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Digital Image Processing Systems
Published in Scott E. Umbaugh, Digital Image Processing and Analysis, 2017
The newest standard for video signals is ultrahigh definition (UHD). The UHD standard uses an aspect ratio of 16:9, the same aspect ratio as HDTV. However, the UHD standard specifies a higher resolution than HDTV. The UHD standards currently defined include 2160p or 4K, which is a progressive scan of 3840 columns by 2160 rows, and 4320p or 8K, a progressive scan of 7680 pixels columns by 4320 rows. Although very few television stations are broadcasting UHD, the 2160p level of resolution is supported by new Blu-ray video players and the 4320p is equivalent to images shown at commercial movie theaters. For most in home television viewing, consumers will not be able to discern the difference between HD and UHD, due to the typical distance that people use for watching television—the extra resolution is only noticeable up very close to the screen.
Fundamentals of Digital Video Coding
Published in Yun-Qing Shi, Huifang Sun, Image and Video Compression for Multimedia Engineering, 2019
Ultra HD: 4K UHD is a resolution of 3840 pixels × 2160 lines (8.3 megapixels, aspect ratio 16:9) and is one of the two resolutions of ultra-high-definition television (UHDTV) targeted towards consumer television, the other being 8K UHD, which is 7680 pixels × 4320 lines (33.2 megapixels). 4K UHD has twice the horizontal and vertical resolution of the 1080p HDTV format, with four times as many pixels overall. Likewise, 4K UHD has three times the horizontal and vertical resolution of the 720p format, with nine times as many pixels overall (ITU 2012).
Multimedia Systems
Published in Sreeparna Banerjee, Elements of Multimedia, 2019
Ultra-high definition (UHD) has very high resolutions and has two categories: 8K UHD has a resolution of 7680 × 4320, or 33.2 MP; 4K UHD has a resolution of 3840 × 2160 for HD and 4096 × 2160 for a digital camera.
A metal oxide TFT gate driver with a single negative power source employing a boosting module
Published in Journal of Information Display, 2020
Yan-Gang Xu, Jun-Wei Chen, Wen-Xing Xu, Lei Zhou, Wei-Jing Wu, Jian-Hua Zou, Miao Xu, Lei Wang, Jun-Biao Peng
Figure 10 shows the output waveforms of the 1st and 15th stages with the same load values as in Figure 9 at a 66.7 kHz clock frequency. The measured pulse width was 3.2 μs. It was found that the swing of the output voltage is still close to the power source range. Furthermore, the output waveforms at a higher frequency are as good as those at a low frequency. This means that the proposed gate driver may be suitable for application in high-resolution displays. Take UHD (3840(RGB)*2160) for example; it takes only about 3.8 μs to drive each row line at a 120 Hz frame rate.
A novel LTPO AMOLED pixel circuit and driving scheme for variable refresh rate
Published in Journal of Information Display, 2023
Jung Chul Kim, I. Sak Lee, Hyung Tae Kim, Jong Bin An, Jae Sung Kim, Juhn Suk Yoo, Han Wook Hwang, Hyun Chul Choi, Yong Min Ha, Hyun Jae Kim
Figure 7(a) shows the input signal waveform of the S1 gate driver as tCOMP is varied from 2.0 µs to 8.0 µs. Figure 7(b) to (d) show the simulation results when D-TFT VG (N2) and VS (N1) change at tCOMP value of 2.0 µs, 4.0 µs, and 8.0 µs, respectively. At this time, tPROG is fixed at 2.0 µs. In a conventional driving scheme, tPROG and tCOMP are identical; the tCOMP values of FHD and ultra-high-definition (UHD) at 120 Hz frame rate are 8.0 µs and 2.0 µs, respectively. When tCOMP is 2.0 µs and 4.0 µs, the VGS values of the D-TFT are −4.10 V and −3.69 V after D-TFT VTH sensing, as shown in Figure 7(b) to (c), respectively. When tCOMP is 8.0 µs, the D-TFT VGS is −3.28 V, as shown in Figure 7(d). As the simulated D-TFT VGS is −3.18 V, with longer tCOMP, the D-TFT VGS becomes more similar to VTH. As tCOMP becomes longer, VGS converges to the D-TFT VTH. From these simulation results, the longer tCOMP allows more precise sensing of D-TFT VTH variations. Figure 8 shows the relative IOLED error rates versus the D-TFT VTH variations of −3.0 V ± 0.1 V ∼ ± 0.5 V at 5 gray (0.2 nits) corresponding with different tCOMP. The relative IOLED error rate ranges from −28.6% to 26.4%, −16.2% to 15.6%, and −6.2% to 6.6% for tCOMP of 2.0, 4.0, and 8.0 µs, respectively, confirming that the proposed pixel circuit with the longest tCOMP of 8.0 µs indeed compensates more effectively for the D-TFT VTH variations. Also, the pixel circuit can freely extend tCOMP owing to its overlapping compensation scheme. The luminance uniformity of the manufactured 6.0-inch LTPO-based AMOLED display was measured to evaluate the compensation performance of the pixel circuit with various tCOMP values. Figure 9(a) to (c) present the optical images when tCOMP was 2.0, 4.0, and 8.0 µs, respectively. As tCOMP increases, the luminance uniformity improves. An ultra-high-resolution camera (RADIANT SOLUTION FPiSTM) was used to quantify uniformity. The measured luminance was 0.2 nits at 5,000 points within the panel. As a result of measuring local luminance uniformity, the standard deviations of luminance became smaller as tCOMP became longer (0.056, 0.024, and 0.008 for tCOMP values of 2.0, 4.0, and 8.0 µs, respectively), as shown in Figure 9(d) to (f). These results confirm that the simulation results provide accuracy for the measurement results of luminance uniformity. Since the proposed pixel circuit can increase the tCOMP, even if tPROG (or tSCAN) is short as the frame rate increases, the compensation performance can secure the same level as the FHD panel because the tCOMP of FHD is 8.0 µs. Therefore, the proposed pixel circuit ensures excellent luminance uniformity even at 120 Hz QHD high-frame rate driving. Also, as the pixel circuit can be driven at 120 Hz, the moving image quality of the AMOLED display can be improved [27–29].