# Effective pixel size calibration

This folder contains the images used to calibrate the effective size of a pixel in the images of the Drift experiment. The images are of USAF resolution targets.

For this analysis we use a package we developed called `micat`. The version of `micat` used for this analysis is archived in the libraries folder.  
*NOTE* a command line arguments `-g` and `-e` are used to manually identify groups

At the time of the experiment the file:  
`usaf_drift_image.jpg`  
was taken. When analysed my `micat` the 6 is identified as a set of horizontal bars.

The image  
`usaf_drift_image_edit.jpg`  
is the same image as `usaf_drift_image.jpg` but a line has been drawn through the 6 to stop it being picked up by `micat`.  
All visible elements belong to group 4  
This gives a result of  2.227 um per pixel.

The same objective and camera settings were used at a later date to collect an image of the same USAF target at a more centred location to improve calibration and to verify which group the elements were in. This image is  
`usaf_drift_10_times_objective.jpg`  
This gives a result of 2.201 um per pixel. This value was used for analysis.