LCD color technical indicators
Color, a topic that has to be said, the recent discussion on the color of LCD monitors seems to be intensifying, from 16.2M, 16.7M, to 8bit, 6bit, these professional terms sound not only lack of relevance, but also easy to lead Misty water. This article will analyze the difference in color of the LCD monitor from a technical point of view, and finally implement it in practical applications, so that you can be aware of when buying LCD.
What is true color display? From the perspective of color, both CRT and LCD have the concept of true color display, which means that the three color channels of RGB (red, green and blue) have physical display of 256 levels Gray scale ability. All CRT monitors have true color display capabilities, while LCD monitors are not the same. The LCD panel that can physically display a true color display, we call it a true color panel-that is, it has the ability to physically display 16,777,216 colors.
A driver IC used as a liquid crystal display
How are 8bit panel and 6bit panel defined?
For the color display capability of the LCD panel, we usually use it for each color channel. The LCD panel can display the number of gray levels to describe. If 256 (2 to the 8th power = 256) gray scale can be displayed on each color channel, we call it 8bit panel, which is also a true color panel; if only 64 (2 of 2) can be displayed on each channel 6th power = 64) gray scale, then we call it 6bit panel, which is also a pseudo-color panel. At present, mainstream desktop LCD products use 6-bit and 8-bit panels, and there are many products that use 6-bit panels in low-end products.
The subtle relationship between response time and color The number of digits of the LCD panel can be understood from the perspective of the maximum driving number of the LCD driver IC. For example, the maximum driving number of the 6bit panel can only be 64, which cannot achieve true color display. Hardware requirements. However, there are also advantages in a small number of driving channels. For example, it can reduce the duty cycle, thereby reducing the design difficulty in terms of viewing angle and contrast. From the physical structure of the liquid crystal panel, the 6bit panel, that is, the liquid crystal molecules have only 64 kinds of controllable states between pure black and pure white. Such few states are naturally easy to control, which is why most of the 12ms, An 8-ms LCD is generally a 6-bit panel.
The color of the 6bit panel is less than 2% of the 8bit panel
The 6bit panel can only display 262144 colors (64 × 64 × 64 = 262144), while the 8bit panel can display 16777216 colors (256 × 256 × 256 = 16777216). Physically, the 6bit panel can display less than 2% of the color of the 8bit panel.
However, in actual use, the display of the two panels with a tens of times difference in color number is almost the same in the eyes of most users. Because from the user's point of view, many pictures look colorful. In fact, the number of colors used in a picture or a video is not very large. It is likely that there are only tens of thousands or hundreds of thousands of colors, and 16.77 million colors are almost not. It may appear on a certain screen at the same time.
And the perception of color is greatly affected by the user's use environment and the user's sensitivity to color. For ordinary users who have not received certain professional training, the difference between displaying 260,000 colors and displaying 16.77 million colors is not much different. .
The color enhancement technology for "extending the life" of 6bit panels Although 6bit panels cannot be compared with 8bit panels, it is not appropriate from an economic point of view to switch to 8bit panels all at once. Faced with the increasing demands of users, major LCD manufacturers have launched their own exclusive color enhancement technology for 6-bit panels.
The main purpose of this type of LCD color enhancement technology is to narrow the gap between 6bit and 8bit panels and extend the application life of 6bit panels. From the perspective of implementation technology, it mainly uses PD (Pixel Dithering, pixel dithering) algorithm or FRC (Frame Rate Control, frame rate control) technology. These two technologies are easy to understand from the perspective of color science.
Using visual inertia and for animation, FRC technology mainly utilizes the physiological characteristics of a person, such as visual inertia. This characteristic roughly means that the brightness feeling of the human eye does not disappear immediately as the brightness of the object disappears. The following picture is a good example of visual inertia. There is no black dot in the picture, but our eyes can "see" many black dots.
This picture is a method that uses the visual inertia of the naked eye to let us see and make the 6bit panel display more color, and the same is true.
FRC technology is consistent with the principle shown in the above figure, we can also make an analogy to help readers understand. You can try to adjust the computer screen (preferably a CRT monitor) to full-screen pure red, and then switch to full-screen pure yellow. The moment we just switched, what we "see" on the screen is not red or yellow, but orange. The reason is that the initial red color stays in our eyes because of visual inertia, and the newly-entered yellow light and the temporary red light feel superimposed, and we "see" orange, a type that did not exist. colour. The 6bit panel obtains 16.2M colors through a specific algorithm, which is also based on this.
Appropriate control of the frame rate, plus some control of the color between adjacent frames, so that when we watch the dynamic picture on the LCD display, we can also see the color that the LCD display could not display. Of course, all major manufacturers have their own technologies, and there are differences in specific implementation methods and details, so they each have some different names for their own proprietary technologies. In terms of color enhancement, Sharp ’s skill is relatively deep. With the same panel, Sharp ’s product color will be better than most opponents, which is why.
Which LCD monitors are 8bit?
For the average user, the LCD of the 6bit panel is now basically enough, and the pixel dithering algorithm and frame rate control technology can further narrow the gap with the 8bit panel.
The actual comparison and use tell us that there is no significant difference between 16.2M and 16.7M in most applications, and they all do equally well. The advantage of 16.7M color is that it can show a smoother and stable color transition, that is, a gradual transition between colors. 16.2M products often have obvious stepped stripes when expressing gradual changes. On the contrary, 16.7M products are better. a lot of.
Samsung's 193P Plus exhibited at CeBIT last year provided a 16.7M color while maintaining a response time of 8 milliseconds. It can be said that it is a relatively good product combining color and speed. But we also need to know that the difference between this software level enhancement and the 8-bit panel's actual hardware level displaying 24-bit color is still very obvious. In professional situations, the 6-bit panel LCD display does not meet the needs.
16.2M is the enhanced color display capability of the software, while 16.7M is the real physical display capability, and the gap between them is not 500,000 colors. For users who are more concerned about color or have the intention to develop in the direction of professional design, it is recommended to consider an 8-bit LCD monitor.
EIZO uses a 10-bit driver IC in some high-end products to raise the color level of the LCD display to a whole new level
And now it seems that 8bit panel is not the end of the development of LCD in the number of color displays. 1 For professional design users, apart from the traditional CRT, even a 16.7M LCD is not enough. This is why EIZO has developed a 10-bit driver IC specifically for its high-end LCD to meet the high color requirements of professional users.
In terms of demand, Photoshop has long supported RGB 16-bit precision per channel. The definition of true color of 24-bit color may also be eliminated by higher standards in the future.
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