Due to SmartPhone limitations, it is wise to be careful with graphics. There are a few simple rules to follow when creating graphics for mobile devices.
Your graphics should be no wider then 200 pixels.
Be careful when embedding text in graphics since the screen may be too small to be able to read the text e.g. see how hard it is to read the pie chart annotations.
If the graphic is too large, the learner might need to scroll horizontally and vertically to see it. This can become frustrating for your learner.