QUESTION
LaTeX documents print beautifully, but images often looks "ugly", "pixelated" or "low-res" compared to the text. By images I don't mean photos, which I rarely use, but rather diagrams, charts and drawings made in other programs such as Visio, Excel and Photoshop. I would love for these to look just as good as the rest of the report when printed.
ANSWER
Vector Imagery
If you can, save diagrams as a vector-based format such as PDF or EPS- these formats can be readily included in LaTeX documents and scale without appearing pixelized. Note that PDF should be used for input to pdflatex and EPS should be used with plain latex.
Inkscape is an excellent, free, cross-platform program for creating and editing vector graphics- similar to Adobe Illustrator. There is even a project that is producing a plug-in for Inkscape that allows Inkscape graphics to be exported to TikZ.
TikZ is a TeX-based language for creating vector graphics- it is incredibly expressive and lets you create graphics right inside your TeX document. However, using TikZ requires writing out the commands required to create an image- it is not a GUI-based drawing program.
If you are using latex instead of pdflatex, then the PSTricks package is also available- but your document must be rendered into PostScript somewhere along the for the images to appear. However, passing through PostScript has advantages- PostScript is a complete programming language for creating graphics which PSTricks is able to leverage in order to produce some effects that are difficult/impossible to replicate using TikZ.
Raster Imagery
If all you have is a raster image, PNG, JPEG, GIF, TIFF, ect, then you must pay close attention to the resolution that the image file has been saved at. The resolution will determine how much scaling can occur before the image starts to appear pixelated.
Many programs default to saving images at 72 dpi (dots per inch) as that is a lightweight resolution that is commonly used for images displayed on the web. However, for printed output you need a much higher resolution for the results to look good. A common rule of thumb is that the final scaled image should have a resolution of at least 300 dpi if it is to appear on a printed page without noticeable pixelation.
Tweet