JPEG deblocking is a feature that has been available since the release of Flash CS4. It is an option in the publish settings that reduces the appearance of the common artefacts found in highly compressed JPEG files.

This option reduces typical artefacts resulting from JPEG compression, such as the common appearance of 8 × 8-pixel blocking of the image. Some JPEG images may lose a small amount of detail when this option is selected in the Publish Settings dialogue box.

To make highly compressed JPEG images look smoother when they are exported from Flash, select the Enable JPEG deblocking option in the Publish Settings dialogue box.