Kharittha Thongkor

Learn More
Problem of fake image in ID card spreads all over the world e.g. false Thai national ID card in Thailand. This problem is quite difficult to detect because appearances of human face always change. Digital image watermarking for photo authentication in Thai national ID card is therefore proposed in this paper to overcome such a problem. Basically, a(More)
This paper considers a situation where the copyright of distributed images/photos in social networks is violated. Since the images/photos published on social networks are usually modified and/or compressed to the match the template provided by the service providers, we thus propose a digital image watermarking based on DWT coefficients modification to be(More)
In this paper, we consider the digital watermarking based on the modulation of image pixels in YCbCr color space, and propose a method to improve its performance. Basically, we divide the watermark into two parts, and embed each part into each chrominance channel. Based on this concept, in the watermark extraction process, we can reduce the number of the(More)
This paper addresses the difficulty of detecting and/or verifying a watermark signal from watermarked image contained in unauthorized printing media. We consider a situation where an image owner tries to detect his/her embedded watermark from a photo having unauthorized image inside. This taken photo normally contains distortions such as those from the(More)
In this paper, we propose a method to improve the performance of the digital watermarking based on the modulation of image pixels in YCbCr color space. Basically, we divide the watermark into two parts, and embed each part into each chrominance channel; Cb and Cr. As a result, in the watermark extraction process, the number of the watermarked pixels used in(More)
This paper presents a spatial domain image watermarking method based on regularized filter. In the proposed method, a watermark image is embedded into a host color image directly by modifying the blue color component. The watermarkmark strength is controlled by two factors, i.e. a constant value and the luminance within a local embedding area. The(More)
Problem of altering content of faxed document extends in wider range including in Thailand. Since most companies/organizations in Thailand use only one fax machine for common use in each department to reduce the telephone payment and complexity of fax management, someone with malicious intention may get a faxed document directly and personally from fax(More)
This paper proposes a digital image watermarking method in homomorphic domain. In the proposed method, a homomorphic filter is applied to the host color image to extract a low variational illumination component. This component is used to embed a binary watermark image with the same size as host image. The watermark extraction is achieved by using an(More)
This paper presents an image watermarking method where partial embedding approach is implemented in order to avoid interference from other nearby watermark bits. With cautious selection of watermark embedding positions, the maximum number of embedding bits can also be achieved. Precisely, the embedding positions are pseudo-randomly selected from the blue(More)