Pics Transferred Options and Quality

Discussion in 'iPad' started by CanadianEh, May 10, 2010.

  1. CanadianEh macrumors member

    Joined:
    Jan 17, 2009
    #1
    Hi all, just one hurdle before committing to the ipad. When I transfer pics to my itouch, the picture quality is downgraded (or it looks to me that way). Does the ipad do the same? Is it possible to transfer directly from iphoto to ipad or would it have to go via itunes? Thanks.
     
  2. Bierp macrumors member

    Bierp

    Joined:
    Apr 19, 2010
    #2
    I've done some testing on this, though I haven't tested every possible iteration and there are a few tests I haven't gotten back to yet.

    I'm happy to share what I've determined so far. It should be noted that I don't have a Mac or iPhoto. My images were managed in Lightroom on my PC or directly from my Pentax K20d (14.6 MP).

    The short answer is that there seems to be some image reduction when synced through iTunes when using large files.

    For my test of this I imported several versions of the same image at different sizes. I was looking for the 'sweet spot' for making my images nicely viewable on the iPad without eating too much space.

    Image import info: (line counts represent pixel count of the long edge)

    RAW image (DNG Format) - 4672 lines - 23.1 mb
    JPG at full resolution - 4672 lines - 2.5mb
    JPG at half resolution - 2336 lines - 737k <-- this appears to be my sweet spot.
    JPG at 1600 lines - 400k
    JPG at 1024 lines - 240k
    PSD file at half resolution - 2336 lines - 20.6 mb, but the iPad does recognize and display Photoshop PSD format, which is cool.


    For comparitive testing on these, I zoomed in as far as the iPad would allow and compared the max zoom as well as the quality (jpg or other compression indicators).

    On the iPad, the max zoom and quality appeared to be nearly identical for the RAW, the full jpg, the 50% jpg and the 50% PSD. It dropped considerably for the 1600 and lower. This indicates to me that there is some compression happening for the larger files. Possibly a cap or something, but at a reasonable size...certainly well over 1600 lines.

    It's important to note that iPad seems to force you into an sRGB color space. (not a huge surprise here, but a factor to be sure.) I haven't completed all testing here yet, but comparing my RAW file to the jpgs in sRGB shows the distinct drop off of pinks in skin. I definitely have more testing to do on this.

    I have not conducted as thorough a test set on direct camera imports, but I can tell you that imported images are managed completely separately from synced images. You can use the iPad to store images in the field to download to your mac/pc when you get home. There is no filesize reduction using this method. I have not conducted the zoom test on imported files yet. Also, if you shoot a RAW+JPG and import it, it will flag it as both, and will save both on your iPad, but it will only display one in the import album. I have not determined yet whether it shows the RAW or the JPG and how compression affects this.

    There doesn't seem to be a way to tell if synced files are actually reduced in filesize. Jailbreaking might do this, but I won't be doing that.

    More to come if I find time to test.

    Hope this is somewhat helpful.


    B
     
  3. gillybean macrumors 6502a

    Joined:
    Jul 21, 2008
    Location:
    Seattle, WA
    #3
    If you want to avoid the quality downgrading, just upload the pic directly to GoodReader or Air Sharing HD. Then it'll keep the original file without modifying it.
     
  4. iRabbit macrumors 6502

    Joined:
    Jul 10, 2007
    #4
    Photos are resized to: 2304 x 1536 (if they are larger than that to begin with).

    They aren't "compressed" as much as on the iPhone/iTouch. The optimization algorithm seems better.

    If you use Aperture to do the sync instead, you can control how they are transfered (I don't do this, but that's what I've read).

    I'm big into photography and I've been pretty happy with how my photos look on the iPad overall. Not as good as at full res on a big color calibrated monitor... but certainly good enough.
     
  5. Bierp macrumors member

    Bierp

    Joined:
    Apr 19, 2010
    #5
    Thanks Rabbit. Looks like I stumbled pretty much right into it. Where did you get that number?



    B
     
  6. CanadianEh thread starter macrumors member

    Joined:
    Jan 17, 2009
    #6
    Thank you all

    :)

    Would video be downgraded as well?
     
  7. HiRez macrumors 603

    HiRez

    Joined:
    Jan 6, 2004
    Location:
    Western US
    #7
    That's odd, I wonder why not 2048x1536, double the screen dimensions?

    Edit: That's actually a 3:2 aspect, same as the iPhone. I wonder if they originally planned on a 3:2 screen instead of 4:3, or maybe it just depends on the source material and your photos happen to be 3:2. It might do double the size in the smallest dimension and the larger dimension is scaled appropriately.
     

Share This Page