The 26th May 2008 may well see one of the biggest battles ever seen between the giants of microstock image libraries.

Until now, iStockphoto and Shutterstock have coexisted relatively peacefully with only intermittent public slanging matches but it’s no secret that they are fierce competitors. Both specialise in selling stock images at low prices but with a difference. But all of that is about to change.

Until now, their business models have been different enough to appeal to slightly different markets. If a buyer needs just a few images on an intermittent basis then the choice is simple, go to iStockphoto and pay as little as 75 cents to a few dollars per image depending on the size needed.

If the buyers needs a large quantity of images then the obvious choice would be to go to Shutterstock and buy a monthly subscription for a few hundred dollars but be allowed to download as many as 750 images per month with an overall cost per image as little as 40 cents.

This difference in business approach means that each customer base is different enough to allow the giants to coexist relatively peacefully but that peace may about to be shattered with iStockphoto taking a step that threatens the very existence of the subscription only based model offered by Shutterstock.

iStockphoto are about to introduce a subscription based model of their own in addition their existing low cost single image sales that may give them a significant advantage over their nearest rival. And with subscription prices on iStockphoto starting as low as $96 compared to Shutterstock’s $299, it may even threaten the very existence of Shutterstock.

Of course there are numerous other microstock image libraries that have attempted to introduce subscription based models but none of these have been successful because they don’t have an existing significant share of the market, high enough profile or simply don’t offer the same value. However, iStockphoto has all of these and if they capture enough buyers on their subscription model then Shutterstock could suffer, particularly as iStockphoto have a significant number of exclusive images with their exclusivity program offering them a further advantage in the competition for buyers.

However, Shutterstock isn’t going to be pushed aside so easily, they have announced new pay increases for their photographers in May and have hinted at the possibility of new lower priced subscriptions over a shorter period for buyers. How this will work hasn’t been fully released yet but it may be weekly subscriptions priced at a level to compete with iStockphoto.

I’m sure the forums on both sites will make for interesting reading over the next couple of months but one thing is for sure. We are about to see one of the biggest showdowns ever between the microstock giants.