We explored some options to optimize images like Trimage or Kraken earlier. TinyJPG is a new online service to squeeze images with a difference. It strikes a balance between quality and image size so that the difference between the optimized and original images is not visually detectable.
They explain how they d it on their website: the uploaded JPEG image is analyzed. Textures, patterns and colours are automatically identified. The encoder creates an optimally compressed JPEG file based on that information. The final result is compared with the orginal and fine-tuned. Distracting JPEG artifacts are minimized without big sacrifices in file size. Unnecessary metadata is stripped as well. This results in an optimal image size almost retaining the visual quality.
As it is a web service, there is nothing to download. I am quite interested to check how it fares against Kraken.