JPEG OR PNG? Which is better resolution?

[Get A Trip]

I am still not getting clear images after I bought all these expensive high resolution photos from Shutterstock. I purposefully chose the largest sizes thinking there would be less resolution degradation once I down-sized them.

Then tonight just on a whim I tried dowmloading a 72dpi instead of the normal 300 dpi and once I re-sized them to about 20% the original size, than the 72 dpi had the clearer image. How can this be possible? Granted the 72 dpi image started off much smaller, so had less way to shrink, as opposed to the 300dpi. Does this matter?

Second question: Should I be first saving Jpegs into a different format like png.'s first beofre resizing smaller for maximum resolution? I heard they had better resolution, is this true or rumour?

These photos are for a website where clarity comes first though load speed is all a consideration, though resolution clarity is first priority. Can I have the best of both worlds? Sorry, that's a 3rd question!

I really want to get this resolution thing down, especially considering the costs involved. Thanks for the consideration.

Regards, Terry

Edited June 18, 2011 by Get A Trip

[mountnman]

.jpeg vs. .png

jpeg images are lossy-- this means they "lose" details. the jpeg format was designed to lose any details that the designers decided the human eye couldnt detect(if i understand things right)

png images are lossless-- the "lose" nothing. every single pixel is saved at the colour it orriginally was

think of it like this- jpeg is the old standard tv, and png is a nice new hi-def tv

now on a side note- if you download a jpeg file and save it as png, it will still have the jpeg's detail lvl. most people relize this without being told, but... anyway you should still save more details that way when resized

i would use the png for anything that wasnt file size restrictive

one thing i have to ask.. you DO have a HD monitor, right? lcd? not sure how much of a png's detail would come across one that wasnt

as for why the 72 dpi being clearer.. i have no idea. one of the more tech savy people here will have to adress that

Edited June 18, 2011 by mountnman

[Simon Brown]

I recommend reading this tutorial. As for PNG vs JPEG, JPEG is lossy, which means quality is sacrificed to reduce file size. This happens every time a JPEG image is saved, so I suggest creating a PDN copy for editing (which is basically PNG with layers). Once you're finished, create a JPEG copy of the PDN to upload to your website to reduce load time and bandwidth consumption.

[Get A Trip]

Thanks Mountain Man. The only thing I could account for this 72 being cleaner looking than the 300 dpi is it had far less to shrink. In other words I was taking like 3000 by 2000 size down to the 300 by 200 size which is a huge size drop. That is with the 300 dpi. With the 72 dpi it started off as a 450 by 300 and dropped to a 300 by 200, only a few sizes down.

Taught me a hard lesson. I always think that bigger is better and that more is always better. Because when you go through agencies like IStock or ShutterStock they let you choose which size to down load all for the same price - at least with subscriptions they do. So I downloaded everthing huge as possible. Now I have 7 days left in my subscription to re-download almost 750 pictures. Crazy! Like they could of had a little tutorial prior to selling us a subscription or something. But in the end its all good because they will load faster on my websites which is their final resting place.

See you around--

Terry

[Get A Trip]

Simon, that was a great tutorial and plugins. haven't downloaded them yet but will as soon as I can. I am getting ready to re-watch the tutorial with a friend here, so thanks again. It was on target to my question and what I needed to know.