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Cropped? How to know?

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echelon2004 said:
You get the focal length from the exif, then you measure the scene (in real life), measure the image, triangulates and compares.
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You are getting into major forensics here, and unless you know the EXACT lens, EXACT focal length, then you'll not be able to do what you are thinking.

I'm also sure that there are enough variations in lenses to render this difficult.

Then what if you crop and then resize back? and what if person doing this has also performed lens correction (or even dilberate distortion - this is a legal case afterall)

Way too many factors, and if its only a small crop practically impossible to work out.
 
Hm you're probably right.

It might however be possible to reverse the demosaic process and compare with the original filter array. Or analyze the artifacts and see if they're consistent with the demosaic processing or if they match some of the methods for enlargment. That should be failry simple.

It would really help to know the exact issues here...
riddell said:
riddell said:
You get the focal length from the exif, then you measure the scene (in real life), measure the image, triangulates and compares.
Click to expand...
You are getting into major forensics here, and unless you know the EXACT lens, EXACT focal length, then you'll not be able to do what you are thinking.

I'm also sure that there are enough variations in lenses to render this difficult.

Then what if you crop and then resize back? and what if person doing this has also performed lens correction (or even dilberate distortion - this is a legal case afterall)

Way too many factors, and if its only a small crop practically impossible to work out.
Click to expand...
--
Anders

'It is nice to be important but it is more important to be nice'
 
you are full of advice for everyone!
--
Greg Gebhardt in
Jacksonville, Florida
 
tonymp said:
Only a RAW file is admissible in a court of law ( here in the UK at least)
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I'm not sure that is correct. Much would depend on the source and how important it is to the case. The fact is all evidence has to be backed up by testimony as to method of gathering and maintenance.

If the photographs in question are vital and the lynchpin of a case, even if they had been 'cropped', the photographer could swear in court or sign an affadavit that they had not been manipulated.

The particularly daft thing about the issue raised (eventually) by the OP when it comes to photogaphs in a legal setting is that the 'cropping' can be done at the time of taking the shot by simply framing to keep out any 'undesirable' elements with regard to one party or the other.

Furthermore, you would still need testimony as to the technical aspects of the photographic representation. As an example, a previous employer of mine (a very small woman) was assaulted in a shop by quite a large man. He used a photograph to dismiss her account of the events, explaining that she could not have held on to a particular shelf because it was too far away. The shot was taken with a wide angle lens and made the shop look huge! Unfortunately neither I, nor anyone else who could have explained, was asked to appear.
--
Get busy living, or get busy dying...
 
hi Greg,dont be angry couse i have long memory and i remember what you have wrote about GF1

but you havent told me if you have a second GF1 or its still the same you sold :-)))

ps yes my english skills are not so good, but i have learned without ever been in UK or USA, i doubt your italian or german is like my english ;-)
--
angel
 
hi Greg,dont be angry couse i have long memory and i remember what you have wrote about GF1

but you havent told me if you have a second GF1 or its still the same you sold ))

ps yes my english skills are not so good, but i have learned without ever been in UK or USA, i doubt your italian or german is like my english ;)
--
angel
 
Is this ass hole week? just answer the man
Court files should not be altered in any way

The photographer should have been told this and you should have in your possession the orginal camera card that was used. If you do not you may or may not get them thrown out of court as evidence. You should have a chain of custody report signed by everyone who has touched the card or pictures and thier personal information so they may be called to court to testify. Civil cases are not as strict as criminal and a lot depends on the judge. As long as it looks good it may be accepted. CROPPING IN ITS SELF SHOULD NOT GET A PICTURE THROWN OUT AS EVIDENCE AS LONG AS YOU CAN EXPLAIN WHY.

Do you have photo shop? If yes
load the picture file
go to file / file info
If the data is striped they will scream altered even if it is not altered

If the data does not match in pixel size to another fille. the file was altered by cropping.

If the file was dubed to a second layer in PS then resized and flatten to the same size as original. You will not know if it is altered.

If you compair two files taken of the same area by inlarging 300 percent in PS you will see more distortion in the cropped or adjusted file if the size has been altered a great amount
If it has been altered a tiny amount you will not see it.
 
Poorly asked question, but anyway...

If photos are cropped in a manner where the cropper is trying to mislead, it's pretty hard to tell.

Making me wonder how you saw something you thought was cropped. Indicates a pretty poor crook.

But for most images, it's easy to tell if cropping took place. assuming you know the kind of camera (in broad strokes) used.

Almost all digital single lens reflex cameras take photos in an aspect ratio of 3:2

So, open the file in Photoshop Elements, go to Image...resize...image sixze and see if the pixel count is the same for other pictures you believe are not cropped.

Plus, do some quick math to see if the height to width ratio is still 2:3.

Any normal photographer trying to serve a client by providing ood shots willdeliver files where this sytem works. A crook may manipulated with intent to deceive.

But your original question, and subsequent clarifications, are badly asked, careless, and not very helpful, as far as geting a proper answer goes.

BAK
 
I taught in the photojournalism field for many years, where image manipulation is considered a capital crime. You can lose your job for removing a zit. However, certain post processing is not considered unethical manipulation, including most procedures that were commonly done in the darkroom in the days of film: resizing the image, adjusting brightness, contrast and colour for best reproduction, minor dodging and burning, and cropping to concentrate the reader's attention on the subject.

Cropping is no more unethical than moving closer to the subject, or using longer glass, both of which produce the same final effect.
--
My photos on Photobucket:
http://s485.photobucket.com/albums/rr219/neilcrichton/
 
business report
includes date picutres were taken
location
time
weather conditions if needed

camera information, menu settings because I run plus 1 on contrast, sharpness and color

All files are in srgb jpg. untouched in any way. No files are deleted from the card even if they are bad. This insures that the pictures are numbered in sequence with no gaps. I give them no chance to ask where the missing picture is or why it was deleted
Chain of custody report information:
includes where pictures were printed.
Lab clerk signs this for me
Option of: I retain orginal card until case is over or I give them the card.

I make a copy DVD of all pictures and this is held until case is over. Note on report.

Every person that touches the card or prints before delivery to the client is on this sheet

I am prepared to go to court with a computer and PS to bring up the file information if needed. Always have my back up DVD if the card is challanged in court
I also will print out the file information for court if needed.
 
I get your point and I did consider this.

But its very easy to crop and then to resize the image to exactly the pixel resolution it was before.

If its only a minor crop I would think its near on impossible to tell. And as with my previous post, lens distortion, ISO levels and everything else would have a lot of baring at this point as to how difficult it would be to spot things.

Then don't forget the photographer could easily take a full res image in RAW, but then convert and crop and compress and then claim that he took the image using in camera .jpg at a lower resolution and with compression.

And again as before, don't forget a number of pro cameras can even write both formats / resolutions and compressions at the same time.
 
An uncropped image will have a given pixel size. My 5D2 in sRAW has an image size of 5616X3744.
If I crop at all in any way then that will change.

Vista can display the file size easily enough, so sort on that and you'll have a list of those that were cropped.

Even for PJ use cropping is normal to fit the column width in the paper, to get closer in, etc.

but whatever
 
neilcrichton said:
However, certain post processing is not considered unethical manipulation, including most procedures that were commonly done in the darkroom... and cropping to concentrate the reader's attention on the subject.
Click to expand...
Cropping was more often done on the back bench by page designers when on-screen page design came into being. They knew the size the picture had to be to fit the page.
--
http://calvininjaxfotos.wordpress.com/
 
A photograph does not necessarily represent reality. Never has and never will. Photojournalists like to delude themselves and hopefully everyone else that if the photo in question is unmanipulated that it represents reality. BUT, THEY ARE ONLY DELUDING THEMSELVES! And hope to delude others by their faith in the photograph as realiy. Photographs are entertainment and have no place in a court of law.
--
Packrat
I link, therefore I am!
 
Nope, JPEGS are quite often used by law enforcement in the UK. The data is transferred direct to CD (no computer) and introduced into the court via a witness statement written by the Officer that took them. Covers, dates, times and locations. The court will then be produced with an album of the selected images.

Regards
Christian

--
http://www.christianhough.com
 
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