Convert WEBPs to JXLs

The JPEG XL (JXL) image format is a next-generation image coding standard that aims to surpass the capabilities of existing formats like JPEG, PNG, and GIF by providing superior compression efficiency, quality, and features. It is the result of a collaborative effort by the Joint Photographic Experts Group (JPEG) committee, which has been instrumental in the development of image compression standards. JPEG XL is designed to be a universal image format that can handle a wide range of use cases, from professional photography to web graphics.

One of the primary goals of JPEG XL is to provide high-quality image compression that can significantly reduce file sizes without compromising visual quality. This is achieved through a combination of advanced compression techniques and a modern coding framework. The format uses a modular approach, allowing it to incorporate various image processing operations such as color space conversions, tone mapping, and responsive resizing directly into the compression pipeline.

JPEG XL is built on the foundation of two previous image codecs: Google's PIK and Cloudinary's FUIF (Free Universal Image Format). These codecs introduced several innovations in image compression, which have been further refined and integrated into JPEG XL. The format is designed to be royalty-free, making it an attractive option for both software developers and content creators who require a cost-effective solution for image storage and distribution.

At the heart of JPEG XL's compression efficiency is its use of a modern entropy coding technique called asymmetric numeral systems (ANS). ANS is a form of arithmetic coding that provides near-optimal compression ratios by efficiently encoding the statistical distribution of image data. This allows JPEG XL to achieve better compression than traditional methods like Huffman coding, which is used in the original JPEG format.

JPEG XL also introduces a new color space called XYB (eXtra Y, Blue-yellow), which is designed to better align with human visual perception. The XYB color space allows for more efficient compression by prioritizing the components of an image that are more important to the human eye. This results in images that not only have smaller file sizes but also exhibit fewer compression artifacts, particularly in areas with subtle color variations.

Another key feature of JPEG XL is its support for high dynamic range (HDR) and wide color gamut (WCG) images. As display technologies evolve, there is an increasing demand for image formats that can handle the extended range of brightness and color that these new displays can produce. JPEG XL's native support for HDR and WCG ensures that images look vibrant and true-to-life on the latest screens, without the need for additional metadata or sidecar files.

JPEG XL is also designed with progressive decoding in mind. This means that an image can be displayed at a lower quality while it is still being downloaded, and the quality can improve progressively as more data becomes available. This feature is particularly useful for web browsing, where users may have varying internet speeds. It allows for a better user experience by providing a preview of the image without having to wait for the entire file to download.

In terms of backward compatibility, JPEG XL offers a unique feature called 'JPEG recompression'. This allows existing JPEG images to be recompressed into JPEG XL format without any additional loss of quality. The recompressed images are not only smaller in size but also retain all the original JPEG data, which means they can be converted back to the original JPEG format if needed. This makes JPEG XL an attractive option for archiving large collections of JPEG images, as it can significantly reduce storage requirements while preserving the ability to revert to the original files.

JPEG XL also addresses the need for responsive images on the web. With its ability to store multiple resolutions of an image within a single file, web developers can serve the most appropriate image size based on the user's device and screen resolution. This eliminates the need for separate image files for different resolutions and simplifies the process of creating responsive web designs.

For professional photographers and graphic designers, JPEG XL supports lossless compression, which ensures that every single bit of the original image data is preserved. This is crucial for applications where image integrity is paramount, such as in medical imaging, digital archives, and professional photo editing. The lossless mode of JPEG XL is also highly efficient, often resulting in smaller file sizes compared to other lossless formats like PNG or TIFF.

JPEG XL's feature set extends to include support for animation, similar to the GIF and WebP formats, but with much better compression and quality. This makes it a suitable replacement for GIFs on the web, providing smoother animations with a wider color palette and without the limitations of GIF's 256-color restriction.

The format also includes robust support for metadata, including EXIF, XMP, and ICC profiles, ensuring that important information about the image is preserved during compression. This metadata can include details such as camera settings, copyright information, and color management data, which are essential for both professional use and the preservation of digital heritage.

Security and privacy are also considered in the design of JPEG XL. The format does not allow for the inclusion of executable code, which reduces the risk of security vulnerabilities that can be exploited through images. Additionally, JPEG XL supports the stripping of sensitive metadata, which can help protect user privacy when sharing images online.

JPEG XL is designed to be future-proof, with a flexible container format that can be extended to support new features and technologies as they emerge. This ensures that the format can adapt to changing requirements and continue to serve as a universal image format for years to come.

In terms of adoption, JPEG XL is still in the early stages, with ongoing efforts to integrate support into web browsers, operating systems, and image editing software. As more platforms adopt the format, it is expected to gain traction as a replacement for older image formats, offering a combination of improved efficiency, quality, and features.

In conclusion, JPEG XL represents a significant advancement in image compression technology. Its combination of high compression efficiency, support for modern imaging features, and backward compatibility positions it as a strong candidate to become the new standard for image storage and transmission. As the format gains wider adoption, it has the potential to transform the way we create, share, and consume digital images, making them more accessible and enjoyable for everyone.