Σχετικά με το true και false 4K, ήταν πάντα ένα θέμα γενικού ενδιαφέροντος για τους κατασκευαστές και τους χρήστες. Το 4K αναφέρεται σε ανάλυση 3840x2160 ή 4096x2160. Ένα σήμα του οποίου το πλάτος δεν μπορεί να φτάσει τα 3840 δεν μπορεί να ονομάζεται 4K και ένα σήμα του οποίου το ύψος δεν μπορεί να φτάσει τα 2160 δεν μπορεί να ονομάζεται 4K. Το ίδιο σήμα 4K έχει επίσης διαφορετικές διαφορές, όπως αν ο ρυθμός καρέ είναι 30Hz ή 60Hz, αν ο χρωματικός χώρος είναι YUV ή RGB κ.λπ. Για συσκευές οθόνης με πολύ καλά εφέ οθόνης, η διαφορά στην ποιότητα της εικόνας είναι πολύ εμφανής.
Ρυθμός καρέ: 30Hz ή 60Hz
The maximum frame rate of HDMI 1.4 standard is 30Hz, that is, 30 frames of images are transmitted per second, while the maximum frame rate of HDMI 2.0 is 60Hz, that is, 60 frames of images transmitted per second. The parameters of 60 frames are twice as high as that of 30 frames, and the picture quality and details are better. The higher the number of frames, the smoother the picture, and the intuitive experience can best be reflected. The higher the value, the closer the picture is to the real world observed by the human eye.
The difficulty of 4K 60Hz processing lies in the large amount of data and high bandwidth. The point frequency of ordinary 1920x1080 60Hz is 148MHz, while the point frequency of 4K 60Hz is 594MHz, which requires high signal transmission and processing.
Χρωματικός χώρος 4:4:4 ή 4:2:2
In recent contacts with signal processing manufacturers, many manufacturers have begun to emphasize that their color space is 4:4:4. What is this? In fact, for 4K, the color space is also a very important parameter. The most widely used formats are RGB and YUV, both of which are a color coding method YUV. YUV and RGB can be converted to each other. Like RGB, which represents red, green and blue, the three letters of YUV represent the luminance signal and U, V color difference signals respectively.
Here, let's talk about YUV first, 4:4:4, which represents the three signal sampling storage methods of YUV. In addition to 4:4:4, there are also 4:2:2, 4:2:0, 4:1: 1 Three sampling formats. In simple terms, the 4:4:4 signal is lossless, the information is more abundant, and the picture color is better, but the requirements for storage space and transmission bandwidth are very high. The other three methods compress colors in order to save bandwidth and storage space. What we said before about 4K is mostly 4:2:2.
Compared with RGB, the compression method of YUV has inherent advantages. It can separate the information of outline and color, and only compress the color without affecting the outline. As shown in the figure above, the Y signal is Luma, which represents the brightness information, which is the outline intuitively. Whether it is 4:2:2 or 4:2:0 or 4:1:1, the brightness Y corresponds to 4, which means that the contour information will not be compressed, and the compression will compress the color information. Figure Chronma represents the U and V signals. The RGB compressed three-primary signal is more likely to affect the sharpness of the outline. YUV compression color is really a cost-effective compression method, but with the continuous development of technology and the improvement of audience demands, YUV4:4:4 has also begun to increase.
Summary: Due to different parameter standards, we now have a true and false 4K battle. Now, 4K display that reaches 60Hz 4:4:4 is generally called true 4K. With the continuous development of demand in the audio-visual field, at present, there are more and more display devices and signal processing devices that can meet this standard.
