Watermark embedding method and apparatus, and system

A watermark embedding apparatus, comprising:

• a processor configured to:
• receive a current input image;
• select a watermark pattern to be embedded in the current input image;
• generate a watermark image based on the watermark pattern;
• generate an alpha blended stego image by alpha blending the current input image and the watermark image;
• and
• provide the alpha blended stego image,
• wherein the processor generates the watermark image by calculating at least one of allowable minimum and maximum alpha value α and allowable minimum and maximum pixel value of the watermark pattern applied to a first pixel of the original image,
• wherein the at least one of allowable minimum and maximum alpha value α and allowable minimum and maximum pixel value are determined by a difference d of pixel value of the first pixel by between the original image and the alpha blended stego image by embedding the watermark pattern to the first pixel,
• wherein the first alpha blending rule is generated based on statistical values by analyzing all of cases where the watermark pattern has pixel values of a minimum pixel value to a maximum pixel value with respect to a pixel value of the watermark pattern for all pixel value applicable to the first pixel of the original image when the difference d is defined as an invariable value, and
• wherein the watermark image is generated by determining the pixel value of the watermark pattern and an alpha value α,
• wherein the pixel value of the watermark pattern and the alpha value α are determined based on the at least one of allowable minimum and maximum alpha value α and allowable minimum and maximum pixel value of the watermark pattern, and
• wherein the allowable minimum and maximum pixel value of the watermark pattern is calculated based on the watermark pattern without using pixel values of pixels in the original image.