BPP for kodim19.png from the Kodak datasetįigure 3: SSIM vs. Images chosen from the 3 public data sets we have used.įigure 2: SSIM vs. Following figures show such SSIM vs bpp plots for the 3 Then for each quality value we plot the SSIM and bpp achievedįor JPEG and WebP. Source PNG image, compress it to JPEG and WebP using all possible (0-100) bits per pixel (bpp) plots for JPEG and WebP. We study the rate-distortion trade-off of JPEG and WebP. Table 3: Average file size for WebP and JPEG for same SSIM indexįrom the tables above, we can observe that WebP gives additional 25%-34%Ĭompression gains compared to JPEG at equal or slightly better SSIM index. Table 2: Average file size for WebP and JPEG for the same SSIM index Table 1: Average file size for WebP and JPEG for the same SSIM index Have also included JPEG quality parameter 75 since it is the generally Quality parameters 50 andĩ5 represent the image compression at low and high bit-rates respectively. Values (50, 75 and 95) of JPEG quality parameter Q. The following tables show the results of this experiment for three different The average file size and SSIM for JPEG and WebP images. We ran the above two steps on all the images in a dataset and then measured The steps of the experiment are asĬompress the source PNG image to JPEG with a fixed quality parameter QĪnd record the SSIM between the source PNG image and the compressed JPEGĬompress the same source image to WebP with a quality parameter thatĪchieves the above recorded SSIM as closely as possible. In this experiment we generate JPEG and WebP images at comparable SSIM valuesĪnd measure the ratio of file sizes. Similar in nature to the standard test suites, we ran a face detectionĪlgorithm over these PNG images and considered only those images (aroundġ1,000) for this experiment, that passed this detection test.Įxperiment 1: WebP vs. Photographs, rather than computer generated images. However most images in the standard test collections are like The crawled PNG images are icons, graphics, charts, scanned documents,Įtc. Sample of PNG images from Google Image Search web crawl database. Image_crawl: To test a large number of images, we collected a random We used the 100 original size RGB color images. Tecnick: 100 images from the collection available at The following are the list of data sets used in the We chose the data sets to evaluate standard test image collections as well as
#Jpg file comparison tool code
We used in the experiments from the code repository for reference. Publicly available implementation in C++. Generally accepted as a better quality metric than PSNR. The quality of an image was measured using SSIM. We set all other parameters to their default We used cjpeg and djpeg toĮncode and decode JPEG image. We used theĭefault encoding and decoding parameters of these tools.Ĭjpeg and djpeg are command-line tools that are part of the libjpeg We usedĬwebp and dwebp to encode and decode the WebP images. We used identify to extract the width and height information of anĪre command-line tools that are part of the libwebp library we We used convert to convert between PNG and PPM formats. Identify and convert are command-line tools that are part of The command line tools used for this experiment are: Only publicly availableĬommand line tools are used to keep the experiments reasonably reproductibleįor others. Large collection of PNG images that were crawled from the web.Įach experiment consists of running a set of commands. Obtained from publicly accessible standard test image suites as well as a The data sets for the experiments consist of PNG images. These plots show the rate-distortion trade off for WebP and JPEG. Second case, we analyze SSIM vs bits per pixel (bpp) plots for WebP and JPEG. JPEG images and then compare the file sizes of WebP and JPEG images. Particular, we generate WebP images of same quality (as per SSIM index) as the In the first case, we study theĪdditional compression achieved by WebP at the same quality level of JPEG. SSIM is considered to be a better visual quality We use in this study Structural Similarity orįor this study. Based on feedback from the community, we conduct theĮxperiments on PNG images including images available in a few standard test JPEG is a lossy compression format and introducesĬompression artifacts to the source. Our earlier comparative study of WebP focused onĮvaluating a large number of images and was conducted on JPEG sources that Image compression achieved by WebP and JPEG. The goal is to run a set ofĮasily repeatable experiments using publicly available tools and compare the The new encoder that we released in libwebp. We do a comparative evaluation of WebP and JPEG image compression based on
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