Please explain somethings about digital photography

[Judge Sharpe]

Hello the campfire:
As some of you may know, I have over the past years used film, from 35mm to 4x5, and know next to nothing about digital photography.
My question: Hypothetically how would one add to or subtract from a digital photograph- such as adding a person to the picture or using a cloning program to take an unwanted object out? Can this be done both in RAW and JPeg? Is there a way to tell if a photograph has been "photoshopped" to use the popular vernacular?
I know these are basic questions, but I am not even a novice when it comes to digital photography, and have not been successful in finding out this information on my own.

 

[NateS]

I can't speak for everyone, but I use Capture NX to edit my RAW files and capture NX doesn't have tools such as clone, so I do this after I process the RAW. I usually get everything color/exposure/etc.....that I want right with the raw and save as a tiff.
Then I open the tiff in Gimp (or photoshop if you have money) if I need to clone something out. There's a very simple tool that just takes some experimenting to get right called the clone tool. Basically you select as certain section of the image that you want to use as the clone and then when you use the tool over whatever you are cloning it will replace the image with the first area you selected.

If done really well, you shouldn't be able to tell. Here's an example of a recent photo that I had to do a good bit of cloning on.

To the right of the duck (the duck's left), in the water behind him on that side, there was another duck's butt which distracted from the duck that I took the picture of.
I got rid of the other duck by cloning it out using a section of the water on the other side of the duck. Nobody probably noticed the first time I posted that photo, but I got a hair sloppy with one of the waves ( the lower black one on the right of the picture). I'll clean that up by running the blur tool over that black section so it blends into the water.

Hope that helps. Adding something into the photo and making it realistic is much harder since the two usually have different light sources/angles, tones, etc... which makes it hard to look realistic.

 

[Big Mike]

My question: Hypothetically how would one add to or subtract from a digital photograph- such as adding a person to the picture or using a cloning program to take an unwanted object out?

It's all in the software...with a program like Photoshop, things like that are fairly easy. Remember that a digital image is just a bunch of 'pixels' lined up together...each one having it's own color/tone designation. So when you add or subtract something...you are just reassigning certain pixels to display a different color.

Can this be done both in RAW and JPeg?

Again, it's the software. If you have software that allow for these edits on RAW images, then you can do that. A program like Adobe Lightroom, can 'edit' RAW files...but it really doesn't 'change' the RAW image...it records the changes and applies them only when you output the file.
JPEG is a standard file type and is basically just the pixels...so you can do anything to it.

Is there a way to tell if a photograph has been "photoshopped" to use the popular vernacular?

Sometimes it's easy or obvious, just by looking at it. Sometimes there is embedded information in the file, that can be read and maybe that could be used to tell if an image is direct from a camera or if it has been edited.

 

[Judge Sharpe]

Thank you for your quick replies. You have confirmed what I thought. Sometimes it becomes important to assure that the photograph one sees actually depicts the scene as it existed back when. I am trying to come up to speed on newer technology as it relates to a particular part of my profession. For a long time it was assumed that what you saw was what you got in police crime scene photographs, now I a not so sure. Not that I distrust the police, and I hope that I do not offend anyone, but in many of my cases, the little things are the jewels that the case revolves on and I want a clean record for someone facing the ultimate penalty. Sometimes I feel that I am too old for this work and sometimes I think that I would not wish it on a young person because it certainly darkens ones life after a while. Photography, properly attempted, requires enough though that I can put certain demons behind me for a while Thanks again
Judge Sharpe

 

[The_Traveler]

I saw a swan like yours but different.

 

[Garbz]

The blackhats recently showed off a utility that can identifiy the quantisation of the jpeg algorithm and how it relates to various programs. They showed with significant certainty that a photo straight of the camera saved as jpeg can be told apart from the photoshop file even if it was only opened and then saved again with no editing taking place.

Also every Nikon above the midrange D200 has the ability to place a digitally signed key in the data of the image. Using a Nikon utility you can prove without a doubt that the image is in fact original.

Assuming the CSIs do their job properly there really should be no question at all as to the authenticity of the images.

There was a case recently in Australia because the Sydney police used MD5 Hashes to sign photos taken by speed cameras. Some guy did manage to get his ticket thrown out because early last year (late 2006?) a collision was detected and the MD5 algorithm was reverse engineered from that. But even this is reasonably difficult to do.

 

[Judge Sharpe]

Thanks guys- I think tha I have what I need. Just keeping everyone on the streight and narrow-LOL
Judge Sharpe

 

[PaulBennett]

...I have over the past years used film...how would one add to or subtract from a digital photograph...Is there a way to tell if a photograph has been "photoshopped" to use the popular vernacular?

First, it has nothing to do with taking the picture...film or digital...or the file type...tiff or jpeg, but it must be in the computer. PhotoShop & equivalent programs have numerous tools to alter content of an image. This alteration is detectable by examining details of the image under high magnification. Basically the 'grain' of the image is changed and that's what you look for.

The more competent the 'alter'er and the more time they took, the more difficult it is to detect changes. I've altered images many times such as removing power lines from landscapes, zits from faces, etc and the casual observer doesn't know where to look or what they are looking for so they accept the image.

You can no longer trust photographic evidence as proof of reality. Kind of like formatting a hard-drive...most of the time the original information is still there but most don't know how to find it. The detective must be smarter than the perp or be an ex-perp.