Transparent PNG images essential to web design. With the proliferation of mobile devices transparent PNG compression is a must. Adobe Photoshop CS5 and below bring nothing to the PNG compression table.
That’s where tinypng.org comes in. TinyPNG uses smart lossy compression techniques to reduce the file sizeof your PNG files. By selectively decreasing the number of colors 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! In a nutshell it takes your 24-bit PNG files and converts them to a much smaller 8-bit PNG files with 100% support for transparency. Have a look: