In Matlab environment, do you export the output of the Inverse DCT from double to uint8 (to write an image file jpg, png, bmp etc) then reading the resulted image and converted it into double again to extract the hidden message?
The issue is that, the output of the last stage of DCT Steganography isFloating-point numbers and not Integer numbers (0-255). The message can not be recovered when the Stego-Image exported outside Matlab then reused inside Matlab to extract the message.
My process for hiding is:
DCT --> Quantization --> Embedding the message -->> Dequantization -->Inverse DCT --> Stego-Image (my question)
For extracting the message:
Stego-Image --> DCT --> Quantization --> Extracting the message
Aparna Sathya Murthy I am hiding the text message in all RGB channels of the image. I am using the following to convert between uint8 and double https://www.mathworks.com/help/releases/R2020a/symbolic/double.html
https://www.mathworks.com/help/releases/R2020a/fixedpoint/ref/uint8.html
The issue is, when I convert the output of the inverse DCT from double to uint8 so I can write an image as a file, then using this file again in Matlab and convert it back to double from uint8, the hidden message can not be recovered.
Note: that the output of the inverse DCT stage is float-point numbers when the message is added.
Aparna Sathya Murthy No, my message is not floating point. OK, just let me clean my code and I will send to you. Thank you for your help.
An image can be saved as double too, only when it needs to be displayed it has to be converted to uint8
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