Demonstration of Modified WebP

Gurulogic experimentally added couple of different technologies to WebP solution for improving compression performance by reducing encoded file sizes without deteriorating encoding and decoding times.

Next demonstration shows results of 22786 (all non HDR) Android repository images that are encoded and decoded with WebP that uses “near lossless” option vs. WebP that is modified by Gurulogic.

File size reduction is about 30 % with similar image quality that is measured by using Mean Square Error (MSE) criteria. The average quality in the demo corresponds to 47 dB PSNR (= very high quality)

Note! We recommend to switch the video to fullscreen mode after clicking play.

Lossless image compression performance

To test lossless image compression performance, we have encoded an image set called "android_master_5000" with various image codecs. The image set was selected by taking the first 5000 PNG images from the Android source repository, in alphabetical order, and excluding 10 images that have 16 bit color component depth, which WebP does not support losslessly. So the test set consists of 4990 PNG images we call "PNG_orig".

The graph below represents the distribution of image file size ratios of three codecs compared to the original PNG files. The ratio B/A means, how large the original PNG file is relative to the re-encoded file. The larger the B/A ratio, the smaller codec A's encoded file is compared to the original. For example, ratio 1.5 means that the original image file is 50 % larger than the re-encoded image file. Ratios below 1.0 mean that the re-encoded file is larger than the original source file.

Date of results: 2018-08-24

The table below shows more detailed numerical data from the distribution graph. "Better count" means the number of images for which codec A performed better than codec B (PNG_orig). "Worse count" means the number of images for which codec A performed worse than codec B (PNG_orig). Decoding time tests were performed on a Samsung Galaxy S6 phone.