Images which contain math equations should be accompanied or link to a document with the equivalent equation marked up with MathML.

Example

Wrong

<img src="equation.png" alt="An equation which describes the average wind velocity of an unlaiden swallow. ">

Right

<img src="equation.png" alt="An equation which describes the average wind velocity of an unlaiden swallow. The equation is available after this image."><mrow><apply> <eq/> <apply> <plus/> <apply> <power/> <ci>x</ci> <cn>2</cn> </apply> <apply> <times/> <cn>4</cn> <ci>x</ci> </apply> <cn>4</cn> </apply> <cn>0</cn></apply></mrow>