Monday, May 04, 2009

Apple's iPhoto and MobileMe photo blunder: when full quality isn't.

Adam Engst is far too kind to Apple in this article (emphases mine) ...

TidBITS Media Creation: How to Share Full-Quality Photos via iPhoto

A reader recently sent me email asking why sending a photo via email using the "Actual Size (Full Quality)" option in iPhoto resulted in a photo that was significantly smaller than the size of the photo within iPhoto...

A quick test on my system confirmed his results. My Canon PowerShot SD870IS's test photo started out at 3.1 MB and 180 dpi before dropping to 1.7 MB and 72 dpi. When I opened both the original and the reprocessed photos, Preview's inspector window showed the change in dpi and file size, though the dimensions of the photos were indeed identical.

... iPhoto always compresses photos sent via email to reduce the file size...

... posting the photo to your MobileMe Gallery won't help either, since iPhoto compresses uploaded photos there as well, even when you use the Actual Size option in the Advanced preferences for a MobileMe Gallery album...

... is an EmailCompressionQuality key in the file that's set to 0.75 ... When I bumped it up, the size of photos sent via email did increase, but when I set it to 1.0, the file size nearly doubled from the original....


Adam is glossing over some key points in an understandable effort to be sweet to Apple.

The problem is not that "iPhoto [always] compresses photos", it's that iPhoto is decompressing the original JPEG (SD870 is JPEG, not RAW), then recompressing it at a severe .75 JPEG compression factor. The decompression/recompression factor is why, when Adam moved the quality index to 1, the resulting JPEG was twice as big as the original. (You'll see the same thing with any image managed this way.)

This is a big deal for photo geeks. Try putting an image through four sequential JPEG 0.75 save/edit cycles and you'll get a mess. When I put "full quality" images on Picasa Web Albums or SmugMug one of the things I get is a high quality backup of my image. We now know that's not true of MobileMe -- it only looks that way.

The discovery that "full quality" images posted on MobileMe are being put through the same decompress/recompress cycle, while being sold as "full quality", ought to be red meat for a lawyer. Anyone know of a hungry lawyer taking charitable contributions for yet another Apple lawsuit? I don't care about winnings, I just want them to suffer.

For my part I'm going to give this a try with Google's Picasa Web uploader and see what I get back. I don't use MobileMe, and I'm not likely to start now.

Incidentally, a more subtle version of this stupidity occurs in Aperture. If you import a JPEG image into Aperture, don't apply any edits, then export it from Aperture using a standard JPEG setting with quality 1 you'll see the same (pointless) decompression/recompression at work.

Update 5/26/09: Apple doesn't apologize, but it effectively confesses to the blunder. No promises of a fix, however.


Anonymous said...

Gordon, please post when you determine the best way to share true full quality. I have the same Canon SD880 IS and a Rebel which I often use RAW format.

For best quality printing, I was emailing one pic full quality. The last time I sent a CD with file as any export from iPhoto was smaller. Now I need to determine a better method for emailing and uploading full or original quality.

I am wondering if Adobe Lightroom wouldn't be a better solution, but combined with what service online? I use both iPhoto and Lightroom, but may switch to LR full time. It handles RAW better as I believe iPhoto converts to Raw when I try to export anyways.


Colin Purrington said...

This is so depressing. Just discovered this problem with my Aperture-exported mobileme gallery. I've been telling photo recipients that the uploaded version was original for months. Absolutely horrible that Apple has deceived us. Thanks for your post.