/relation for y axis

y = -0.0009x + 2.7061

Now that we have the relation of the axis tick marks to the pixel coordinates. The next step is to sample the plot for its pixel coordinates, and use the equation to obtain the correct ratio of the plot. The following shows the tabulated results for the sampling of pixel coordinates of the plot, as well as its conversion using the two equations above.

Table 2. Sampling of pixel coordinates of the plot with their corresponding conversions.

I sampled this many, which is around 40 points, so that the plot can can also replicate the exact curves of the original plot.

Without further editing, the plot of the converted values of x and y can be shown by the following figure

Figure 4. Excel plot of the converted values of x and y from Table 2.

Visually, we can already say that the plot is almost the same as the scanned hand-drawn plot. To further observe the correctness of this method, we superimpose Figure 4. to a cropped image of the plot. Note that the axes are also superimposed. 

Now surely, we can say that produced output by using the method of digital scanning is an effective way of reproducing plots or images as well as reproducing values. As for the activity, i can rate the reproduced plot 10/10 for it really matched well with the original plot.

Accordingly, using the self evaluation guide, I think i deserve to have a grade of 5 for technical correctness as i was able to understood the lesson completely as well as produce all required output on time. And another 5 for quality of presentation given that all my graphs and images are properly labeled, captioned and of good quality. Also, from the handout itself, it says that being able to superimpose the original and the output would give you 1 bonus point. 

Thus, a total of 11 points.

I would like to thank Ate Bastine for giving me a scanned plot and especially for helping me create my  very FIRST blogsite , :)) Again, Thanks!