The goal of image compression is to reduce the image size, which is beneficial for storing images and downloading images from the internet.
With JPEG images, there are many parameters for image compression, including Baseline JPEG (Standard JPEG) and Progressive JPEG encoding methods. Baseline JPEG and Progressive JPEG do not mention much about the size and quality of the image after compressing, but its goal is how the software will load and render it.
Choosing which encoding method depends on the intended use of the image, first need to understand the meaning of Baseline JPEG and Progressive JPEG, and then decide to use the appropriate encoding method.
What is Baseline JPEG?
Baseline JPEG is the standard encoding algorithm of JPEG (Standard JPEG). Most image viewer software supports this.
The way Baseline JPEG loads and displays is basically top-down and left-to-right processing. With large image, slow-loading images, the images are displayed line by line.
This effect is also noticeable in the case of web browsers displaying Baseline JPEG when images are loading slowly.
For images loaded locally from the hard drive, loading and rendering speed is often very fast, so it is difficult to realize this.
What is Progressive JPEG?
Progressive JPEG loads and displays the image "broadly". Image viewer softwares load a portion of an image quickly, then display a rather blurry image, and then continue loading the image until enough data and displays a full version of the image.
With this approach, loading and displaying, viewers will get some information of the image quickly, and then see a full version later.
Difference between Baseline JPEG and Progressive JPEG
The difference between Baseline JPEG and Progressive JPEG is not in the storage size or display quality, but in the way it is displayed.
Baseline JPEG does not provide enough information at the beginning, but it is not misleading that the data is fully loaded and this is the final result, but it feels like the data is loading too slowly.
Progressive JPEG is responsive to the user and provides some quick information, but it's easy to mislead as this is the end result. It is very difficult to distinguish whether this is a blurred image or an image that has not yet loaded the data.
With 2 different approaches, Baseline JPEG is suitable for storing and viewing images on a local machine. Progressive JPEG is suitable for use with websites.
How to save images as Baseline JPEG or Progressive JPEG?
Programs that view, process, and convert images will usually have the option to store Baseline JPEG or Progressive JPEG encoded images. If the software does not have this option, it usually uses encoding method of original image or default is Baseline JPEG.