If you do not have access to the source data of a graph you have two approaches to getting the data into your presentation:

1. Use a screen shot

How to get the best looking chart from a screen shot:

• Make the chart as big as possible on your screen. Sometimes you can click the graphic which opens in a new tab in your browser. In PDF, you can zoom in without losing quality. Take the screen shot of this big graph and paste it big in your slide.
• Crop out all items of the graph that you can easily recreate in PowerPoint or Keynote: axis labels, chart titles, even the values on the X and Y axes. Next, recreate these items by hand in PowerPoint
• Cover as many elements on the chart as possible with a white box. Legends for example hardly ever look good. Cover it and create your own.
• Select the chart and pick "format picture" to see whether it looks better in black and white. Alternatively, use the colour picker to get your legend use the exact colour used in the chart.

2. Measure and recreate

When you do not use data labels in a chart (bar, column, line) but rely on a value axis instead, you can get a way with a lower of level of accuracy. You can literally print a chart out (the larger the better), measure the position of the data points and recreate the chart from scratch in PowerPoint or Keynote.

Art: Interior of a tailor workshop, artist unknown, 1780.