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Leica M (240) Image Unique ID


biogon

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Hello everybody!

 

Apparently Leica in the M has changed the way of numbering shots in the "Image Unique ID" field of the exif data, the M8/M9 Hexadecimal numbering is no longer being used. Now we have there what appears to be a random decimal number, not correlated with the number of shots taken by that camera.

 

Does anyone know whether that number is really random (not completely because it should anyway remain unique, I surmise), or a hidden code exists allowing to tell how many shots the camera has taken?

 

Thank you and all the best.

Edited by biogon
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I don't really know the answer to your question as far as shutter actuations, but you could actually do the same thing with the M9 with a little workaround: you just had to renumber a picture on the SD card in your computer, then continue shooting with the M9 and it would follow in consecutive numbers for file naming after this last renumbered picture.

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Biogon......

 

You are quite correct ..... and the behaviour is not quite random.....

 

I seems to reset every time the camera is switched off (or possibly in standby too)..... and then produces unique id's with rising numbers but not in any sensible sequence starting at some random point ranging from the low thousands to several millions......

 

eg... (pic then unique id)

 

170 2274331

171 2314332

172 2388281

173 2435851

174 2537540

175 2601900 etc

 

next day:

 

207 95847

208 219539

209 404396

210 564961 etc

 

today:

 

233 6280

234 119385

 

camera off

 

235 37013

236 67552

237 143641

238 226094 etc.....

 

there is another number in the exif - unique raw id ......

 

but that has a basic form of 30303030303030x3x3x3x3x3x.....

 

where the x bits are in fact the image unique id (ie all the alternate 3's stripped out)

 

...... so you are correct .... without a degree in cryptography it looks impossible to tell how many actuations a camera has had........

 

.... and there is some sense in that ...... I returned my 'as new' ex demo M9 when I discovered it had in fact over 5000 actuations recorded .... which I argued made it 'second hand' ....... and got a new M9 for my trouble......

 

very interesting......:confused:

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Oh, thighslapper, now you have done it - teased a decoder. :)

 

The numbers past the sequence # cannot be pseudo-random for a number of reasons besides the fact that they are tied to the system hardware. For one, they increase with each new sequence # from power-on. Someone with more time and brains that I have will figure it out.

Edited by pico
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A BIG clue........

 

I fiddled about with this camera when I got it and reset the numbering to be 400Leica as the start folder and numbering to start from 4000001.... (so the numbers are unique and don't double up on previous M's)

 

This file has NO EXIF unique RAW id

 

The unique file id however is 00000000000000000000000000002cd1

 

no other alphanumeric coding features in any subsequent exif file id info.....

 

this one presumably seeds the whole of the subsequent numbering process....

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2cd1 hexadecimal in a M8/M9 body would correspond to 11473 shots. Is that number a reasonable estimate of the pictures you have already taken with your M 240 thighslapper?

 

What happens if you restore the default folder/numbering? The camera would resume generating semi-random decimal IDs, or will retain the hexadecimal numbering system?

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Could a date be being incorporated into the unique ID or alternatively, could this be linked to the GPS function, which will become available when the multifunction grips start to arrive? I was thinking that the unique ID = shutter actuation number + hexadecimal date (with start point ???)

 

Wilson

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apologies folks ....... 2cd1 is picture no. 1 when I reset everything and set up my own folder with my own numbering. It was an M9 image I copied to the card and renumbered to seed the numbering sequence ......... and in fact it did this as per the behaviour of the M9

 

The original date on the first few pictures was 2008 (I forgot to set it) .... and I again I reset the time a day later (I was 12hrs adrift as I hadn't set it to 24hr clock) and it seems to make no difference to the pattern of numbering.....

 

I am not going to restore the default numbering to investigate further ........ there are a number of glitches in the way the system works ..... the main one being it works independently for each camera profile .... and when I did this before it resulted in me having to re-enter everything for each profile and then take a load of blank pictures to bring me up to my original numbering ..... you would have to fiddle with this camera to understand how this works .... but basically the file folder and file numbering is not a global setting....

 

We need someone who is a mathematician to explain how you can set up an apparently random numbering system that will always produce unique numbers ....... date and time seems a bit flaky as you could reset the cameras time/date ..... unless it registers elapsed time since 'birth'.

Presumably there is some loook up table that provides a multplier or offset that generates the final number........

 

Although the numbers seem to rise when in continuous use the jumps are pretty random .......

 

I will post some screenshots of the full exif data later and see if someone spots something.....

Edited by thighslapper
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exif data :

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My question arose from looking at the exif data of some of the dng pictures posted by Ming Thein (Flickr: mingthein's Photostream), I do not own a M 240 (yet! ;)). In case they would help, I am listing their image numbers and corresponding Image Unique IDs below:

 

10 79393

22 754035

26 270199

27 344698

37 106609

41 123032

58 1014633

79 298026

85 313374

88 4718

95 517834

108 617410

111 194886

217 488822

249 424922

253 94525

278 523946

280 108239

282 45770

295 428897

305 276703

325 245075

334 179411

346 185423

362 421215

364 543819

373 260589

422 335311

429 316729

437 423110

438 491976

444 879230

457 531080

498 1845810

548 318712

563 319833

584 76126

733 117764

1273 114473

1336 506172

1348 761738

1362 869199

1364 90199

2115 78763

2230 164980

2250 154542

2423 458802

2505 455409

2532 74702

2887 926509

3101 259258

3108 218801

3143 2154800

3155 59695

3458 2564511

3492 4822417

3517 6475792

3532 90915

3539 559744

3641 2029507

3792 396759

3828 811918

4436 182029

4443 643539

4497 638831

4609 69941

4662 343922

4666 128843

4678 858528

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My question arose from looking at the exif data of some of the dng pictures posted by Ming Thein (Flickr: mingthein's Photostream), I do not own a M 240 (yet! ;)). In case they would help, I am listing their image numbers and corresponding Image Unique IDs below:

 

10 79393

22 754035

26 270199

27 344698

37 106609

41 123032

58 1014633

79 298026

85 313374

88 4718

95 517834

108 617410

111 194886

217 488822

249 424922

253 94525

278 523946

280 108239

282 45770

295 428897

305 276703

325 245075

334 179411

346 185423

362 421215

364 543819

373 260589

422 335311

429 316729

437 423110

438 491976

444 879230

457 531080

498 1845810

548 318712

563 319833

584 76126

733 117764

1273 114473

1336 506172

1348 761738

1362 869199

1364 90199

2115 78763

2230 164980

2250 154542

2423 458802

2505 455409

2532 74702

2887 926509

3101 259258

3108 218801

3143 2154800

3155 59695

3458 2564511

3492 4822417

3517 6475792

3532 90915

3539 559744

3641 2029507

3792 396759

3828 811918

4436 182029

4443 643539

4497 638831

4609 69941

4662 343922

4666 128843

4678 858528

 

Where is Alan Turing when you need him?

 

Wilson

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Could a date be being incorporated into the unique ID or alternatively, could this be linked to the GPS function, which will become available when the multifunction grips start to arrive? I was thinking that the unique ID = shutter actuation number + hexadecimal date (with start point ???)

 

Wilson

 

It seems unlikely that there's a date in there. I'm quite familiar with a few date coding methods, for example those that store a date as seconds since Jan 1, (whatever year). It is not HEX, either.

 

thighslapper: We need someone who is a mathematician to explain how you can set up an apparently random numbering system that will always produce unique numbers

 

That's 'random without replacement' and it can be done, and part of the sequence will reveal the technique.

 

....... date and time seems a bit flaky as you could reset the cameras time/date ..... unless it registers elapsed time since 'birth'.

 

hundredths of a second (or clock ticks) since manufacture is a cool idea, however some of the numbers are too small to be date/time.

 

Biogon - thanks for going through the trouble of gathering the new numbers, but it would help a great deal if they were perfectly sequential.

Edited by pico
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Biogon - thanks for going through the trouble of gathering the new numbers, but it would help a great deal if they were perfectly sequential.

I agree. But as I said I do not own a M 240, and those numbers are all I could get a few days ago from the Ming Thein's site.

 

Any other M 240 owner willing to contribute to the M240 cryptanalysis?

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I agree. But as I said I do not own a M 240, and those numbers are all I could get a few days ago from the Ming Thein's site.

 

Any other M 240 owner willing to contribute to the M240 cryptanalysis?

 

What do you want?

 

Wilson

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Perhaps someone could ask the nice Leica people in Solms .........

 

There seems to be a determined effort at obscurity here ..... so I doubt they will reveal all.... but they might divulge the rationale behind why they have done this..... :rolleyes:

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  • 4 months later...
Biogon - thanks for going through the trouble of gathering the new numbers, but it would help a great deal if they were perfectly sequential.

 

Hello, I resurrect this thread because I finally found a list of sequential Image Unique ID from M Typ 240 pictures (only No. 5 is missing because it corresponds to a video file).

 

https://dl.dropboxusercontent.com/u/100811023/M240_IUIDs.txt

 

I look forward that they may help in deciphering the mystery...

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  • 1 year later...
Guest JonathanP
and the behaviour is not quite random.....

 

I seems to reset every time the camera is switched off (or possibly in standby too)..... and then produces unique id's with rising numbers but not in any sensible sequence starting at some random point ranging from the low thousands to several millions......

 

I think you're correct. Sampling some of my images I think the number is time from camera switch on, incremented at a rate around 1500/sec. I haven't ascertained yet if the count continues whilst it sleeps, but switching off seems to reset it.

 

I know its nice to speculate that there's a clever scheme here to encode the shutter count, but come on - we're talking Leica software engineering. All they need for the ImageUniqueID exif tag is a number with a reasonable chance of not being duplicated - why not just sample an internal processor tick count at some point in the image taking process? They haven't even bothered to store the number in non-volatile memory to carry on when next switched on, which given the size of the field would have pretty much guaranteed uniqueness.

 

I'm sorry but Leica doesn't have a track record in software excellence, so my money's on the under-engineered, get away with the minimum possible solution ;)

 

Jonathan

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I'm sorry but Leica doesn't have a track record in software excellence, so my money's on the under-engineered, get away with the minimum possible solution ;)

 

+1

 

A proper algorithm would use:

 

- Camera serial number (unique globally - all Leica cameras).

- Shutter count (unique locally - your camera).

 

And given the fact I see in this thread a "663" number reported by biogon, it is extremely unlikely that Leica "engineers" are doing anything like that.

Edited by CheshireCat
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