Hi there, I was wondering if anyone know how to optimizing Images for website ? especially the .PNG file. I guess what I mean in optimizing is have great quality of pic(pixel) with small amount of size(kb). So it could save a lot of loading time. I've try some pic optimizer service/software/trick(like posterize on PSD) but I think they don't give 'good' shrink size(kb). sometime it's only shrink 4% of the original size(kb).
The thing about .png files is that they hold information for every pixel in rgba (red,green,blue,alpha [transparency]), so you really can't compress them. They're fantastic for icon type images so you can use some anti-aliasing for smooth edges regardless of background, but they're terribly inefficient for larger images, whereas .jpg would be the far better option. Personally I wouldn't suggest using .png for images larger than 256x256. On the other hand, they do support palettes for colors, which can help with file size, but again, only really useful for small images, especially since you'll need to use a separate palette entry for each level of transparency.