JPG Image Size & Internet

Discussion in 'Digital Photography' started by Rhobes, Jun 27, 2013.

  1. Rhobes, Jun 27, 2013
    Last edited: Jun 27, 2013

    Rhobes macrumors 6502

    Rhobes

    Joined:
    Oct 28, 2004
    Location:
    Missoula,MT
    #1
    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.
     
  2. Laird Knox macrumors 68000

    Joined:
    Jun 18, 2010
    #2
    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.
     
  3. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #3
    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.
     

Share This Page