Thumbnail to enlarged graphics file

[randem]

Anyone know of a free thumbnail to jpeg converter? I have pictures that are corrupt but the thumbnail is fine. How can I enlarge and create a graphics file from it.

[03myersd]

The thumbnail is stored seperate from the actual file on windows. The largest image you could get back would be by doing a screenshot of the thumbnail.

[randem]

Actually the thumbnail is inside of the JPG file and can be extracted. This is what I need. A screen shot of the thumbnail is too small.

[randem]

Ok, I found software that can extract the thumbnails and create jpg files. Now I need a program that can recreate the picture from the thumbnail. You see the actual picture file has been deleted and recovered and the thumbnails are totally intact but the picture is not. Since you can create a thumbnail from a picture I figure it can go the other way also... Of course accounting for some errors in enlarging but it should be ok within reason...

[mendhak]

Actually the thumbnail is inside of the JPG file and can be extracted. This is what I need. A screen shot of the thumbnail is too small.
I don't believe that is true. Thumbnails are created from the original image - by resizing. Once you have a thumbnail, in either case, you cannot go back to the original.

[randem]

Actually It is true, A thumbnail is just a smaller resized version of the original picture. So you can enlarge regular pictures so therefore you can enlarge Thumbnails... this has already been done.

Now accounting for errors in color, depth etc... You should be able to recreate the full picture within limitations. That is exactly how enlargements are made of regular pictures that are several to hundreds of times bigger than the original picture... The thumbnail is just a picture...

A reasonable facsimile is what is needed...

[03myersd]

Aren't thumbnails stored in the file thumbs.db? I thought thats what that file was for? Therefore if the file is corrupted you can only get the thumbnails back which are only (if I remember correctly) 96x96?

Edit:

That is exactly how enlargements are made of regular pictures that are several to hundreds of times bigger than the original picture...

Won't they be all pixelated then unless they are vector images?

[mendhak]

Actually It is true, A thumbnail is just a smaller resized version of the original picture. So you can enlarge regular pictures so therefore you can enlarge Thumbnails... this has already been done.

Now accounting for errors in color, depth etc... You should be able to recreate the full picture within limitations. That is exactly how enlargements are made of regular pictures that are several to hundreds of times bigger than the original picture... The thumbnail is just a picture...

A reasonable facsimile is what is needed...
Yes, the image gets resized so there is loss of information. Going from thumbnail to 'original size' will make the loss apparent and you'll have pixelation. You're willing to live with that in this scenario?

And I'm still going to disagree with what you're saying, because if it were indeed true, then data storage problems would be gone, since all images can be reduced to a tiny, 1kb size file and the 'large' version can get extracted as and when required. Imagine sites like picasa and flickr being able to run off a simple 1 terabyte hard drive.

When you say this is how enlargements are done, are you talking about in photo development stores in the real world, or do you mean on places like flickr.com where they have a thumbnail, small, medium and large size image? Keep in mind that the colors, depth and tone and all the extra metadata has to be stored somewhere.

Additionally, the thumb that I now think you're referring to is something that many phone cameras do - embedding the 'preview' version into the image itself, but this is gone and the cache is refreshed when the image's thumbnail gets refreshed, so it can be considered volatile.

I'd love to see an example of what you're talking about.

[randem]

The real problem is the pictures are corrupted so any picture is better than none... Since the thumbnail is intack, to recreate a larger picture from that is needed. Some is better than none if the pictures are important. A little color/depth lost is not an issue...

BTW: Windows creates the thumb file so that it wont have to scan the picture files to get the thumb nail each time you view the folder...

[03myersd]

BTW: Windows creates the thumb file so that it wont have to scan the picture files to get the thumb nail each time you view the folder...

So if you deleted this file and tried to view thumbnails it wouldn't work because the files are corrupted. If the files aren't too corrupted then you could try viewing them in infranview. It has saved a few midly corrupted pictures for me.

[randem]

You are missing the point...

Windows will view thumnails without that file. The files are too corrupted parts are missing. You can ONLY get the picture back from the thumbnail

[03myersd]

Windows will view thumnails without that file.


Yeah but in this case it can't because its corrupted? So the only place the thumbnail is left is in that file. As you said, windows scans the file every time it needs the thumbnail, which it can't do now.

[randem]

It can do that as I stated. That is not the problem... Never has been

[03myersd]

Im confused now.... The only place you can get the thumbnail from is the thumbs.db file?

[randem]

It is not you have to keep up... I explained that earlier...:p

[03myersd]

God I love working with the more experienced members of the forum. I saw a post the other day where someone was called very rude names by someone with a post count of about 2, just because they didn't understand what the OP was asking.

If the file is corrupt though then how can windows scan it to get the information for the thumnails? If you cant view the file then surely windows can't create a thumbnail from it? Otherwise you would be able to view it?

[mendhak]

There's a PDF with an explanation and a software mention in here that shows how you can extract data from your thumbs.db file.
http://www.acquisitiondata.com/white_papers/thumbsdbfiles.pdf

Assuming you're talking about thumbs.db.

[randem]

File file contains portions and pointers and an array of other information. In a block is missing from the middle of the file it does not affect the information in the beginning of the file so you can still read that information.

here is an example from a corrupt picture. As you will see all the header information is still intact.

[randem]

I am not interested in the thumbnail.db file. I couldn't care any less. Someone brought that file up and now the direction has turned to that file...

I don't care about that file it is meaningless to me...

[randem]

Please pay close attention to the part of the file noted as:

*** Embedded JPEG Thumbnail ***
Offset: 0x00000800
Length: 0x000011E2 (4578)

* Embedded Thumb Marker: SOI

* Embedded Thumb Marker: DQT
Length = 132
----
Precision=0 bits
Destination ID=0 (Luminance)
DQT, Row #0: 9 6 5 9 13 22 29 35
DQT, Row #1: 6 6 8 11 15 33 34 30
DQT, Row #2: 8 7 9 13 22 33 39 31
DQT, Row #3: 8 9 12 16 28 49 45 34
DQT, Row #4: 10 12 21 32 39 61 58 42
DQT, Row #5: 13 19 31 36 45 58 63 51
DQT, Row #6: 28 36 44 49 58 68 66 55
DQT, Row #7: 41 52 54 55 62 56 57 54
----
Precision=0 bits
Destination ID=1 (Chrominance)
DQT, Row #0: 9 9 12 20 15 26 79 79
DQT, Row #1: 9 10 12 10 26 26 79 79
DQT, Row #2: 12 12 10 10 26 79 79 79
DQT, Row #3: 20 10 10 26 79 79 79 79
DQT, Row #4: 15 26 26 79 79 79 79 79
DQT, Row #5: 26 26 79 79 79 79 79 79
DQT, Row #6: 79 79 79 79 79 79 79 79
DQT, Row #7: 79 79 79 79 79 79 79 79

* Embedded Thumb Marker: SOF
Frame header length = 17
Precision = 8
Number of Lines = 120
Samples per Line = 160
Image Size = 160 x 120

* Embedded Thumb Marker: DHT
Length = 418

* Embedded Thumb Marker: SOS
Skipping scan data
Skipped 3999 bytes

* Embedded Thumb Marker: EOI

* Embedded Thumb Signature: 01D91E583DD0037108266E42ED3A262C