Today, some little-known techniques for optimizing PNG images are on the agenda. Most likely, you are already using some image optimization services or the optipng, pngcrush or pngout utilities. I’ll show you what you can do to make your images even smaller. The PNG format assumes no loss in quality when saving images. But in some cases, saving with distortions (Dithering or posterization) allows you to get images that are almost the same as the original, but much smaller. 1. Posterization, palette and grayscale png_2 Posterization (not to be confused with pasteurization ) allows you to reduce the number of colors in a PNG file due to some kind of adaptive algorithm (for example, mediancut or k-means).
Usually, reducing the number
of colors by 2-3 times is imperceptible to the eye, but leads to a decrease in image size by 20-50%. The most famous pasteurization tools Canada Phone Number List are Photoshop, pngquant , pngnq and TruePNG . . 2. Opacity mask png_3 A little-known technique, well described by Sergey Chikuyonok . Its essence lies in the removal of color information (zeroing) from completely transparent pixels. This reduces the actual number of bytes in the IDAT chunk and allows more optimal filters to be applied. Fortunately, some PNG optimization utilities, such as TruePNG, allow you to do this automatically.
Blur (dithering) png_4 A more interesting
Technique from Sergey , applicable not only to PNG images. The bottom line is to select areas of the image that can be blurred (apply dithering) while maintaining visual quality (or rather, highlight areas of the image for which blur cannot be applied). This optimization technique is not a lossy technique, but the final image will be different from the Australia WhatsApp Number List original, so it is important to choose parameters that minimize quality loss (visually). Dithering allows you to enhance the compressibility of the image filters (by discarding some color information). Fine tuning saves up to 20% of the image. In the automatic version, Dithering is not yet applicable, but your favorite graphics editor will allow you to do this using masks and selective filters for a PNG image.