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Steganography III - Change only one Bit per Pixel

, 3 Apr 2004 CPOL
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An article about hiding each byte of a message bit-by-bit in eight pixels.

Sample Image - steganodotnet3.png


The application described in the last article Steganography II always added visible noise to the carrier bitmaps. This article is about splitting the bytes and hiding each bit in a different pixel. The hidden message is really invisible, because only the lowest bit of one color component is changed.


Before reading this, you should have read at least part one, Steganography - Hiding messages in the Noise of a Picture. This article uses the application described in part one and two, but you don't need the features added in part two to understand this one.

End of the rainbow

Replacing a whole byte of a RGB color produces a rainbow pattern. This is how a white image (all pixels just white) looks like after hiding a text message:

typical colour noise

On a colorful photo, these rainbow pixels may be alright. In grayscale mode, the same message in the same picture looks like this:

typical grayscale noise

As you can see, too many bits of the pixels have been changed. Now, we’re going to spread each byte over eight pixels and make the rainbow disappear.

Get and set bits

spreading a byte over eight pixels

For each byte of the message, we have to:

  1. Grab a pixel.
  2. Get the first bit of the message byte.
  3. Get one color component of the pixel.
  4. Get the first bit from the color component.
  5. If the color-bit is different from the message-bit, set/reset it.
  6. Do the same for the other seven bits.

The C#-functions for getting and setting single bits are simple:

private static bool GetBit(byte b, byte position){
	return ((b & (byte)(1 << position)) != 0);

private static byte SetBit(byte b, byte position, bool newBitValue){
	byte mask = (byte)(1 << position);
		return (byte)(b | mask);
		return (byte)(b & ~mask);

The rest of the code has not changed much. Hiding works like that now...

hide a message

...and extraction works like that:

extract a message

That's enough text for today. If you want to know the details, you should download the source.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Corinna John
Software Developer
Germany Germany
Corinna lives in Hannover/Germany (CeBIT City) and works as a Delphi developer, though her favorite language is C#.

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Comments and Discussions

GeneralImage hiding project Pin
M.Arulraj10-Dec-08 0:04
memberM.Arulraj10-Dec-08 0:04 
GeneralRe: Image hiding project Pin
Corinna John10-Dec-08 7:13
memberCorinna John10-Dec-08 7:13 
Generalimage hiding Pin
rame20-Nov-08 1:15
memberrame20-Nov-08 1:15 
GeneralRe: image hiding Pin
M.Arulraj10-Dec-08 0:41
memberM.Arulraj10-Dec-08 0:41 
     Hi friend I saw your msg. In my idea, you will follow LSB(Last significant bit) method.
     In this model,  each Original-image pixel bits are overwrite on the embedded-image's last bit of each pixels bytes.
     First you will get image pixels using Array. If you follow 
Java Applet, which have many methods. Java Swings is also very useful to it.
     In Java Vector concept is more efficient than the Array concept, Which is similar to the Array concept.
I am also doing this project. If you have any information please send to me.

.....see you next msg friend

my e-mail id

regards by
Laugh | :laugh:
GeneralRe: image hiding Pin
wwwwaaaalla7-Mar-10 6:46
memberwwwwaaaalla7-Mar-10 6:46 
QuestionCan anybody have the Base Paper for this Steganograhy -III Pin
pvprasad12-Apr-08 5:39
memberpvprasad12-Apr-08 5:39 
GeneralRe: Can anybody have the Base Paper for this Steganograhy -III Pin
Corinna John12-Apr-08 7:24
memberCorinna John12-Apr-08 7:24 
Generalimplementation USB Token Pin
Parneyan19-Jun-07 18:19
memberParneyan19-Jun-07 18:19 
GeneralSteganografy in java Pin
rafaelvecchio9-May-06 2:51
memberrafaelvecchio9-May-06 2:51 
GeneralRe: Steganografy in java Pin
Corinna John9-May-06 5:45
memberCorinna John9-May-06 5:45 

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