Kharittha Thongkor

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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)
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 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)
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 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)
This paper addresses a problem of detecting watermark signal from watermarked printed image behind a glassy object. By considering a situation where an image owner tries to extract his/her embedded watermark from a camera-captured image having unauthorized image inside, such image will always include RST (rotation, scaling, and translation) and perspective(More)
This paper addresses the difficulty of extracting and/or verifying a watermark signal from watermarked image contained within poster. We consider a situation where an image owner tries to extract his/her embedded watermark from a camera-captured image having unauthorized image inside. This image normally contains rotation, scaling, and translation and(More)