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Thread: JPEG file loses resolution on MOVE (IV 4.38/Win7Pro64)

  1. #1
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    Exclamation JPEG file loses resolution on MOVE (IV 4.38/Win7Pro64)

    Reviewing thousands of photos from a trip to Italy, I was sorting them into Best/OK/Bad directories using the "Move" hotkeys (F7).

    When I looked at the files, I notice the sizes had changed on the moved files! (JPEG only - not the RAW files)
    BEFORE: 7.93 MB (8,317,440 bytes)
    AFTER: 7.08 MB (7,427,796 bytes)

    So it lost almost 20% of the file!

    Visually, it is not obvious what changed, as the files are 16MP files, and to bring 2 up on a monitor reduces the resolution too much to tell anything side-by-side.

    This happened on pretty much every file.

    These were images from a Panasonic Lumix GX7 - not sure if that would matter.

    Computer is Windows 7 Pro/SP1, 64-bit, with 8GB RAM, 4-core CPU, with not much else going on.
    Very repeatable.
    IrfanView 4.38.
    Here is a sample pair (before & after) (UPDATE: added RAWs, which do NOT change):
    https://dl.dropboxusercontent.com/u/...ost%2BRW2s.zip

    What's going on?
    Last edited by toyzrme; 10.03.2015 at 11:32 AM.

  2. #2
    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    I cannot reproduce the problem by moving your original image to another folder using IrfanView.

    There are minor differences between the Exif data of the two images, but not enough to account for the big size difference.

    The information dialogue shows the same number of pixels, colours, and estimated compression for both images.

    I think you did something more than just move the files. Maybe you resaved the moved image?

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    Quote Originally Posted by Bhikkhu Pesala View Post
    .....
    I think you did something more than just move the files. Maybe you resaved the moved image?
    I was literally just going through the images in a directory using the arrow keys. I had created rating directories, (1-5) and assigned them to the different keys (slots) in the move dialog (1-5), to make it easy & fast to sort/rate them.

    So it was literally:
    <Rt-Arrow>
    <F7>
    1/2/3/4/5
    repeat....

    Could there be LOTS of EXIF stuff hanging off the end that's getting dropped? Although that doesn't make sense, as this should be a MOVE operation, which in Windows is just directory operations - i.e. it's not copying bytes, so shouldn't be able to lose them. FYI the source & destination directories were on the same disk.

    The files were originally copied off of a 64GB SD card, using Windows as well as Beyond Compare, to the "master (source) directory". I did a byte-by-byte verification to ensure the files had been copied off accurately, so that they are backed up to the cloud correctly. So the file sizes were correct (i.e. the larger version) after that copy - so it's more than one file system that thinks it's the larger number.

    My system also shows the same pixels & dimensions, and the images are all viewable, so it's not corrupting the JPG data. *or* it's re-compressing them - which doesn't make sense (btw, I don't trust the compression, as 2 vendors' implementation of a "9" could differ - as I remember, Adobe switched to a 12-point scale? But not 100% sure here...)

    I can say it's not every file that this happens to, but certainly > 20-30%. IIRC, it was repeatable on the same files.

    Very confused....would love to have Irfan weigh in, knowing the code and image storage way better than I do :-)

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    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    Irfan Skiljan doesn't post here. Send a bug report to him if you can reproduce it easily.

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    Multiple User Jacal's Avatar
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    I have no idea what went wrong here; the metadata in the second image have been changed and possibly corrupted, triggering some exiftool (minor) warnings. Exif byte order was changed and multiple face detection and face position tags were added. And even something about baby age. With metadata removed, the size difference is only 10 bytes.

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    Hi, did you use any other image viewer between copying the files from the SD card and moving it? I know that the Microsoft Viewer will save pictures if you use it to rotate the images. And on this step the images will be recalculated so there is no JPEG lossless opertation at this step. Maybe other tools will do like MS. Regards Nils

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    @derniwi - nope - just IV, in the process listed above, then checked the size. I do software development, so I know to reduce it down to the minimum to isolate the problem. Nothing else in the path - just copy from SD card, then review & move pics in IV as above.

    @Jacal - not clear from your post - did you try the posted files and experience the problem yourself? If so, I'll send a bug report to Irfan.

    Which version of the picture had the weird tags, the original/older one? Note that these images are from a Panasonic Lumix GX7 - could that be the source of the tags? But why would IrfanView get involved in the tags when doing a MOVE? Is it actually processing the tags?

    I've updated the link(s) to include JPG + RAW. The JPGs are straight from the camera, copied at the same time as the RAWs, and in the same directory (i.e. I didn't create them manually from the RAW files, the camera produced them). Note that the RAW files do NOT change size, only the JPGs.

    Here is something I found on Panasonic file tags - are these what you found? (I see baby age in there)
    http://www.sno.phy.queensu.ca/~phil/...Panasonic.html
    http://www.sno.phy.queensu.ca/~phil/...asonicRaw.html

    Sample: JPG + RW2 RAW files: https://dl.dropboxusercontent.com/u/...ost%2BRW2s.zip
    Last edited by toyzrme; 10.03.2015 at 11:31 AM.

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    Sorry, I was unclear; I wasn't able to reproduce your problem and can't imagine what caused it. I will look at your files later, have a nice day!

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    The new/modified meta data contains information about "Microsoft Photo". Sure, that you did not use this software? Maybe you have installed MS Photo (or MS Live Photo Gallery) and your destination folder is checked for pictures and face recognition?
    Last edited by derniwi; 10.03.2015 at 01:50 PM.

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    Multiple User Jacal's Avatar
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    And one more question: the two instances of your before.jpg (from your first and second link) are equal, but the timestamp of the files is different:
    File Modification Date/Time : 2014:04:30 21:53:40+02:00
    File Modification Date/Time : 2014:04:30 16:53:40+02:00
    Did you make this 5-hour change or is something fiddling with your files in the background?

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