PNG files are frequently used in websites because it’s the only widely supported format that can store partially transparent images. JPEG files have various uses in websites, from full-sized image background, galleries, thumbs for articles, news etc. The resulting file for both PNG and JPEG can be large and it’s charging the load time, so the users become frustrated.
Here are 2 online tools you can use to reduce the file size:
TinyPNG uses smart lossy compression techniques to reduce the file size of your PNG files. By selectively decreasing the number of colours in the image, fewer bytes are required to store the data. The effect is nearly invisible but it makes a very large difference in file size.
JPEGmini is a patent-pending photo recompression technology, which significantly reduces the size of photographs without affecting their perceptual quality. The technology works in the domain of baseline JPEG, resulting in files that are fully compatible with any browser, photo software or device that support the standard JPEG format.