From time to time we hear about other image optimization services claiming that they can compress images more than ShortPixel. As the leading WordPress image optimization service, we focus on always achieving the smallest image size while keeping the quality above a certain threshold. That does not mean your files will not be compressed; in fact, ShortPixel almost always gets the smallest file too!
Images can always be reduced in size by simply reducing the quality – you can do that with the simplest image editor – but we have designed and developed our algorithms (Lossless, Glossy, and Lossy) to produce the smallest possible image while keeping the quality at a certain level. In fact, our algorithms try to compress each image in different ways, choosing the one that gives the smallest size while maintaining a certain level of resemblance to the original.