IMAGE COPYRIGHT IMAGE COPYRIGHT PROTECTION USING PROTECTION USING WATERMARKING IN WATERMARKING IN WEB APPLICATION WEB APPLICATION WITH GDI+WITH GDI+

Soetam Rizky Wicaksono, S.Kom, MCP

Information System Faculty Information System Faculty STIKOM Surabaya STIKOM Surabaya Raya Kedung Baruk 98Raya Kedung Baruk 98SurabayaSurabaya

Why Need Protection ?

• Too many images in web• Duplication, copyright fraud,

retouching / manipulation• Protection via login process or

subscription is not the best way anymore, too many ways to crack them, event with kiddies script

Solution Options For Web

• Image serialization( already done at SITIA 2006 )

• Convert into machine unreadable format although human readable such as : base-64, HTML etc.( Will be done at SNIKTI 2007 )

• Steganography( Will be done at KNSI 2007 )

• Watermarking

Chosen Option

On-the-fly watermarking :• Can be used not only in web

application, however, more appropriate applied in web application

• Using GDI+ in .NET Framework, thus it won’t charge additional time for webmaster in creating watermarking in upload process

Why Watermarking ?

• The amount of embedded information has a direct influence on watermark robustness.

• Embedding strength – there is trade-off between watermark embedding robustness and quality.

Sagarmay, Deb (ed), “Multimedia System and Content-Based Image Retrieval”, Idea Group, London, 2004.

Watermarking Weaknesses

• Selecting layers with the same pattern or same color

• Eliminate using imaging tools • Cropping technique

Avoid Watermarking Attacks

• Avoid placing watermark layer only in the corner of original image to eliminate cropping attack

• Placing more than one watermark layer

• Make gradient in watermark layer to avoid same-pattern attack

GDI+• An all-purpose drawing model for .NET

applications. • GDI+ has a number of uses in .NET, including

writing documents to the printer, displaying graphics in a Windows application, and rendering graphics in a web page.

• Using GDI+ code to draw a graphic is slower than using a static image file.

• However, it gives much more freedom and enables several possibilities that weren’t possible (or were prohibitively difficult) in earlier web development platforms

GDI+ Basics

• Create the in-memory bitmap where to perform all drawing.

• Create a GDI+ graphics context for the image. This gives the System.Drawing.Graphics object

• Perform the drawing using the methods of the Graphics object. Draw and fill lines and shapes, and can even copy bitmap content from existing files.

• Write the binary data for the image to the browser by using the Response.OutputStream property.

Watermarking Implementation

• Assuming that image file which will be protected already located at web server, GDI+ will read the original image as new layer

• Generate a new layer for watermark, which consist of copyright text

• Merge both layers

Detail Implementation• Take place at zero pixel for x

coordinate from the original image and started from 40 pixel for y coordinate from the original image.

• Assuming that image file which will be protected from internet infringement copyright has size more than 100x100 pixels.

• Only aim to be example, in further development, it should be adjusted within the image size.

Detail Implementation

Original image

Watermark layer

40

ASP .NET 2.0 Implementation

• Create original image as the container for watermarking layer

• Create a new layer which will going to be a watermark layer, contains text with gradient brush in order to restraint layer-removing technique

ASP .NET 2.0 Implementation

• Merging both layer into one layer and save it into a memory stream, and then display it into JPEG format.

• Assuming that the original file is also in JPEG format.

• For real application, result format should be the same with the original format of image file.

Future Development

• Watermark layer should contain many constraint to restrict it from advanced layer removing tehcniques, and as well printing infringement abuse.

• Reserve another method to combine, in order to increase security in image layering

Future Development ( II )

• Text variable in watermarking layer should be in better format, such as copyright author, date and also can include EXIF information.

• Integrate it into an XML Web Service

• Watermark layer can be encrypted using ligthweight algorithm such as TEA or XTEA

www.soetamrizky.netsoetam@stikom.edu

Soetam Rizky WicaksonoSoetam Rizky Wicaksono

Information System Faculty Information System Faculty STIKOM Surabaya STIKOM Surabaya Raya Kedung Baruk 98Raya Kedung Baruk 98SurabayaSurabaya