Twitter is changing the way it processes uploaded images, and the new way of doing things will be much-appreciated by any photographers sharing their work on the platform. Twitter engineer Nolan O'Brien shared that the platform will now preserve JPEG encoding when they're uploaded via Twitter on the web, instead of transcoding them, which results in a degradation in quality that can be frustrating for photo pros and enthusiasts.
There are some limitations to keep in mind -- Twitter will still be transcoding and compressing the thumbnails for the images, which is what you see in your Twitter feed. But once users click through, they will get the full, uncompressed (at least, not additionally compressed) image you originally uploaded, provided it's a JPEG.
Starting today, Twitter will preserve JPEGs as they are encoded for upload on Twitter for Web. (Caveat, cannot have EXIF orientation)
— Nolan O'Brien (@NolanOBrien) December 11, 2019
Twitter will also still be stripping EXIF data (data that provides more information about the picture, including when, how and, potentially, where it was taken or edited), which is readable by some applications. The platform has previously done this, and it's good that it does, because while sometimes photographers like to peek at this info to check things like aperture or ISO setting on a photo they admire, or to transmit copyright info, it also can potentially be used by people with bad intentions to spy on things like location.
The example above posted by O'Brien is actually a really illustrative one when it comes to showing what kind of detail and quality can be preserved when Twitter doesn't further compress or transcode your JPEG photos. This is a small, but great feature tweak for the platform, and hopefully it continues to make Twitter more photo-friendly in the future.