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syvaidya / openstego

OpenStego is a steganography application that provides two functionalities: a) Data Hiding: It can hide any data within an image file. b) Watermarking: Watermarking image files with an invisible signature. It can be used to detect unauthorized file copying.
https://www.openstego.com
GNU General Public License v2.0
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Watermarking breaks JPG images (horizontal color bands) #23

Open alentsch opened 6 years ago

alentsch commented 6 years ago

Hello!

I am trying to watermark my photos with openstego v0.7.2 under the Linux command-line. However about 80-90% of the JPG images show light to strong distortions such as horizontal color bands. Here is an example:

After watermarking: https://www.flickr.com/photos/turbopunsch/40801625282/in/photostream/ https://c1.staticflickr.com/5/4777/40801625282_a9b662bfab_b.jpg

Before: https://www.flickr.com/photos/turbopunsch/40801624302/in/photostream/ https://c1.staticflickr.com/5/4782/40801624302_8d704b0168_b.jpg

Only about 10% of my images are OK and have 100% signature strength. The other images show either visible image distortions or the signature strength is anywhere between 0% and 100%. I tried different images sizes and JPG compression ratios, but can not see any difference. Am I doing something wrong?

PS: I tried to increase the maximum memory allocation for Java with the option -Xmx2048m, but that does not make any difference.

syvaidya commented 6 years ago

@alentsch I tried the JPG, but I am not seeing any bands in the embedded image. The embedding strength is also 100%. I guess that Flickr would be doing some changes to the JPG and so I am not able to reproduce the issue. Would it be possible to attach the original images here?

alentsch commented 6 years ago

@syvaidya thank you your reply. I attached both images now to this message - sorry I didn't know that attaching files was possible - much easier of course. When I check the watermark with the command $ java -Xmx1024m -jar /usr/share/openstego/lib/openstego.jar checkmark --sigfile=xxx.sig --stegofile=xxx.jpg I get a strength of 0.5 (50%) for the attached image. Where the image "turns into blue" (not in the original) there are also some boxes, which are not in the original image.

Thank you very much for your help again!

Image with watermark: 40801625282_a9b662bfab_b

Originial image: 40801624302_8d704b0168_b

Eyremba commented 5 years ago

Was this fixed now? Or does OpenStego still have this problem?