Re: [Gimp-user] What causes random (in error) image color-inverting of TIFFs, over time? Is it correctable?

[Jay Smith <jay JaySmith com>]

> On Sun, May 31, 2015 at 4:25 PM, Jay Smith <jay jaysmith com
> <mailto:jay jaysmith com>> wrote:
>
>     Greetings fellow Gimp Users,
>
>     I make images using Gimp, but I assume that this question is not
>     really Gimp specific.
>
>     I have tens of thousands of images (postage stamps) on my site.
>     Every now and then when I am looking at a page I discover that the
>     image (a JPEG) has had is colors "sort of inverted".  The JPEGs were
>     created in large batches by a script from UNcompressed TIFF images.
>     When I go back and look at the the original TIFF, I discover that
>     its colors are "sort of inverted" -- thus the JPEG is a correct
>     rendition of the appearance of its TIFF source.
>
>     Thus the problem is in the TIFF.  But, the problem happens now and
>     then, over the course of years.  The TIFFs are _not_ being
>     intentionally manipulated in that time.  The images was originally
>     okay, now its not.  It seems to be completely random, just one image
>     here and there.
>
>     Somehow the TIFF is getting corrupted.  I am assuming by a memory
>     error or a disk/RAID controller error, or such.  The images are
>     still openable in Gimp.
>
>     This is only happening to one out perhaps one out of five thousand
>     images, every five years.  (I am just *guessing* at the error rate
>     because I only find out about them by randomly coming across them.)
>     But, if I have 40,000 images, that is eight images destroyed every
>     five years.  (And often I am not able to replace the image because I
>     no longer have the item.)
>
>     This example image was originally created in 2006.  I suspect
>     (mostly guessing) that it was corrupted sometime since 2010.  There
>     is no reason that it would have been edited since that time and file
>     modification information shows nothing since 2006.
>
>     On Ubuntu Linux, using "identify -verbose filename.tif" I can read
>     the header information.  The only odd thing (to my eye) is that the
>     create date is 2011 and the modification date is 2006:
>
>     Properties:
>          date:create: 2011-09-13T11:30:24-04:00
>          date:modify: 2006-12-21T00:53:03-05:00
>
>     I am guessing that means the corruption may have happened in 2011,
>     even though the filesystems own file datestamp is 2006 and the
>     lsattr command shows nothing unusual.
>
>
>     Here is example of a) the resulting JPEG (just to illustrate the
>     nature of the corruption); b) a similar JPEG to show generally what
>     it is supposed to look like; c) the corrupted TIFF.
>
>     Corrupted:
>     http://jsa.viewimage.net/jsa/web/Lists/Denmark/AdPairs/Spec/re02-pair_used-vf-b_136468_r_l.jpg
>
>     Correct image of a similar, but different item:
>     http://jsa.viewimage.net/jsa/web/Lists/Denmark/AdPairs/Spec/re02-pair_used-vf-a_136467_r_l.jpg
>
>     This is the TIFF file (corrupted, but viewable in Gimp; colors are
>     sort-of-inverted)  Size 496 KB:
>     http://jsa.viewimage.net/temp/gimp/re02-pair_used-vf-b_136468.tif
>
>     My primary question is whether there is a "particular bit that is
>     getting flipped" that could be "unflipped" by some sort of
>     non-visual editing of the source TIFF file?
>
>     My secondary question is whether or not other people have seen this
>     type of problem crop up in large image libraries and what the causes
>     have been?
>
>     Any thoughts appreciated.
>
>     Jay


On 05/31/2015 08:46 PM, Daniel Smith wrote:
> when you say youre seeing thison a web page,
> can i ask what type of system yure serving the pages with?
> wordpress etc? or is it an image generation with php or something?
> thanks
> dan


Hi Dan,

When I say I saw it on a web page, all I meant is that was where I was 
looking when I noticed the corrupted file (JPEG version thereof).

All viewing (of both the JPEG and the original TIFF that the JPEG was 
made from) after that time has been done using Gimp to view the 
corrupted files.

The fact that I first noticed the corrupted JPEG on a web page was not 
relevant and I should not have included that detail.  I only mentioned 
it that way because that is the only way I actually would notice that 
one of tens of thousands of files had been corrupted.  I don't 
systematically go through and view the library of files just for fun.

I am sorry for the misleading detail.

Jay