This is one of those things which isn’t so easy to find, so here’s my contribution.

The Problem

You’re using LaTeX, and have a small image which you want to display inline with the text (i.e. not a float). So, you use something like the following:

...indicate whether the phrase you've constructed is valid (\includegraphics{tick.png}) or not (\includegraphics{cross.png}}). To make things...

This works, but often the vertical alignment is not quite right, as shown in the images below:

Inline images, non-aligned

Zoomed (x600)

The Solution

After some searching and experimenting, I found the best solution to be using the \raisebox command with a negative value, like so:

...indicate whether the phrase you've constructed is valid (\raisebox{-1mm}{\includegraphics{tick.png}}) or not (\raisebox{-1mm}{\includegraphics{cross.png}}). To make things...

The additional code is minimal and it works perfectly (as far as I can tell). Results as below:

Inline images, properly aligned

Zoomed (x600)