MozJPEG's API is built around the concept of destination and source managers. As their respective name implies, destination and source managers tell MozJPEG where to read/write data before/after compression. The default ones are jpeg_stdio_src/jpeg_stdio_dest which read/write data from a file stream, but there is also the jpeg_mem_src/jpeg_mem_dest.
We are thrilled to let you know that the png compression is now done using the famous OptiPNG library. OptiPNG is one of the best optimizers for the PNG format.
We are happy to let you know that the /compress endpoint uses now MozJPEG behind the curtains. MozJPEG (or Mozilla JPEG) is fork of libjpeg-turbo introduced by Mozilla to improve even further the compression.
Although JPEG is an image format that has almost 30 years now, it is still shining. One interesting feature or innovation about the format, which not known to many, is the possiblity to make the loading of the image progressive. This means that the rendering of the image is done gradually by going through scans where each scan contains a certain amount of image data.
