Google compression algorithm

Google compression algorithm. We propose an efficient deep lossless compression algorithm, which uses arithmetic coding Oct 11, 2019 · Such research responds to the requirements of data transmission at high speed over networks. The camera rig features 46 synchronized 4K cameras Mar 16, 2017 · And while Guetzli produces smaller image file sizes without sacrificing quality, we additionally found that in experiments where compressed image file sizes are kept constant that human raters consistently preferred the images Guetzli produced over libjpeg images, even when the libjpeg files were the same size or even slightly larger. 2 days ago · Lossless WebP compression uses already seen image fragments in order to exactly reconstruct new pixels. On 10Web hosting, brotli is enabled by default. - google/zopfli Snappy (previously known as Zippy) is a fast data compression and decompression library written in C++ by Google based on ideas from LZ77 and open-sourced in 2011. When used at low bit rates, lossy compression algorithms produce compression artifacts. Here's a comparison among these algorithms: Approach:Greedy algorithm: Makes locally optimal choices at each step with the hope of finding a global optimum. 99 a month for 100GB of storage space across Google Photos, Google Drive and Gmail, and scales up based on how much storage you Feb 1, 2023 · WebP's lossy compression algorithm is based on a method that the VP8 video codec uses to compress keyframes in videos. Aug 23, 2021 · The fastest algorithm, Iz4 1. Snappier is a pure C# port of Google's Snappy compression algorithm. Search. Oct 4, 2021 · Typically, the training of such machine learning algorithms on time series requires to access the data in temporal order for several times. Numerous benchmarks are conducted on different sets of data corpus. Brotli is a lossless data compression algorithm developed by Google. Full implementation of the algorithm with an option to choose the compression level is used in the . TIFF also offers special-purpose lossless compression algorithms like CCITT Group IV, which can compress bilevel images (e. Gzip and Brotli are the two most common algorithms used for compressing HTTP data today. The smaller compressed size Oct 28, 2021 · Images are now employed as data in a variety of applications, including medical imaging, remote sensing, pattern recognition, and video processing. The main goal in its design was to compress data on the Internet, which meant optimizing the resources used at decoding time, while achieving maximal compression density. [9] Sep 22, 2015 · Officially unveiled and released to the world at large today, it's the successor to a different compression algorithm called Zopfli, which Google published in 2013. HTTP compression is a capability that can be built into web servers and web clients to improve transfer speed and bandwidth utilization. How Flate works. , faxes or black-and-white text) better than PNG's compression algorithm. May 10, 2010 · Deflate is the pure compression algorithm, while GZipStream includes a CRC checksum and could be extended by writing different compression algorithms (The current . [7] [8] This is typically true for web content that is served with Deflate-based HTTP compression or web content in a Deflate-based file format such as PNG or WOFF font files. It deals with the art and science of storing information in a compact form. Mar 21, 2017 · Google has released a new open source image compression algorithm called Guetzli. In this paper, we focus on deep analysis of the most common techniques in image compression. If you only have a few static points, you may also wish to use the interactive polyline encoding utility. Abstract— This paper compares six compression techniques, and based on the results proposes that brotli could be used as a replacement of the common deflate algorithm. It is publicly available on GitHub and its data format was submitted as RFC 7932 in July 2016. Both Brotli and ZStandard can further increase their effectiveness by using a compression dictionary, which is a collection of additional patterns that these algorithms can use during compression. Yesterday, the company followed it up that with a new open-source compression algorithm known as A compression algorithm is a technique used in computer science to reduce the size of a file without removing information. We added the sorting algorithms to the LLVM standard C++ library — replacing sub-routines that have been used for over a decade Sep 22, 2015 · and Bzip2 Compression Algorithms Jyrki Alakuijala, Evgenii Kliuchnikov, Zoltan Szabadka, and Lode Vandevenne Google, Inc. Divide and conquer algorithm: Breaks down a probl Jul 13, 2016 · This witty book helps you understand how data compression algorithms work—in theory and practice—so you can choose the best solution among all the available compression tools. It can also use a local palette if no interesting match is found. The evaluations consistently show that SnappyR provides a better compression ratio comparing to Snappy, as well as LZ4 Sep 11, 2023 · Greedy algorithm, divide and conquer algorithm, and dynamic programming algorithm are three common algorithmic paradigms used to solve problems. While numerous compression algorithms have shown remarkable In computer science and information theory, a Huffman code is a particular type of optimal prefix code that is commonly used for lossless data compression. These enhancements make the algorithm feasible for real-time video compression in applications such as video-on-demand, interactive multimedia, and videoconferencing. Compared to the good ol' gzip file compression and decompression algorithm, Brotli's open source algorithm shrinks data by an additional 20 to Snappy is widely used inside Google, in everything from BigTable and MapReduce to our internal RPC systems. The proposed algorithm consists of four parts TIFF also supports the compression algorithm PNG uses (i. Image compression plays a vital role where there is Jun 10, 2018 · Public domain — Inventor says Google is patenting work he put in the public domain Creator of a breakthrough compression algorithm fights to keep it patent-free. The reference library offers a very wide range of speed / compression trade-off, and is backed by an extremely fast decoder (see benchmarks below). Images look better, too. Brotli is a compression algorithm that boasts faster compression times and greater compression of webpages than its predecessor GZIP. It's backed by a very fast entropy stage, provided by Huff0 and FSE library. Lempel-Ziv 77 (LZ77) algorithm is the first Lempel-Ziv compression algorithm for sequential data compression. During dictionary coding, data size is reduced by searching for matches between the input data and a “dictionary” of known values, then Mar 1, 2021 · Subscription prices for Google One start at $1. It also offers a special mode for small data, called dictionary compression. Compression speed: How quickly we can make the data smaller, measured in MB/s of input data The tranformation does not itself compress the data, but reorders it to make it easy to compress with simple algorithms such as move-to-front coding. It uses linear algebra operations to transform an image into a sparse matrix and then uses the inverse… Dec 13, 2018 · In this paper we proposed an efficient lossless DNA compression algorithm based One-Bit Compression method (OBComp) that will compress both repeated and non-repeated sequences. This paper provides the analysis of related research directions and advanced image compression algorithms with its advantages and drawbacks. Dec 6, 2018 · Brotli is an open source general-purpose data compressor introduced by Google in late 2013 and now adopted in most known browsers and Web servers. Zopfli Compression Algorithm is a compression library programmed in C to perform very good, but slow, deflate or zlib compression. com Fast: Compression speeds at 250 MB/sec and beyond, with no assembler code. Mar 14, 2013 · Digital Image Compression: Algorithms and Standards introduces the reader to compression algorithms, including the CCITT facsimile standards T. We present a detailed analysis of run-length, entropy and dictionary based lossless image compression algorithms with a common numeric example for a clear Aug 14, 2018 · In general practice, you'll probably get around 30-40% compression using a compression format like ZIP on a file that's mostly text. Sebastian Anthony - Mar 17, 2017 12:42 pm UTC Nov 23, 2021 · Despite extensive progress on image generation, common deep generative model architectures are not easily applied to lossless compression. 99 / £1. Genetics compression algorithms are the latest generation of lossless algorithms that compress data (typically sequences of nucleotides) using both conventional compression algorithms and genetic algorithms adapted to the specific datatype. It was published by Welch in 1984 as an improved implementation of the LZ78 algorithm published by Lempel and Ziv in 1978. 2, results in lower compression ratios; the one with the highest compression ratio (other than ZSTD), zlib 1. PSNR has some downsides when used as a quality metric of images. google. Data compression has important application in the areas of file storage and distributed systems. Feb 16, 2022 · Importantly, still image and video compression algorithms often exploit the same methods, and developments in one field can benefit the other. Blocks of data that never repeat are copied straight to the output. Brotli is based on the Lempel-Ziv compression scheme and planned as a generic replacement of Gzip and ZLib. The Gzip compression format has been around for almost 30 years and is a lossless algorithm based on the Deflate algorithm. XCZ [34] file formats developed by the homebrew community for the Nintendo Switch hybrid game console. e. Nasir Ahmed Pioneered Digital . Section 3 covers the conventional-learning-based cooperation methods, including learningbased implementation on intra-prediction, inter-prediction, in-loop filtering, post-processing, and Jun 28, 2020 · Google’s new system encapsulates the entire video stack; capture, reconstruction compression, and rendering- delivering a milestone result. Aug 28, 2024 · Polyline encoding is a lossy compression algorithm that allows you to store a series of coordinates as a single string. – Aug 19, 2024 · Ahmed developed a compression algorithm called the discrete cosine transform that underpins almost all of the image and video compression standards used online today. Lossless compression is advised for archive purposes and is widely used for comics, technical drawings, medical imaging, and clip art. In practice, compression algorithms are far more sophisticated than the previous example illustrates, and on the web, compression algorithms can be used to significantly reduce download times for resources. Different algorithms provide different results. Jul 16, 2022 · Classical lossless compression algorithm highly relies on artificially designed encoding and quantification strategies for general purposes. Compression algorithms. Jul 1, 2021 · Without any tweaking, I get twice the performance with zstd compared to the standard command-line gzip (which may differ from what your web server uses) while also having better compression. Modern compression algorithms like zstd can be really fast. The algorithm patches the differences between psychovisual modeling of the JPEG format by employing a search 2. Algorithm Example Shortcomings Variations: The Concept. It was originally defined by Phil Katz for version 2 of his PKZIP archiving tool and was later specified in standard RFC 1951. Deflate is a smart algorithm that adapts the way it compresses data to the actual data themselves. We have resurrected the 3D-DCT-based video compression algorithm by developing several enhancements to the original algorithm. Benchmarks against a few other compression libraries (zlib, LZO, LZF, FastLZ, and QuickLZ) are Apr 20, 2023 · Google's search algorithm determines what most people -- and probably you -- see when browsing the web. For example, VAEs suffer from a compression cost overhead due to their latent variables. Dec 28, 2023 · 2 KMNN COMPRESSION ALGORITHM. NSZ/. However, ZSTD shows substantial improvements in both compression speed and decompression speed, while maintaining a high compression ratio. Jan 6, 2019 · The compression algorithm used in zlib is the deflate method. The dictionary is a portion of the previously encoded sequence. The purpose of this Special Issue “New and Specialized Methods of Image Compression” was to provide a forum for new developments in the image compression domain. This help content & information General Help Center experience. It features an extremely fast decoder, with speed in multiple GB/s per core, typically reaching RAM speed limits on multi-core systems. The "trick" that allows lossless compression algorithms, used on the type of data they were designed for, to consistently compress such files to a shorter form is that the files the algorithms are designed to act on all have some form of easily modeled redundancy that the algorithm is designed to remove, and thus belong to the subset of files Apr 15, 2024 · JPEG is a lossy compression format and introduces compression artifacts to the source. For photos, the result can be nearly indistinguishable so long as the original file is under 16 megapixels. In fact, Brotli's high efficiency is achieved to some degree Zstandard, or zstd as short version, is a fast lossless compression algorithm, targeting real-time compression scenarios at zlib-level and better compression ratios. RVZ Wii and GameCube disc image file format. 4 and T. 1 Compression algorithm fundamentals Compression algorithms generally contain two main components: a dictionary-coding stage and an entropy-coding stage. net framework just implements that one compression algorithm). Lossy data compression algorithms are formed by research on how people understand the data. to extract region of interest (ROI) of the image, regional segmentation algorithm was used to divide ROI and background region (BG), and multi-level tree set splitting algorithm (SPIHT) was used to encode compression with different compression rates. However, compression as it stands in the computer science aspect is still as interesting as it was in 1980s, possibly even more so today with an estimated 463 Exabytes of data to be Zstandard is a fast compression algorithm, providing high compression ratios. Sep 3, 2021 · Lossy Compression Algorithms# The lossy compression algorithms are a step ahead in order to reduce the storage size of files. student at MIT, and published in the 1952 paper "A Method for the Construction of Minimum-Redundancy Codes". It is open-source, free to use, and already supported by modern web servers and browsers. Aug 30, 2023 · Compression algorithms do just that: find the biggest possible repeating blocks of data and replace each consecutive occurrence with a reference to the first occurrence. Our algorithm achieves speed comparable to algorithms based on the techniques of Lempel and Ziv, but obtains compression close to the best statistical modelling techniques. This article reviewed six static algorithms for lossless compression, and four algorithms May 31, 2021 · I still came away mostly impressed by the quality maintained after Google’s compression. Sep 1, 2023 · Compared to general image compression algorithms [10], the image compression method used in remote sensing applications needs more compression ratio because the original resolution of the remote sensing images is too large. See full list on developers. With tables, diagrams, games, and as little math as possible, authors Colt McAnlis and Aleks Haecky neatly explain the fundamentals. The process of finding or using such a code is Huffman coding, an algorithm developed by David A. You have to understand how these two algorithms work in order to understand deflate compression. Stable: Over the last few years, Snappy has compressed and decompressed petabytes of data in Google's production environment. Concepts from information theory as they relate to the goals and evaluation of data compression methods are discussed briefly. Point coordinates are encoded using signed values. Brotli is a generic-purpose lossless compression algorithm that compresses data using a combination of a modern variant of the LZ77 algorithm, Huffman coding and 2nd order context modeling, with a compression ratio comparable to the best currently available general-purpose compression methods. Google is the most popular search engine with more than 80% of the market share, followed by Bing, Yahoo, Yandex, Baidu and DuckDuckGo, each with less than 10%. Apr 5, 2024 · Google promises a 35% compression ratio improvement with Jpegli encoding. It is typically used for one-time compression of static content. Most lossy compression algorithms are based on Aug 15, 2012 · The lossless deflate compression algorithm is based on two other compression algorithms: Huffman encoding and LZ77 compression. … the author has done a very good job in explaining all these complicated concepts, and presenting related algorithms and their analysis, with a minimal May 30, 2015 · Google’s algorithm performs a little bit better, and we see that the best overall compression is still when you perform a Google compression first, and then a JPEGmini compression on top of it. Therefore, a compression algorithm providing good compression ratios and fast decompression speed is desirable. At the heart of Jpegli, you'll find a retooled version of JPEG XL's adaptive quantization heuristics algorithm. In 2012, a team of scientists from Johns Hopkins University published a genetic compression algorithm Aug 31, 2016 · There are three standard metrics for comparing compression algorithms and implementations: Compression ratio: The original size (numerator) compared with the compressed size (denominator), measured in unitless data as a size ratio of 1. Sep 22, 2015 · This new format allows us to get 20–26% higher compression ratios over Zopfli. This LZ77 algorithm applies to all binary data, by the way, and not just text, though text generally is easier to compress due to how many repeated words most languages use. We want smaller updates because it narrows the window of vulnerability. A framework for evaluation and comparison of methods is constructed and applied to the algorithms presented. In our study ‘Comparison of Brotli, Deflate, Zopfli, LZMA, LZHAM and Bzip2 Compression Algorithms’ we show that Brotli is roughly as fast as zlib’s Deflate implementation. Compression Tag 0008 16 'Adobe-style') with medium usage and support by applications. This substitution reduces the number of features and therefore also reduces the resources needed to store, process, and train models on that data. 0 or greater. Lempel–Ziv–Welch (LZW) is a universal lossless data compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch. 2. Image compression can be lossless or lossy. If the update is a tenth of the size, we can push ten times as many per unit of bandwidth. Jan 12, 2021 · It should be drastically simpler and faster than anything that uses trees in any capacity, such as Huffman coding, LZW or practically every compression algorithm that remotely tries to achieve better compression. (Snappy has previously been referred to as “Zippy” in some presentations and the likes. 9. Zip supports both lossless and lossy compression algorithms, so my question is really about what compression algorithm Google Drive uses to zip files before download. Besides Google, other commercial vendors (such as Cloudflare and DreamHost) have begun to deploy support for Brotli as well. It achieves this by finding a formula that describes the data and produces compressed data that appears more random. Dubbed Zopfli, the open-source algorithm will accelerate data transfer speeds and reduce DEFLATE is a lossless data compression algorithm that uses a combination of the LZ77 algorithm and Huffman coding. The compensation performance of 2x2 compression case is close to the original 2x2 case, and performs better than 4x4 compensation case with the same file size as it. One would have noticed that many compression packages are used to compress files. Jan 13, 2023 · Google Drive automatically compresses large files or groups of files before downloading, using the Zip file format. R Lenhardt Jun 12, 2023 · When applied to the 9-16 bytes range of hashing functions in data centers, AlphaDev’s algorithm improved the efficiency by 30%. Feb 28, 2013 · Cross-posted with the Google Open Source Blog The Zopfli Compression Algorithm is a new open sourced general purpose data compression library that got its name from a Swiss bread recipe. Mar 31, 2002 · Compression and Coding Algorithms describes in detail the coding mechanisms that are available for use in data compression systems. The well known Huffman coding technique is one mechanism, but there have been many others developed over the past few decades, and this book describes, explains and assesses them. It is designed with speed as the primary goal, rather than compression ratio, and is ideal for compressing network traffic. This overhead can only be partially eliminated with elaborate schemes such as bits-back coding, often resulting in poor single-sample compression rates. At a high level, it's similar to JPEG encoding: WebP operates in terms of "blocks" rather than individual pixels, and has a similar division between luminance and chrominance. Mar 17, 2017 · Biz & IT — Google reduces JPEG file size by 35% New algorithm is based on human psychovisual system. Huffman while he was a Sc. See "Performance" below. [35] Similarly, it is also one of many supported compression algorithms in the . The overall KMNN image compression algorithm is shown in Figure 1. The algorithm, dubbed Guetzil (that's Swiss German for cookie), is Image compression using neural networks have reached or exceeded non-neural methods (such as JPEG, WebP, BPG). D. This algorithm, which gets its name from the German word “brot,” which means bread in Switzerland, is the lifesaver for users wanting to leverage quicker load speeds and less bandwidth Jan 1, 2021 · In Section 2, we briefly summarize the learning-based compression via the image compression scheme since it can be seen as the basement of video compression. Shannon–Fano coding based on variable lengthword, means that some of the symbols in the information which will be encoded is represented with a code word. Feb 28, 2013 · Google releases a better compression algorithm. The modern developer community has moved on from working on compression algorithms to bigger and better problems, such as creating the next major NodeJS framework. Let’s dig into some of the benefits of using brotli compression. Compression reduces the cost of storage, increases the speed of algorithms, and reduces the transmission cost. [3] [4] It does not aim for maximum compression, or compatibility with any other compression library; instead, it aims for very high speeds and reasonable compression. We propose a high-speed lossless data compression algorithm, named SnappyR. To overcome Let us look at compression algorithms to understand this better. It is an implementation of the Deflate compression algorithm that creates a smaller output size compared to previous techniques. Jan 18, 2024 · Google’s compression algorithm, known as Brotli, is a powerful player in the digital world that redefines the effectiveness of data compression on the web. Unlike direct coding technique where two bits are assigned to each nucleotide resulting compression ratio of 2 bits per byte (bpb), OBComp used just a single bit 0 or 1 Jul 27, 2021 · One important area of research is data compression. Mar 1, 2013 · Google has released a new data compression algorithm it hopes will make the Internet faster for everyone. Gzip. Brotli is a generic-purpose lossless compression algorithm that compresses data using a combination of a modern variant of the LZ77 algorithm, Huffman coding and 2 nd order context modeling, with a compression ratio comparable to the best currently available general-purpose compression methods. Guetzli creates smaller file sizes without impacting the quality. , 2015). Image compression is the process of minimizing the size of images by removing or grouping certain parts of an image file without affecting the quality, thereby saving storage space and bandwidth. g. Please see the Snappy README file for more details on Snappy. This is a substantial leap over encoders. Mar 17, 2017 · Google has developed a new open-source image compression algorithm that it says can reduce the size of JPEG images by 35 percent. The impact of these algorithms. 6, JBIG, CCITT H. Whereas, loss of some information is accepted as dropping non-essential detail. The decompression algorithm used in zlib is the inflate method, which is the decoding process that takes a deflate bit stream for decompression and correctly produces the original full-size data or file. It is win-win. Data compression is ubiquitous throughout science and engineering and essentially any data of non-trivial size is stored or communicated in compressed form on any modern computer system. Compression algorithms are in essence block move algorithms. In this paper, we present TSXor, a simple yet effective lossless compressor for time series. Here's a complete working implementation in C i adapted from ‪Software Engineer at Google‬ - ‪‪Cited by 2,079‬‬ - ‪Data compression‬ - ‪human vision‬ Gipfeli-high speed compression algorithm. While these networks are state of the art in rate-distortion performance, computational feasibility of these models remains a challenge. (Both named after Swiss bakery Dec 11, 2023 · This is a toy example of how compression algorithms can be effective at reducing the transfer size of text-based resources. May 28, 2020 · Compression algorithms can help you optimize file size. Based on feedback from the community, we conduct the experiments on PNG images including images Because of its significantly slower compression speed, Zopfli is not suited for on-the-fly compression. The popular MozJPEG encoder, for example, only provides a 20% improvement over the traditional JPEG compression ratio. "The current book is intended for people interested in a basic understanding of the increasingly important field of data compression … . Sep 19, 2023 · It has long been established that predictive models can be transformed into lossless compressors and vice versa. Jan 27, 2024 · How can we compress language models without sacrificing accuracy? The number of compression algorithms for language models is rapidly growing to benefit from remarkable advances of recent language models without side effects due to the gigantic size of language models, such as increased carbon emissions and expensive maintenance fees. Oct 9, 2021 · The compression ratios are in the range of 57–72% for the Shannon–Fano method, which is average by comparing all other algorithms. The deflate method encodes the input data into compressed data. The latest development is claimed to reduce the size of JPEG images by 35 per cent. 261 and MPEG standards. Apr 12, 2023 · When digital video was introduced in the 1970s, improving video compression became a major research focus, leading to the development of many compression algorithms called codecs, short for Sep 23, 2015 · Two years ago, Google released the Zopfli compression algorithm, which saw large-scale interest. Feb 2, 2023 · Preliminaries. Jul 22, 2024 · Data compression As discussed, the relevant cluster ID can replace other features for all examples in that cluster. WebP Compression Techniques in Detail; A WebP file consists of VP8 or VP8L image data, and a container based on RIFF. The encoder examines the input sequence through a sliding window as shown in Figure 9. ) For more information, please see the README. May 25, 2024 · The objective is to represent an image using the fewest number of bits possible. LZ4 is lossless compression algorithm, providing compression speed > 500 MB/s per core, scalable with multi-cores CPU. Our work provides three novel contributions. The proposed algorithm is inspired by the fact that clustering can reduce the number of colours, multi-layer neural network (NN) reduces the dimension of data in the process of extracting data features. 11-1, suffers from a slow compression speed. Compression ratios aren't great however, works better on longer strings. Nov 30, 2019 · Dear Colleagues, Data compression is classic research area in computer science focusing on the efficient storage and communication of data. In addition, we used initially the Peak Signal-to-Noise Ratio or PSNR as a quality metric. What Google has done is to create a slightly higher compression ratio version of deflate compression. Jan 24, 2017 · The HTTP servers Apache and nginx now offer Brotli compression as an option. 59 / AU$1. Posted Mar 1, 2013 1:49 UTC (Fri) by rgmoore ( supporter , #75) (6 responses) This seems like the core of the article. Mar 10, 2023 · The canny edge detection method was adopted by Wang Yuanyuan et al. Clear search Aug 30, 2023 · A novel compression algorithm was adopted to compress De-mura compensation data, and the compression process was described in detail. In this paper, we mainly use several typical mutual information metrics and image quality assessment metrics to evaluate the characteristics of the soft compression algorithm. With the rapid development of deep learning, data-driven methods based on the neural network can learn features and show better performance on specific data domains. Mar 6, 2024 · Compression works well on the web because it substantially reduces resource load times. Incidentally, in recent years, the machine learning community has focused on training increasingly large and powerful self-supervised (language) models. Traditional methods like JPEG-2000 under an 8:1 compression ratio cannot perfectly meet the limited transmission bandwidth Aug 23, 2022 · In this article I walk through an image compression and decompression pipeline in Python. Since these large language models exhibit impressive predictive capabilities, they are well-positioned to be strong compressors As I described in Smaller is faster (and safer too), we wrote a new differential compression algorithm for making Google Chrome updates significantly smaller. [1]HTTP data is compressed before it is sent from the server: compliant browsers will announce what methods are supported to the server before downloading the correct format; browsers that do not support compliant compression method will download uncompressed Feb 1, 2021 · A survey of image compression algorithms involved in wireless multimedia sensor networks (WMSN) is given in (ZainEldin et al. It uses a combination of the general-purpose LZ77 lossless compression algorithm, Huffman coding and 2nd-order context modelling . Improved upon Snappy, we design new structures of the literal and the match tokens to achieve better compression ratio than Snappy. this book is nicely written and well organized. taq hzrbqag wvbhg tbnppku gsxyvewb dufi tnkdx hrttqn cghddq pzl