How to add two images and remove the added image

Hi

is it possible to add two image and did after some operation separate added image from it ?

Answer 1

[Image Analyst]

Yes.

[goldensona]

hi can you give me sample code how do to?

[Image Analyst]

I know it seems really obvious and trivial, but since you aren't giving any guidance at all, this is all I can suggest:

sumImage = image1+image2;
sumImage = sumImage / 2;  % Some arbitrary operation.
% Undue the operation, then subtract image2 to recover image1.
image1Recovered = sumImage * 2 - image2;

[Walter Roberson]

Note that if all you have at the time you want to separate the images is the added image, then separation is not generally possible. (It would be possible in some circumstances where additional information is known.)

[goldensona]

just i want to add image with another image in one file after that another m file i want to remove the added image (not in same file).

[Image Analyst]

If you don't have at least one of original images, you can't do it. For example, if I gave you the number 100 (let's pretend that is the gray level of an image pixel), can you tell me what two numbers I added together to give that 100? No, you can't. But if I tell you that one of the numbers was 42, then you can figure out the other number was 58.

[Walter Roberson]

Would this have to do with stegnograpy?

[goldensona]

one type of stegnography,but not with origninal image ,it water marking. i want to find the tampering in digital documents (binary image).

[Image Analyst]

It is a complicated and active field of research. You can find more in section 23.3 here: http://iris.usc.edu/Vision-Notes/bibliography/contentschar.html#OCR,%20Document%20Analysis%20and%20Character%20Recognition%20Systems

[goldensona]

we couldnt identify the modified region

[Image Analyst]

Then either your method of attack was very stealthy and effective, or your method of detecting attacks was unable to beat this method of attack. Do you have any further questions on the original question in this post? If not, go ahead and finish it by marking an accepted answer.

Answer 2

[Jan]

What does "adding" mean here? Do you want to add the pixel values, if so, does this mean averaging or a sum with ignoring the saturation? Or does adding mean a horizontal or vertically concatenation?

Then the meaning of "some operations" is important also: If you perform any destructive operations, you loose information and therefore a perfect reconstruction of the original data is impossible.

Therefore, in opposite to Image Analyst, I would answer:

 No, not in general.

[goldensona]

adding means ,combine two images ,i want to change one images and combine with another images show like one image, if i want the untouched image is it possible to retrieve after combining

Answer 3

[ram]

it is similar kind of tampering. am i right?

Answer 4

[ram]

if i cut the portion of one image and paste it in to another image and save as jpg. now i want to separate portion fromthe resultant image. is that possible?

[Walter Roberson]

Similar to what?

[Image Analyst]

It might be, depending on exactly what you did. A simple copy and paste would be detectable with normxcorr2() as long as you know what the pasted portion was - look for my demo on that in the Answers forum. But if you took just one or two pixels from an image and pasted it onto another one, then how do you know if it was pasted, or if the original image had those same pixels prior to pasting?