www.ShoppingPodder.com

Leading Computer Shopping,
News and information
Part of the Identityscape.com network...

getxfactor.com jmoodmusic.com smartbusinesschoices.com mintdepot.com lowfaresalways.com evangelicalview.com shoppingpodder.com soproudlywehail.com webnews.ws currenthumor.com

 

 

extracting jpg files from a bundled package
   Shopping Podder - the Best of Computer Postings! Forum Index -> Computer Compression  
View previous topic :: View next topic  
Author Message
sobriquet
Guest
PostPosted: Thu Oct 23, 2008 5:14 pm    Post subject: extracting jpg files from a bundled package Reply with quote
Hello.
On an art cdrom, the graphics are jpgs that are bundled somehow. Does
anyone know how to unbundle them or extract the individual jpg files
from the package?

An example data file is here:

http://www.ibbu.nl/~nsprakel/combY


Simply renaming it to combY.jpg and opening it with irfanview will
display the first image in the package.

Kind regards and thanks in advance for any suggestions, Niek
Back to top
mathieu
Guest
PostPosted: Fri Oct 24, 2008 7:42 am    Post subject: Re: extracting jpg files from a bundled package Reply with quote
On Oct 23, 7:14 pm, sobriquet <dohduh...@yahoo.com> wrote:
Quote:
Hello.
On an art cdrom, the graphics are jpgs that are bundled somehow. Does
anyone know how to unbundle them or extract the individual jpg files
from the package?

An example data file is here:

http://www.ibbu.nl/~nsprakel/combY

Simply renaming it to combY.jpg and opening it with irfanview will
display the first image in the package.

I am on linux and non-of the usual tool did work for me :

Quote:
Kind regards and thanks in advance for any suggestions, Niek

Here is what I used:

$ wget http://www.ibbu.nl/~nsprakel/combY
$ file combY
combY: data

$ dd skip=108 bs=1 if=combY of=test.jpg
$ $ file test.jpg
test.jpg: JPEG image data, JFIF standard 1.01, comment: "AppleMark
\015ÿÛ"

$ jpeginfo test.jpg
toto.jpg 781 x 1090 24bit JFIF N 852248

The jpeg marker is at 0x6c AFAIK

2cts
Back to top
sobriquet
Guest
PostPosted: Sat Oct 25, 2008 5:58 am    Post subject: Re: extracting jpg files from a bundled package Reply with quote
On 24 okt, 09:42, mathieu <mathieu.malate...@gmail.com> wrote:
Quote:
On Oct 23, 7:14 pm, sobriquet <dohduh...@yahoo.com> wrote:

Hello.
On an art cdrom, the graphics are jpgs that are bundled somehow. Does
anyone know how to unbundle them or extract the individual jpg files
from the package?

An example data file is here:

http://www.ibbu.nl/~nsprakel/combY

Simply renaming it to combY.jpg and opening it with irfanview will
display the first image in the package.

I am on linux and non-of the usual tool did work for me :

Kind regards and thanks in advance for any suggestions, Niek

Here is what I used:

$ wgethttp://www.ibbu.nl/~nsprakel/combY
$ file combY
combY: data

$ dd skip=108 bs=1 if=combY of=test.jpg
$ $ file test.jpg
test.jpg: JPEG image data, JFIF standard 1.01, comment: "AppleMark
\015ÿÛ"

$ jpeginfo test.jpg
toto.jpg  781 x 1090 24bit JFIF  N  852248

The jpeg marker is at 0x6c AFAIK

2cts

I think there are supposed to be two jpg images in the combY file, but
I'm not sure if they actually use
a marker. Perhaps they have the filesizes stored as constants in the
program so they don't need
a separator code.

I have another example of a package that probably consists of more
jpgs here:

http://www.ibbu.nl/~nsprakel/combK
Back to top
mathieu
Guest
PostPosted: Mon Oct 27, 2008 9:54 am    Post subject: Re: extracting jpg files from a bundled package Reply with quote
On Oct 25, 6:58 am, sobriquet <dohduh...@yahoo.com> wrote:
Quote:
On 24 okt, 09:42, mathieu <mathieu.malate...@gmail.com> wrote:



On Oct 23, 7:14 pm, sobriquet <dohduh...@yahoo.com> wrote:

Hello.
On an art cdrom, the graphics are jpgs that are bundled somehow. Does
anyone know how to unbundle them or extract the individual jpg files
from the package?

An example data file is here:

http://www.ibbu.nl/~nsprakel/combY

Simply renaming it to combY.jpg and opening it with irfanview will
display the first image in the package.

I am on linux and non-of the usual tool did work for me :

Kind regards and thanks in advance for any suggestions, Niek

Here is what I used:

$ wgethttp://www.ibbu.nl/~nsprakel/combY
$ file combY
combY: data

$ dd skip=108 bs=1 if=combY of=test.jpg
$ $ file test.jpg
test.jpg: JPEG image data, JFIF standard 1.01, comment: "AppleMark
\015ÿÛ"

$ jpeginfo test.jpg
toto.jpg 781 x 1090 24bit JFIF N 852248

The jpeg marker is at 0x6c AFAIK

2cts

I think there are supposed to be two jpg images in the combY file, but
I'm not sure if they actually use
a marker. Perhaps they have the filesizes stored as constants in the
program so they don't need
a separator code.

I have another example of a package that probably consists of more
jpgs here:

http://www.ibbu.nl/~nsprakel/combK

$ strings combY | grep JFIF | wc
2 2 10

$ strings combK | grep JFIF | wc
10 10 50

Use an hex editor and look for JFIF (pretty easy). You'll see there is
a small header before each jpeg. So I would guess layout is:

main header (12 bytes):
01 00 00 0A 00 02 62 96 03 0F 04 15

for each jpeg:
108 - 12 = 96 bytes header per jpeg
then the first jpeg marker: ffd8

inspect the main header and you might find 2 or 10 encoded for the
number of files. and maybe you have the jpeg length encoded in the
'header per jpeg'.

good luck
Back to top
mathieu
Guest
PostPosted: Mon Oct 27, 2008 9:57 am    Post subject: Re: extracting jpg files from a bundled package Reply with quote
On Oct 25, 6:58 am, sobriquet <dohduh...@yahoo.com> wrote:
Quote:
On 24 okt, 09:42, mathieu <mathieu.malate...@gmail.com> wrote:



On Oct 23, 7:14 pm, sobriquet <dohduh...@yahoo.com> wrote:

Hello.
On an art cdrom, the graphics are jpgs that are bundled somehow. Does
anyone know how to unbundle them or extract the individual jpg files
from the package?

An example data file is here:

http://www.ibbu.nl/~nsprakel/combY

Simply renaming it to combY.jpg and opening it with irfanview will
display the first image in the package.

I am on linux and non-of the usual tool did work for me :

Kind regards and thanks in advance for any suggestions, Niek

Here is what I used:

$ wgethttp://www.ibbu.nl/~nsprakel/combY
$ file combY
combY: data

$ dd skip=108 bs=1 if=combY of=test.jpg
$ $ file test.jpg
test.jpg: JPEG image data, JFIF standard 1.01, comment: "AppleMark
\015ÿÛ"

$ jpeginfo test.jpg
toto.jpg 781 x 1090 24bit JFIF N 852248

The jpeg marker is at 0x6c AFAIK

2cts

I think there are supposed to be two jpg images in the combY file, but
I'm not sure if they actually use

byte 4 is actually the number of files: 0x02 and 0x0A match. You'll
need a package of more that 255 image to check how they encoded then
(need more than one byte).
Back to top
sobriquet
Guest
PostPosted: Tue Oct 28, 2008 6:31 pm    Post subject: Re: extracting jpg files from a bundled package Reply with quote
On 27 okt, 10:54, mathieu <mathieu.malate...@gmail.com> wrote:
Quote:
On Oct 25, 6:58 am, sobriquet <dohduh...@yahoo.com> wrote:



On 24 okt, 09:42, mathieu <mathieu.malate...@gmail.com> wrote:

On Oct 23, 7:14 pm, sobriquet <dohduh...@yahoo.com> wrote:

Hello.
On an art cdrom, the graphics are jpgs that are bundled somehow. Does
anyone know how to unbundle them or extract the individual jpg files
from the package?

An example data file is here:

http://www.ibbu.nl/~nsprakel/combY

Simply renaming it to combY.jpg and opening it with irfanview will
display the first image in the package.

I am on linux and non-of the usual tool did work for me :

Kind regards and thanks in advance for any suggestions, Niek

Here is what I used:

$ wgethttp://www.ibbu.nl/~nsprakel/combY
$ file combY
combY: data

$ dd skip=108 bs=1 if=combY of=test.jpg
$ $ file test.jpg
test.jpg: JPEG image data, JFIF standard 1.01, comment: "AppleMark
\015ÿÛ"

$ jpeginfo test.jpg
toto.jpg  781 x 1090 24bit JFIF  N  852248

The jpeg marker is at 0x6c AFAIK

2cts

I think there are supposed to be two jpg images in the combY file, but
I'm not sure if they actually use
a marker. Perhaps they have the filesizes stored as constants in the
program so they don't need
a separator code.

I have another example of a package that probably consists of more
jpgs here:

http://www.ibbu.nl/~nsprakel/combK

$ strings combY | grep JFIF |  wc
      2       2      10

$ strings combK | grep JFIF |  wc
     10      10      50

Use an hex editor and look for JFIF (pretty easy). You'll see there is
a small header before each jpeg. So I would guess layout is:

main header (12 bytes):
01 00 00 0A  00 02 62 96  03 0F 04 15

for each jpeg:
  108 - 12 = 96 bytes header per jpeg
  then the first jpeg marker: ffd8

inspect the main header and you might find 2 or 10 encoded for the
number of files. and maybe you have the jpeg length encoded in the
'header per jpeg'.

good luck

Thx a lot for your help. I think with a hex editor and a little
programming in prolog, I should be able
to obtain the individual jpgs.

Btw, the complete collection of artworks can be downloaded here:

http://thepiratebay.org/torrent/4473238/National_Gallery_Complete_Illustrated_Catalogue_CDROM
Back to top
Display posts from previous:   
   Shopping Podder - the Best of Computer Postings! Forum Index -> Computer Compression  
Page 1 of 1
All times are GMT

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum