This tool allows you to check if your image is encoded as a progressive JPEG.
Progressive JPEG Tester
Choose the image file you wish to test below:
What is a Progressive JPEG?
A progressive JPEG is an image created using compression algorithms that load the image in successive waves until the entire image is downloaded. This makes the image appear to load faster, as it loads the whole image in progressive waves. A standard JPEG loads the image from the top to bottom line by line.
You can read more about Progressive JPEGs here.
What is a Baseline JPEG?
A Baseline JPEG is stored as a top to bottom image that is loaded in one wave.
How does this Progressive Testing Tool work?
This wikipedia article lists some common markers of a JPEG image. Bytes “0xFF, 0xC2” represent the start of frame for a progressive image.
If the marker is present, then it is a progressive JPEG.