Image talk:StenographyOriginal.png

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How was this image made? 70.68.203.120 07:02, 26 February 2007 (UTC)

What is hidden in this picture and how can I extract it? -- Taku 01:12, Nov 11, 2004 (UTC)
Is there an original picture so I can compare the two? -- Taku 17:13, Nov 16, 2004 (UTC)

The article on steganography explains how to extract the data, which is this image: Image:StenographyRecovered.png. I followed the instructions and got the hidden image. --Elijah 23:36, 2005 Jan 3 (UTC)

Could someone give an example of "appropriate software"? --Amy

OK. This is what I did:
1. Save the file in *.RAW format with header size 0 (default). You can use Photoshop for this.
2. Take a Hex Editor (e.g. Hex Workshop), and do a & (AND) operation on the file (per 8-bit) with the number 3.
3. Save the file.
4. Open it with Photoshop again (with the same *.RAW settings you saved it with).
5. In Photoshop's menu -> Image -> Adjustments -> Auto Levels (Or you can go to Image -> Adjustments -> Levels... and make it even brighter). -- Wolf359 01:38, Jul 06, 2005 (ISRTC)


How do I do step 2? Klosterdev 18:22, 29 May 2007 (UTC)


Some programs have Image Arithmetic functions that can perform arithmetic on the colour values in an image, which is easier if you don't know what a hex editor is. In Paint Shop Pro:
1. Open the StenographyOriginal.png file.
2. Create a new image with 24-bit colour depth (16 million colours), any size. Fill it with colour #030303 (this looks like black).
3. Go to the menu Image > Arithmetic... Select Image#1: StenographyOriginal.png, Image#2: the 030303 black image, Function: AND, Channel: All channels. Click OK.
4. Create a new 24-bit image and fill it with colour #858585 (looks like gray).
5. Go to the menu Image > Arithmetic... Select Image#1: the 030303 black image, Image#2: the 858585 gray image, Function: Multiply, Channel: All channels. Click OK.
(The reason for steps 4&5 above is that in Paint Shop, increasing brightness just adds to the overall brightness, instead of increasing it proportionally. Using Adjust > Brightness/Contrast leads to a gray box.)
6. Mira! Kittycat! ^_^ --megabigblur

Umh, for steps 4&5 you want to use #555555, not #858585. hex 55 == dec 85. And if you increase Contrast instead of Brightness, it will work with Paint Shop. Per definition, "brightness" modifies by adding/subtracting a constant value, while "contrast" correctly scales the image by a given factor.
For Paint Shop Pro X follow the first three steps above to create the combined image (make sure "Divisor" is set to 1 and "Bias" to 0), then in the menu go to Adjust > Color > Fade Correction to obtain the final image. Unfortunately I don't know what processes are involved here. - Diceman 16:43, 20 January 2006 (UTC)

Actually you can do the same and much more in Photoshop if you have the Filter Factory plugin. For instructions see My Talk Page --Ukdragon37 18:18, 14 October 2005 (UTC)

How do I do this in Paintshop Pro 6?

Never MIND! Dumb QUESTION! That I ASKED!

[edit] PhotoPaint Method

  1. Open image
  2. Set paint color to RGB 3,3,3
  3. Select paintbrush tool
  4. Select "Logical AND" in property bar
  5. Paint over entire image (sets pixel RGB components to the range [0-2])
  6. Select Image / Auto Equalize option (sets pixel RGB components to the range [0,85,170])

sgb 18:54, 7 December 2005 (UTC)

[edit] GIMP

How can this be done in GIMP? --Fibonacci 00:30, 22 November 2006 (UTC)

This gets close (you can vaguely see the cat, but there are bits of tree in there too):

  1. Duplicate the layer
  2. Posterise the upper layer to 64 levels
  3. Set the upper layer's mode to Subtract (it should go black)
  4. Flatten Image
  5. Multiply (e.g. use Brightness-Contrast and set both to maximum)

I suspect the Posterise step is rounding to the nearest rather than taking the floor. Maybe adding first will help?

[edit] ImageMagick command line

If you have ImageMagick installed, you can use the following command:

convert StenographyOriginal.png -fx 'p&#030303' -fx '85p' StenographyRecovered.png

This uses ImageMagick's Fx Special Effects mathematical function system. It's really neat.

SWalkerTTU 23:13, 13 January 2007 (UTC)

That didn't work for me, but this does:
convert StenographyOriginal.png -fx '((u*255)&3)/3' StenographyRecovered.png
And, this hides image 2 in image 1, although it unfortunately doesn't dither image 2 (not sure what command to use for that):
convert img1.jpg img2.jpg -fx '((u*255)&252)/255+v/85' test.png Κσυπ Cyp   20:05, 22 July 2007 (UTC)
I think I originally used Corel Photopaint to do it. (I hadn't heard of imagemagick at the time, and hadn't even switched to Linux...) Κσυπ Cyp   20:05, 22 July 2007 (UTC)