![]() The Jpeg compression method is designed to compress JPEG images. XZ is an open-source data compression method that makes use of the LZMA2 algorithm to produce a higher compression ratio. ![]() PPMd is an open-source data compression algorithm that can compress most text-based data more effectively than either the traditional deflate or bzip2 methods, but which is quite often slower than either.Įarlier versions of WinZip referred to this compression method as Maximum (PPMd). It can produce a higher compression ratio than older methods. LZMA is an open-source data compression method that uses a dictionary compression scheme that uses a larger dictionary size than the deflate method. It can be particularly useful for compressing large files containing large amounts of highly compressible data such as large text files and text-based database files.Įarlier versions of WinZip referred to this compression method as Maximum (enhanced deflate).īzip2 is an open-source data compression algorithm that compresses most files more effectively than the traditional deflate methods, but it can be somewhat slower.Įarlier versions of WinZip referred to this compression method as Maximum (bzip2). The "enhanced deflate" method is similar to the original deflate but operates on larger chunks of data at a time, often resulting in improved compression. WinZip 12 and later no longer uses Fast and Normal when compressing files, but it can still extract files compressed with any of these methods. These all used the same basic technology but were optimized in different ways for speed vs. ![]() Therefore it will generally compress your files somewhat faster than Legacy, but the compressed files will be somewhat larger.Įarlier versions of WinZip supported four variants of the deflate algorithm, referred to as Maximum (portable), Fast, SuperFast, and Normal. It is the same basic algorithm as is used for Legacy compression (see above), but is optimized for speed rather than compressed size. This is a good, general-purpose compression algorithm known as "deflate". Therefore, to save time, it may be best to select None or No compression when you are adding a group of files that are already compressed. In most cases, these types of files cannot be further compressed to any significant degree by the available methods. For example, many multimedia and sound files, such as avi and MP3 files, are precompressed versions of images and sound. Some files that you may want to add to a Zip file are already compressed. Here is additional information for all of the compression methods supported by the current version of WinZip: Additional information on specific compression methods zipx files, respectively.įor more detailed information on each of the compression methods, see the Additional information on specific compression methods section below. Set the appropriate compression method in the. Setting the compression method is accomplished on the Zip tab of the WinZip ribbon. In the WinZip Ribbon Interface, you will need to select the appropriate compression method to use prior to beginning the zipping process. In making a choice of compression methods, there are several things to consider, including the type of data you are compressing, your plans for later unzipping the data, and the amount of time you are willing to wait while your data is being compressed. I wrote a blog post which explains how I received these numbers.WinZip ® provides several methods for compressing the files that you add to a Zip file. But I think these values are good as a rough estimate. So it is not so easy to understand what value should be taken as typical for a specific JPEG quality. for Q=55 min compression ratio is 22.91 while max value is 116.55) and the distribution is not normal. To tell the truth, the dispersion of the values is significant (e.g. After some Excel magic, I came to the following values (note, I did not calculated anything for JPEG quality lower than 55 as they seem to be useless to me): Q=55 43.27 I created a script which compress them with different JPEG quality values (it uses our company imaging library, but it is based on libjpeg, so it should be fine for other software as well) and saved results to CSV file. I took 60 real life photos from different devices with different dimensions. I cannot say that it is perfect, but it is definitely better than others. I had exactly the same question and I was disappointed that no one created such table (studies based on a single classic Lena image or JPEG tombstone are looking ridiculous).
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