If you need to add text, arrows, or other annotations to an image, it's preferable to do so within LaTeX. Compared to using external graphics software, there are a few advantages:
You can use the same fonts as in the LaTeX document
Your annotations would be scalable in perfect quality, even if you would draw over a bitmap image
You can use macros from your preamble or packages
The style would be consistent with your other drawings and diagrams
You can change it at any time, and document-wide adjustments also have their desired effects on this annotated image
We will draw with TikZ. The key is using the onimage
package. If this is not available in your TeX distribution or on CTAN, you can download it from Launchpad at http://bazaar.launchpad.net/~tex-sx/tex-sx/development/view/head:/onimage.dtx.
Follow these steps:
Within the LaTeX document preamble, load the
onimage
package:\usepackage{onimage}
Define TikZ styles for your annotations:
\tikzset{annotations/.style...