When saving a file as JPEG in Adobe Photoshop, you have the option to choose from three different JPEG formats: Baseline Standard, Baseline Optimized, and Progressive.
Baseline Standard is the most basic and widely compatible format. It is the default format and is supported by most web browsers and image viewers. It creates a standard JPEG file with a small file size, but it does not support interlacing.
Baseline Optimized is a higher quality format that is also widely compatible with web browsers and image viewers. It optimizes the encoding process to produce a smaller file size than Baseline Standard, while still maintaining a high image quality. It supports interlacing, which means that the image will gradually load in a series of scans, rather than waiting for the entire image to load before displaying.
Progressive is a format that also supports interlacing. However, unlike Baseline Optimized, it loads the image in multiple passes, with each pass increasing the image quality. This means that a low-quality preview of the image is displayed first, followed by a series of increasingly higher-quality versions of the image. Progressive JPEGs are generally larger in file size than Baseline Standard or Baseline Optimized JPEGs, but they can provide a smoother and faster user experience when loading large images.
In summary, Baseline Standard is the most basic format, Baseline Optimized is a higher quality format that supports interlacing, and Progressive is a format that loads the image in multiple passes, with each pass increasing the image quality.
Is this used for Web and viewing on screens only, or does it affect printing?
The different JPEG formats in Adobe Photoshop (Baseline Standard, Baseline Optimized, and Progressive) primarily affect how the file is displayed on screen and transmitted over the internet. They do not have a significant impact on printing, as most printers will convert the JPEG to their own format before printing.
That being said, using the Baseline Optimized or Progressive formats may result in slightly better image quality when printing due to the fact that they preserve more of the original image data during compression. However, this improvement is generally small and may not be noticeable in most cases. Ultimately, the choice of JPEG format should be based on the intended use of the file and the desired balance between image quality and file size.