![screen marker screen marker](https://i.ytimg.com/vi/mK-Bm7Dxv8c/maxresdefault.jpg)
In addition, we establish that our system is robust against rotation. Through four evaluations, we confirm that the pointing error is within 1 mm, and that the proposed system works, when the distance between the screen and smartphone is 4-24 times the size of the AR marker. We mainly focus on applications, such as digital signage, where users point their smartphones at the display content. To address this problem, we propose an easy-to-install localization method that uses an array of AR markers, which are made imperceptible to the human eye through chromaticity vibration at 30 Hz. Although some studies have addressed this issue, few have focused on near-screen interaction without additional hardware. However, these visible markers interfere with the display content this problem is critical for localization over a wide range of interactions, and fewer markers result in less reliability and accuracy. Communication through QR code-like markers and localization via AR markers are common examples of such interactions. Owing to the pervasive use of displays and smartphones, mobile interactions with display screens have gained attention within the advertising and gaming industries as well as in human-computer interaction research. We can express color switching as a wave c d (t) with the color value varying in time as follows: Moreover, by showing that we can do marker extraction in three frames, we also show that constant marker extraction is possible. In theory, given the display refresh rate of 60 fps and the capturing rate of 45 fps, the marker can always be distinguished from the content with only three sequentially captured images. In addition, the marker mask becomes more apparent over time by accumulating the differences between areas outside of the mask, and areas within the mask. As such, we can determine the marker mask by aggregating the locations where R 1 R 2 R 3, thereby recovering the marker. R 1 R 2 R 3 within the mask, whereas outside the mask, R 1 = R 2 = R 3. Moreover, there will be a particular order for these three values, say R 1, R 2, R 3, R 1, R 2, R 3, In other words, if we focus on a single pixel value in the frame, we can expect it to be one of three values R 1, R 2, and R 3. Thus, we can expect a pattern from three sequentially captured frames. For our method, we set f d = 60 Hz and f c = 45 Hz resulting to f b = 15 Hz. Marker recovery will rely on this pattern so we want to choose f d and f c that results to a small number of frames. Each beat will have f c / f b frames that repeatingly follow a particular pattern. Given that the refresh rate f d and the capture rate f c have a small difference, then we can calculate a beat frequency f b = | f d − f c |.
![screen marker screen marker](https://cdn.shopify.com/s/files/1/2295/6445/products/TS082-store_1000x1000.jpg)
We rely on the beat phenomenon for extracting the embedded marker. Figure 4 shows the relationship between the timing of switching on a screen and the timing of capturing on a camera. each of the image pair appears at 30 fps.
#Screen marker update
Temporal relationship between update rates of display and camera. The results show 1) selecting complementary colors in the a*b* color plane maximizes imperceptibility, 2) our method is extremely robust when used with static contents and can handle animated contents up to certain optical flow levels, and 3) our method was proved to work well in case of small movements, but large movements can lead to loss of tracking. In this paper, we have conducted three experiments. Our marker detection process does not require mobile devices to be synchronized with the display, while certain constraints for the relation between camera and display update rate need to be fulfilled. To embed markers, similar to previous work, we display complementary colors in alternating frames, which are selected by considering L*a*b color space in order to make the markers harder for humans to detect. Our method consists of two parts: marker embedding on external displays and marker detection. We present a novel method to enable users to experience mobile interaction with digital content on external displays by embedding markers imperceptibly on the screen.