Last modified: 2014-05-23 16:15:43 UTC

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Bug 3892 - EXIF data shown incorrectly for fractional values
EXIF data shown incorrectly for fractional values
Status: NEW
Product: MediaWiki
Classification: Unclassified
File management (Other open bugs)
1.17.x
All All
: Low normal (vote)
: ---
Assigned To: Nobody - You can work on this!
http://commons.wikimedia.org/wiki/Ima...
:
Depends on:
Blocks: exif
  Show dependency treegraph
 
Reported: 2005-11-06 14:26 UTC by Daniel Kinzler
Modified: 2014-05-23 16:15 UTC (History)
4 users (show)

See Also:
Web browser: ---
Mobile Platform: ---
Assignee Huggle Beta Tester: ---


Attachments
var_dump() of array read from the file via exif_read_data() (2.69 KB, text/plain)
2005-11-09 22:11 UTC, Brion Vibber
Details
Attaching linked image to make sure it doesn't disappear. :) (241.33 KB, image/jpeg)
2009-05-26 21:25 UTC, Brion Vibber
Details

Description Daniel Kinzler 2005-11-06 14:26:54 UTC
The values for EXIF fields that are given as fractions are computed incorrectly.
Some examples for BumpassHell_8328.jpg (see link):

* F Number: shown as 0.979034803375, should be 7.2; given as 72/10 according to
jhead.
* Shutter speed: shown as 0.97903487118, should be 9.65625; given as 309/32
according to jhead.
* Aperture: shown as 0.914085909977, should be 5.71875; given as 183/32
according to jhead.

Interrestingly, the first two wrong values are the same for seven digits after
the decimal point (0.9790348), but different after that. The last one is also
relatively close, but not that close.
Comment 1 Walter Siegmund 2005-11-06 16:46:23 UTC
Also, the field "Date and time of data generation" is displayed as "15:41, 6 November 2005", i.e., 
apparently the current date and time. I think it should be "2005.10.25 12:56:28". That is when I 
took the image. See dump of BumpassHell_8328.jpg below.

The image was processed on an iBook (OS10.3) using GraphicConverter 5.7.1. If there is a bug in 
GraphicConverter, it would be helpful to have a short description so that I can submit a bug 
report (http://www.lemkesoft.com).

0000000  377 330 377 340  \0 020   J   F   I   F  \0 001 001 001  \0 264
0000020   \0 264  \0  \0 377 341 036   f   E   x   i   f  \0  \0   I   I
0000040    *  \0   6 034  \0  \0   C   a   n   o   n  \0   C   a   n   o
0000060    n       P   o   w   e   r   S   h   o   t       S   1   1   0
0000100   \0 264  \0  \0  \0 001  \0  \0  \0 264  \0  \0  \0 001  \0  \0
0000120   \0   2   0   0   5   :   1   0   :   2   5       1   2   :   5
0000140    6   :   2   8  \0 001  \0  \0  \0     003  \0  \0   H  \0  \0
0000160   \0  \n  \0  \0  \0   2   0   0   5   :   1   0   :   2   5    
0000200    1   2   :   5   6   :   2   8  \0   2   0   0   5   :   1   0
0000220    :   2   5       1   2   :   5   6   :   2   8  \0 003  \0  \0
Comment 2 Brion Vibber 2005-11-09 22:11:37 UTC
Created attachment 1054 [details]
var_dump() of array read from the file via exif_read_data()

The data as read from exif_read_data() is consistent with the output, eg:
  ["XResolution"]=>
  string(21) "1124073500/1852796513"

(Tried with PHP 5.0.2, 5.0.5, and 5.1.0RC4)
Comment 3 Daniel Kinzler 2005-11-09 22:44:43 UTC
so, this is another PHP bug, i assume? 

Hm... may this be byte order related? JPEG itself uses Motorola byte order,
afaik, but I don't know about the EXIF data contained.
Comment 4 Brion Vibber 2005-11-09 22:50:02 UTC
Not too sure, but I did get the same results running the function on
my Mac as on my PC.
Comment 5 Daniel Kinzler 2005-11-09 23:43:42 UTC
When I try extracting EXIF data from that image using PHP 4.3.8 (cgi) (built:
Jul 16 2004 08:32:27), I get a bunch of errors, and all the fields that return
garbage on the commons do not appear in the resulting array at all. Here are a
few of the errors i get:

  Warning:  exif_read_data(BumpassHell_8328.jpg): process tag(x829D=FNumber   
): Illegal pointer offset(x004F < x826252A)
  Warning:  exif_read_data(BumpassHell_8328.jpg): process
tag(x9201=ShutterSpee): Illegal pointer offset(x0087 < x8262572)
  Warning:  exif_read_data(BumpassHell_8328.jpg): process
tag(x9202=ApertureVal): Illegal pointer offset(x008F < x826257E)
  Warning:  exif_read_data(BumpassHell_8328.jpg): process
tag(x9003=DateTimeOri): Illegal pointer offset(x0057 < x8262542)

Apperently, PHP chokes on this file really bad...
Comment 6 Brion Vibber 2009-05-26 21:25:45 UTC
Created attachment 6156 [details]
Attaching linked image to make sure it doesn't disappear. :)

Just attaching the image for reference. Bug still visible on Commons.

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