Embed new message to a image

Embed new message to a image

[matlabgeek]

I understanding is: We have a image, then we have matrix of it. Then we calculate the quantized DCT coeffcient. Then add something to this image, then we have a new quantized DCT coefficient? Am I correct of understanding above sentence. Any idea or sample code or reference link to do that?

[Walter Roberson]

http://uk.mathworks.com/matlabcentral/answers/?term=tag%3A%22steganography%22

[matlabgeek]

I went through these 152 posted questions, I did not find the suitable one for my questions? Could you provide me more information. Thanks

[Walter Roberson]

Try again. I went through and tagged more that were missing the tag. However, with there being over 500 questions about steganography, I got tired and gave up after about 100.

In particular see http://uk.mathworks.com/matlabcentral/answers/195666-i-need-a-code-for-hiding-a-text-in-an-image-using-dct-technique

Answer 1

[Image Analyst]

I'm not using DCT, but I attach some hiding demos for you. One to encode text and one to encode images.

See http://www.mathworks.com/matlabcentral/fileexchange/54155-encoding-text-into-image-gray-levels for the text demo.

P.S. We need to be careful about what code we share, and what language we use because the Mathworks is very cautious about hosting anything that can be considered encryption or steganography (I know from personal experience).

[Walter Roberson]

You can use dct2(), then do LSB watermarking on one or more of the coefficient arrays, and then idct2().

[matlabgeek]

Hi Image Analyst, For your hide_text_in_image.m, when you insert hidden string into image, how do you check if you insert successfully since we cannot see the inserted string using our eyes

[matlabgeek]

Hi Walter,

Do you have sample code to do that? Thanks

[Walter Roberson]

Insertion is always successful if the array is changed. Whether the insertion is in the right place is a different matter.

[Image Analyst]

If you run my demos, you see I first hide stuff, then you observe that you cannot see the hidden stuff, then I recall it and get the exact stuff that I hid, so that's how I check that I hid it successfully.

[matlabgeek]

Hi Image Analst, "If you run my demos, you see I first hide stuff, then you observe that you cannot see the hidden stuff, then I recall it and get the exact stuff that I hid, so that's how I check that I hid it successfully."

You have two files: hide_text_in_image.m and LSB_Watermarking.m. Which file do you refer to in your sentences. Thanks

[matlabgeek]

Hi Image Analyst and Walter,

Could you help fix this problem: http://www.mathworks.com/matlabcentral/answers/217004-need-help-on-my-dct-and-quantization-code-for-image-compression

[Image Analyst]

Both of them. Both demos first hide, then recover.

For that other person's question in your link, I doubt it's still a problem for them after 7 months of no activity. Anyway, I don't research compression methods. It's not worth my time when I can just use built in compression methods, like imwrite(), that other people have already written and perfected.