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Question about extra-large JPG

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ayryq:
OK, this doesn't really belong on this forum at all, but I couldn't think of a better community to ask.

I was going through wedding pictures from 2005 and found one that didn't make sense. The first image in a directory (titled 0000.JPG) is 120.9 MB. It opens fine and contains a picture from our wedding, 1536x1024. If I open and resave it in GIMP I get a 358 KB file (at 90% quality). The rest of the images in this directory are in the 6-8 MB range, and have the same dimensions.

SO, I was wondering if anyone could tell me
1. Why are all these 1.5 MP pictures so big?
2. Why is the first one even bigger?

Our photographer was an amateur and she had a failure with her CF card; we lost all our reception pictures. If I recall correctly, she sent in her memory cards and someone did some recovery on them.

Any ideas or leads? Would uploading the image help you help me?

Thanks, DCers.
Eric

IainB:
Whilst I could not answer your Qs, from what you said I would suggest that you go for inspection/analysis - e.g., open up the images using IrfanView, or PhotoME, which can tell you quite a lot about image compression levels, sizes, aspect ratios, EXIF and IPTC data, camera details, etc.

Though I have not recovered images from CF cards, I have recovered deleted images from old hard drives, and the recovered files tend to be uniformly very large (much larger than their original size would have been), and I think that may be attributable to some of the .JPG compression ratio data being lost, so you would probably need to resample or recompress them to get the file size down - I'm not sure if that would be a lossy process, but I suspect it could be.

Sorry I can't offer anything more than that.

Eóin:
Some quick multiplication says that a 1536x1024 image at 32bit colours (4bytes) would be 6mbs in size. So those smaller images are likely just in an uncompressed, or lossless compressed, format. Maybe it's to do with the recovery, or maybe the camera was just set not not compress the pictures to preserve the full original quality.

ayryq:
I opened both 0000.JPG and another picture (0005.JPG, 7MB) in Phatch Image Inspector. Neither has any EXIF or IPTC information (or Pil, Pexif or Zexif). Apart from the filesize, they appear identical.


--- Code: Text ---aspect        nonecompression   nonedpi           72filesize      126791680 [6979584 for 0005.JPG]format        JPEG (ISO 10918)gamma         Noneinterlace     Nonemode          RGBsize          (1536,1024)transparency  Nonetype          JPG

ayryq:
If anyone is ambitious/bored enough to look at these:
http://ericandchar.com/dc/0000.JPG [the big one]
http://ericandchar.com/dc/0001.JPG [a normal one]
http://ericandchar.com/dc/0065.JPG [one that doesn't work]

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