The authors have already proposed introducing “film mode” signal processing into EDTV-II. In the mode, I-P (interlaced to progressive) scan conversion of film images can be theoretically improved without a VT helper signal by using a reserved bit of the EDTV-II signaling codes as a film mode signaling code. In this paper, they propose an improved signaling method which can be applied to various frame rates of original films by indicating whether the current field has been generated from the same film frame as the previous field. They also implemented a signaling code regenerator and a film mode I-P scan converter, and clarified picture quality by using subjective assessments. The assessments showed that the picture quality decoded in the film mode was generally better than the one in the current EDTV-II mode.
In boundary detection of color images, it is essential to form local edge elements that are detected by a local edge detection method into groups for finding straight or curved lines. A new boundary detection method based on the Hopfield neural network is proposed. First, an image is divided into blocks. In each block, two edge segments at the most are detected. Then, a unit of the network is assigned to each edge segment. Some properties of edge segments belonging to a boundary are embedded in an objective function of the network, and the boundary is detected by minimizing the function. Experimental results show that the method is applicable for partially disconnected and/or blurred boundaries.
This paper investigates the characteristics of a circularly polarized Yagi-Uda array. A one-point-fed circular wire loop with one open point is used as the driven element to launch circular polarization. Loops or crossed wires are used as parasitic elements. Standing wave current exists on one part of the driven loop and traveling wave current exists on the other. We found that circular polarization is produced by the rotation of these currents as a function of time. The design charts for the circumference of a 3-element Yagi-Uda loop array are calculated to obtain desired values for the axial ratio, the directional gain and the input impedance. The circumferences of the array are chosen from these charts. The array's characteristics are measured and then compared with the calculated results, which include the effects of a feed cable. An axial ratio of less than 0.1 dB and a directional gain of 9.6 dB are obtained for a 10-element Yagi-Uda loop array.