Abstract
A pictorial image is automatically generated from natural image by the strokes of an imaginary brush. We intentionally select a stroke's direction among the discrete angles of 0, 45, 90, and 135 degrees according to each bit pattern of the embedded data, and the brush's color is computed by averaging the colors in the drawing area. Next, we divide the pictorial image into N x M blocks, where each block can store 2 bits, and add positive noise of blue color to the border and negative noise to the internal region of the stroke. The border can be efficiently detected in the blue color space, and the data are extracted by detecting the edges of the strokes using Laplacian of Gaussian filter, zero crossing, and Hough transform. We take an image with a digital camera by change its resolution. We successfully embedded and extracted 150 bytes of data in a 100 x 148 mm image. However, our method requires high-resolution images for extracting data in high accuracy.
