It is important to remember that images and graphics can help break up text. You can convey complex information visually – through charts and graphs. When using images from the internet, trying searching Creative Commons for royalty free images. And always give credit to where you found your pictures. Like using colour, don’t over do it.
Empty space is not negative space.
Aim for 40% graphic content; try to find ways in which to show your research visually.
Vector based mages (.ai, .eps, .svg, and some .pdf) are based on a mathematical equation. For example, if your image is a circle in vector format, that circle is simply a mathematical formula. If you resize that circle by 1000x, the mathematical formula would still calculate that circle in proportion. This means that no matter how you resize vector images they will scale properly and there will never be any pixelation.
Raster based graphics, (.bmp, .jpg, .png, .gif, .tif, etc.) are based on a grid of pixels or dots. The pixels represent certain colors that make up a bigger image and are resolution dependent. When you resized a raster graphic, they eventually start to pixelate due to the pixels being “stretched” beyond their original size.
Public Domain Images
Creative Commons Images