- To measure the values of a column or bar chart accurately, you need an image that is as big as possible. I usually make a physical printout of a stretched chart image on an A4 paper.
- Measure the bars/columns in millimeters
- Decide the real value for your biggest bar/column, and using its millimeter value determine the value for all the other bars/columns
- Now you can recreate the data chart. Since your values are not 100% accurate, do not use data labels, but simply put a value axis on the side of the graph (like it was the case in the source image).
Extracting data from a poor graph
Sometimes the image quality of a graph is low, and/or the color scheme does not match yours, that you may want to recreate the data chart in PowerPoint. If there are proper labels, it is no problem. If not, here is a fix: