Put simply, gif is generally a fraction of the size of png. Broadband internet access in the UK is 50-60%, that means that 50% of people are using a slow connection and will be waiting for your website to load. For images jpg are probably more suitable, for buttons and graphics use gif and png for specialist images. You should make several versions of your image and compare file size vs quality. If you want to exclude 50% of your clients... Your target audience may be corporate - 100% broadband. Take a view.
bcz GIF are smaller in size, using a large size image in themes and/or templates is just gonna make u loose bandwidth really fast...
Alright then, since you BOTH seem to know more about GIF and PNG than me and the internet @Campolar and @Tom the Corset Maker, I propose we find out for ourselves right here, right now. YOU supply me with an image - any image. Better yet, supply me with TWO, any size, different content. What I will do, is save the image as a GIF, and also as a PNG, and we can check the filesizes just to be sure! Does that sound okay to you two? I mean, it's one thing to make a suggestion, but to make an unsubstantiated claim that happens to be totally false, when the truth has been already previously stated takes either a lot of ignorance of the facts, or shows that you didn't really read the thread before you posted in it. So, I'll check back, I expect to see 1 or 2 images, which I will then save as GIF and PNG. I will say right now, the PNG will be smaller than the GIF, but you've both said otherwise so lets put your word against mine in a fair duel. I'll be waiting.... EDIT I'm impatient, and given the track record of those involved I seriously doubt they'll step up anyway. So instead I took a perfect example image: the DP logo! The first file is the DP logo as it appears on this site. Snazzy! The second file is my attempt at shrinking the size of it even further, but as it turns out whoever saved it the first time did a really good job! The third file is my PNG I made from the DP logo gif, it's 100% the quality of the GIF and uses the exact same settings. Now, the reason why it's smaller is because it uses a smarter lossless compression algorithm. Yes, PNG's *CAN* do full colour, in which case they're larger in size than a GIF, but when you instruct a PNG to use only 256 colours like a GIF, it saves smaller sizes. Point proven, and yes, my offer still stands, I'll compare filesizes for any images anybody throws my way here, I'm still open. What I would REALLY hope, more then do a little file-saving magic, is for CAMPOLAR and TOM THE CORSET MAKER to learn something here: 1) PNG's are in fact smaller than GIF's at the same size 2) DONT state unproven stuff in threads trying to help people, because if it's not true, you're misleading them which is worse than you just not saying anything at all 3) READ the entire thread before you post your reply. And I mean actually listen to what the people are saying, don't just recognize the words and then go ahead and post whatever you want. So, there it is, PNG's really ARE smaller and more efficient than GIF's if saved at the same quality as a GIF. PROVEN
@innovati: I was going to reply directly to this poster, but you literally took all the words out of my mouth. Good advice .
Huh? In my decade of graphics experience, this isn't true. I get much better compression with PNG graphics, especially by playing with reducing the color depth to the minimum amount of colors required to produce a nice result.
JPEGs should *ONLY* ever be used for photographs that contain no additional data (no images or text added on top of them) I mean, it's like a can-opener, it's INCREDIBLY useful for opening cans (as it was deisgned for) but not very good at anything else. Are can openers good? sure! but they're not good when you need a pair of scissors. The reason we have so many different image formats, is that we have so many different things we need images for. JPEG stands for Joint Photographic Experts Group, and it was designed to reduce photographic content without sacrificing quality over the entire picture. It tries to be content-aware to some extent so it doesn't compress the wrong things. Now, it wasn't designed for mechanical things, like text, or gradients - and it doesn't do a great job of those, but who can blame it, it was never supposed to anyway. PNG it lossless, it saves 100% quality. There's not degradation and you can keep opening and re-saving it as many times as you want and it will stay at 100%, this maks it great for text, gradients, buttons and all sorts of designed stuff. It's great for pictures too, perfect in fact! If you use PNG's all the time, and save them efficiently, you can't possibly go wrong. If you use JPEG for photographic pictures and you use light compression, you might not be able to see the difference, but the files will be a tiny bit smaller. BONUS! great, you've used JPEG correctly and squeezed a little more space out of the files. PNG ought to be your default, and use JPEG sparingly, and only where it applies. But knowing the difference and why they're good and when to use them is the hard part.
photos -> jpg web graphics with transparency -> png both of them when mixed gives a good reduced graphics size
web graphics without transparency -> png images of text -> png animations that can't be in flash -> gif