Image Optimization, Part 4: Serial JPEGs - To Be Or Not To Be?

Original author: Stoyan Stefanov
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Note: Below is a translation of the note “Image Optimization, Part 4: Progressive JPEG ... Hot or Not?” from the YUI blog . In it, Stoyan Stefanov, already known from past articles, examines the use of progressive JPEGs in terms of client optimization. My comments are further in italics.

In her previous article, “Image Optimization, Part 3: 4 Steps to Reduce File Size,” sequential JPEG files were casually mentioned as one of the options for optimizing JPEGs. This article addresses this issue more deeply, including the results of an experiment on 10,000 images.

Basic ( baseline ) and progressive JPEG



Basic JPEGs are “regular”: files of this type are supported by all image editing programs. Browsers download them sequentially, from top to bottom, as information comes from the network.

Загрузка базовых JPEG

Download a basic JPEG file in a browser. By clicking the full version will open.

Serial JPEGs are another variation of this format: they are loaded (as the name implies) sequentially. First you will see a low quality picture. Then, as graphic information arrives, the image quality will gradually improve.

Загрузка последовательных JPEG

Download consecutive JPEGs. By clicking the full version will open.

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