Compression without artefacts with JPEGmini Pro

Minifying images for a website or compressing them for an email is a daily returning routine for most people who deal with illustrating any sort of textual content. You can always minify PNGs and JPEGs on the server. This works very well and if you’re managing a WordPress installation, there are a number of fine plug-ins that take the pain out of compressing images to their smallest possible size. But often compressing an image — and especially a JPEG — to its smallest possible size, introduces ugly artefacts. JPEGmini Pro seeks to avoid that.

JPEGmini reduces the file size of JPEG photos by up to 5X, while preserving the resolution and quality of the original photos. JPEGmini Pro is the top-end product of a range of JPEGmini apps that do just that: minifying JPEGs. JPEGmini Lite is a limited version for people who don’t need to make a lot of JPEGs smaller on a daily basis. JPEGmini lifts the limitation of the allowed number of minifications, but doesn’t use all your machine’s processor cores and has an image size limitation of 28MP. The Pro version does use all your cores and can process images of up to 50MP.

JPEGmini Pro interface

JPEGmini works its magic by implementing parameters that have been tuned to significantly reduce the file size without affecting perceptual quality. It uses a proprietary compressing or minifying algorithm that doesn’t introduce quality loss. It’s a bit like JPEG2000 or WebP in that respect — although Beamr, the developers of JPEGmini claim their JPEGmini algorithm often results in smaller files. One of the major benefits of JPEGmini’s algorithm is that it doesn’t require a whole new format such as WebP or JPEG2000. The results of a JPEGmini compression is still a JPEG file. The ‘new’ formats are supported by few — if any — web browsers.

JPEGmini works by analysing the input image using a quality detector that imitates the human visual system. Based on this analysis the app applies the maximum amount of compression that will not cause visible artifacts at 100% magnification. Size reductions of 70% to 80% should be the rule with JPEGs of over 8MP.

JPEGmini preferences

I tested JPEGmini Pro with three Hasselblad files of 40MP and a dozen 12MP files from my old trusted Sony Alpha. The app is fast. JPEGmini Pro actually took a lot less time than the WordPress EWWW Image Optimizer plug-in I’m using. I can run JPEGmini optionally within the EWWW Image Optimizer as well, but only as a cloud solution, which I dislike and therefore don’t use. The Independent JPEG Group’s JPEGTRAN command line script that I use takes a lot longer than JPEGmini Pro. For users who want to run JPEGmini as a server, they can. The Linux-based server edition costs $199.00 USD per month.

The minification/compression JPEGmini achieved was impressive and even a bit more than claimed with one of my photos. The quality of the JPEGmini result was identical to the original when viewed at 100%. That’s what the marketing on the JPEGmini site promises. When magnified at 200%, I could see tiny differences in small details, but as you can see in the images below, you need to really look.

Comparing JPEG with JPEGmini

An added benefit of the desktop edition is the nice interface, which has a gauge showing you the reduction rate or how much disk space you’ve saved by using JPEGmini. In addition, in the Preferences you can also set an image size reduction to one of three presets or a customisable maximum width or height. Finally, you can choose to have the originals minified or leave these alone.

JPEGmini comes with only one disadvantage: it only works with JPEGs. It would be even more awesome if it would work with PNGs as well. JPEGmini Pro costs approx. €115.00 EUR.

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