Activity 1: Digital Scanning
The goal of the activity is to reconstruct a hand-written graph by extracting data from pixel values of the data points. For this activity, Will be extracting data from this graph:
The image is opened using Microsoft Paint and the pixel values are obtained by pointing the cursor over a pixel and it’s location is shown in lower-right portion of the status bar.
We first obtained some values to be used in the calibration of our pixel values, like location of the graph origin (bias x and bias y), and the scale of x and y pixel values to relate the pixel location with physical variables.
Bias along x: 56 pixels
Bias along y: 433 pixels
Scale of x: 80 pixel / 5 units (days)
Scale of y: 34 pixels / 10 units (% percent killed)
Origin: (56, 33)
Image size: (723, 505)
To obtain the reconstructed x values from the pixel values, we use the equation:
x = (raw_x – bias_x) / scale_x = (raw_x-56)*5/80
To obtain the reconstructed y values from the pixel values, we use the equation:
y = (bias_y – raw_y) / scale_y = (433 – raw_y)*10/34
Pixel values of data points were obtained, and the physical values were calculated.
We can see that there is good reconstruction of the data with almost all points in the original graph and the reconstructed graph coinciding with each other.
Rating: 10
Because there is almost perfect correspondence in the values of the reconstructed and original graph.
Acknowledgment: Benjamin Palmares
Graph from the journal Plant Physiology 1926
jagged tooth v2.1 
