The online advertising market is showing signs that it's returned to a growth trajectory.

The Interactive Advertising Bureau tallied a 7.5 percent rise in first-quarter U.S. online ad spending compared to the same period a year ago. According to the IAB's audit, conducted by PricewaterhouseCoopers, first-quarter revenue totaled $5.9 billion.

Separately, comScore released data that shows the online industry served 1.1 trillion ads to U.S. consumers in the first quarter. The firm estimates U.S. online display ad spending in the quarter at $2.7 billion, with an average impression cost per thousand of $2.48.

ComScore viewed the figures as confirmation of a "strong resurgence in the online display ad market."

Similarly, PwC Assurance partner David Silverman said in a statement that the IAB figures show "continued signs of an improved economy and interactive advertising industry."

The IAB found a sequential decline of 6 percent in online ad spending from the Q4, traditionally the strongest quarter of the year.