![]() Is chosen in those cases where it produces a smaller WebP image. For the lossy compression curve, the lossless compression Ratios are sorted, and shown for both lossless and lossyĬompression. ForĮach image, the size ratio to compressed PNG is computed, and the size Same images are compressed using both lossless and lossy methods. PNG compression density is used as a reference, at 1.0. We sorted these compression factors, and plotted them in Figure 3.įigure 3. WebP lossless with the smallest size (-m 6 -q 100)īest of WebP lossless and WebP lossy with alpha (default settings). We computed compression density for each of the images in the webĬorpus, relative to optimized PNG image sizes for three methods: lossy_8bit -lossy_transparent input.png output-candidate.png ZopfliPNG with all filters: zopflipng -iterations=500 -filters=01234mepb ZopfliPNG(3): zopflipng -lossy_transparent input.png output-candidate.png rem gAMA -rem cHRM -rem iCCP -rem sRGB -rem alla -rem text Pngcrush(2): pngcrush -brute -rem tEXt -rem tIME -rem iTXt -rem zTXt ImageMagick with adaptive predictors: convert input.png -quality 95 ImageMagick(1) with no predictors: convert input.png -quality 90 Recompressed all these original PNG images using several methods:Ĭlamp to 8 bits per component: convert input.png -depth 8 output.png To measure the full capability of the existing format, PNG, we have Viatour, Photo licensed under the Creative CommonsĪttribution-Share Alike 3.0 Unported license. "Jaipur Maharaja Brass Band" Chassepierre Belgium, Author: Luc ![]() Pngcrush, ZopfliPNG and the smallest version of each image is consideredįigure 1. These PNG images are optimized via convert, Image CorporaĪ single graphical image with translucency (Figure 2), andĪ web corpus: 12000 randomly chosen PNG images with translucency or not,Ĭrawled from the Internet. Has been evoked with -q 1 and -m 0 flags. ForĮxample, if we refer to cwebp -q 1 -m 0, it means that the cwebp tool We use the command line tools with their respective control flags. This is a command-line tool part of ImageMagick software These tools that are part of the libwebp libraryĬonvert. We use the following command-line tools to measure performance:Ĭwebp and dwebp. Image compression with lossless alpha support gives further possibilities in WeĮfficient replacement for today's PNG image format. To the reference corpus, we chose two larger images, one photographicĪnd the other graphical, for speed and memory use benchmarking.ĭecoding speeds faster than PNG have been demonstrated, as well as 23%ĭenser compression than what can be achieved using today's PNG format. Lossless and lossy WebP compression against this corpus. ![]() Reference corpus of web images using best practices, and compared both Highly compressed using pngcrush and ZopfliPNG. In this work, we compare the performance of WebP to PNGs that are At the same time, a number of new features - suchĪs separate entropy codes for different color channels, 2D locality ofīackward reference distances, and a color cache of recently usedĬolors - allow for improved compression density with most images. WebP as well, which results in similar speed and compression density The fundamental techniques used in PNG compression, such as dictionaryĬoding, Huffman coding and color indexing transform are supported in WebP supports lossless and translucent images, making it an alternative Replacement for PNG for use on the web regarding both size and processing In our results we show that WebP is a good Recompressed the PNGs in our corpus to compare WebP images to We useĪ corpus of 12000 randomly chosen translucent PNG images from the web,Īnd simpler measurements to show variation in performance. Abstract - We compare the resource usage of WebPĮncoder/decoder to that of PNG in both lossless and lossy modes.
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