JPG Image Size & Internet

[Rhobes]

Hi All-

I can't recall where but I heard or read that resizing eg a 300ppi file to 72ppi for net use is not necessary anymore, but I don't remember the reason why. Can anyone tell me if that is true to a certain extent and why?

I can say for myself that the two (a 300ppi file & a 72ppi file) will download at the same rate on my system. But, I know there are times it may not download a large jpg as fast as other times, yet infrequently.

I know your sending more file then the monitor uses but if a 300 vs a 72ppi pic opens at equal speed is there reason to re-size images every time you send one?

I have been told, "lets not pollute the Internet with large ,jpg files that are meant for hi-res Printers. More detail is just a waste of bandwidth." Is that a true statement? Is sending eg. a 240ppi pic to someone misuse of the internet? polluting it?

Thanks for your comments.

 

[Laird Knox]

PPI, DPI and LPI do not have any impact on your files size. If your image is 2000 x 3000 pixels then it is 2000 x 3000 pixels at 72, 300 or 44,000 PPI. If you ask a browser to display it it will be 3000 pixels wide.

Depending on the use and web site I typically constrain my images to between 400 and 800 pixels wide. Yeah, but at what DPI? I don't know. I never pay attention to that as it doesn't impact the display.

Note: The new retina displays may change this slightly. I have not worked with one yet and am not sure of the ramifications.

 

[ChrisA]

Hi All-

I can't recall where but I heard or read that resizing eg a 300ppi file to 72ppi for net use is not necessary anymore, ...

You heard right. the PPI setting is almost universally ignored. and all it is, is just a one number in the file header someplace. For photos headed to the web it is a useless setting.

All that matters is the total number of pixels and the "quality" setting. The amount of compression makes a huge difference in size of the file and is controlled by the "quality" setting when you save the jpg file.