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IPhone turns into color calibrator? Apple TV saves you money for a color calibrator

via:博客园     time:2021/4/26 13:52:08     readed:354

At Apple's spring new product launch, Apple TV, which has not been updated for many years, was finally upgraded

  • Processor upgraded to A12 bionic
  • Newly designed Siri remote
  • 4K high frame rate HDR (HDMI 2.1)
  • Color balance with iPhone
  • Gigabit Ethernet, WiFi 6 (802.11ax)
  • Connecting two air pods at the same time
  • Support iPhone remote control
  • Support high frame rate space delivery, and also support Dolby horizon standard
  • Control lighting with homekit


In this series of "regular upgrades", the most surprising may be the new "color balance", which uses the iPhone to automatically calibrate the colors of the TV and automatically generate more balanced color display effects. For Apple TV without "TV screen", it can maximize the most consistent display effect and more accurate and balanced color performance of most TV connected to Apple TV.

How does iPhone do "color correction"

The press conference described in detail how to use the iPhone with Apple TV to complete the whole process of adjusting the color balance

First, enter the settings page of Apple TV, find the video and audio options, and find the color balance option in the calibration section. Apple TV will measure the color response of the TV through this function, and calibrate the output signal to improve the overall image quality. However, it should be noted that when adjusting, try to avoid turning on bright mode or high saturation image mode, such as bright or motion mode. In addition, only iPhone with face ID and IOS 14.5 or above can be calibrated.


After the color balance adjustment is turned on, a blue irregular lattice area will appear on the TV. Now turn the iPhone and point the front camera at the TV. Place the iPhone close to the center of the blue area in the white box, and within an inch of the screen. Make sure the top edge of the iPhone is completely inside the frame( Make sure the sensor is in the frame)


After that, the color measurement program will start automatically, and switch red, green and blue colors in turn. At the end, the gray scale will be tested, and the mobile phone will vibrate and remind you every time you switch a color card.


In this way, the color balance calibration can be completed, and the whole process is very simple and fast. Just put the iPhone close to the screen and it can be completed automatically.


All this is done through the "bangs" of the iPhone. First, the front camera and distance sensor guide the user to aim at the target on the screen and automatically start the color determination process. Then, the iPhone ambient light sensor is used to compare the color balance of the TV with the industry standard parameters, so as to adjust the video output to make up for the difference, so as to eliminate the inaccurate color as far as possible.

Why color correction

At present, everyone's demand for color correction is due to professional needs. For example, designers need a color accurate screen to ensure that the image effect will not be affected by the color deviation of the display. On the other hand, it is necessary to eliminate the color difference between different displays when multi screen splicing, because even the displays of the same brand and model may have color difference. However, there are higher requirements for screen display.

The main reason why Apple TV needs color balance is that although it is called "TV", it does not have a real TV screen, which is closer to the shape of "TV box", so it is generally connected to other TVs or monitors.


This leads to a problem. Due to the differences in gamut and color accuracy of different display devices, it is likely that the colors of the same source will vary greatly on different devices. In order to enable users to see more accurate colors and make different display devices connected to Apple TV have the same color performance, Apple introduced this "color correction" function. The most ingenious thing is that users only need to use Apple's own devices to achieve it, and almost every Apple TV user has an iPhone, which is undoubtedly the most convenient and efficient "color correction" method with the lowest cost for users.

In fact, the whole process and professional screen color correction process is very similar, of course, the accuracy is certainly much weaker. Moreover, the color balance function only supports SDR and HDR 10, not Dolby vision.

At present, most of the color calibrators on the market are colorimeters and spectrophotometer. The former uses a color filter, while the latter uses a grating to decompose the reflected light. In general, the accuracy of colorimeter is not as good as spectrophotometer.

The principle of color calibration is also very simple. It outputs specific color signals and displays them on the required color calibration screen. The sensor of the color calibrator receives the color signals displayed on the screen, generates color parameter files and compares them with the "standard color parameters", so as to make targeted adjustments.


The Datacolor Spyder x color calibrator

The principle of the ambient light sensor on the iPhone is similar to that of the color calibrator, but the incident light is separated into different colors by an optical device, and then passed through several filters to receive the color signal.

Most of the models after iPhone x use AMS multispectral sensors, which can sense a wide spectrum. Combined with the diffuser, they can sense ultraviolet, red, green, blue and two kinds of near-infrared light. Since it can receive the ambient light, it can also receive the light of the screen when it is close to the screen, and then transmit the obtained information to Apple TV.


Therefore, as early as the release of iPhone x, it was already feasible to use the ambient light sensor for simple "color correction". This may be another major use of this sensor in addition to supporting "original color display".

However, at present, apple only uses this function to adjust the output signal of Apple TV, rather than the display parameters of the display, so the color of the display can't be more accurate. After switching to other input sources, it can't guarantee whether the color is still accurate.

Although it is not known how the real "color correction" effect will be, for Apple TV, the "TV box", this may be the simplest and most convenient solution to ensure that the color display effect of different TVs will be more consistent after they are connected to Apple TV.

There's a lot of room for imagination

This use of ambient light sensor for TV "color correction" function, also let me get a lot of inspiration.

In the past, the main purpose of ambient light sensor or color temperature sensor in electronic products is to detect the color temperature in ambient light, so as to adjust the display effect of the screen to achieve the most comfortable feeling for human eyes.


Another large-scale application is that it can help improve the color restoration degree of photos, so as to reduce the effect of color deviation caused by ambient light.


If this sensor is called by a third-party software, a large number of "color calibrator" tool apps may appear first to simply "color calibrate" other display devices. After all, most flagship models are equipped with color temperature / ambient light sensors as standard.

In addition, you may be able to use the color temperature sensor on the mobile phone to adjust the light by connecting the mobile phone app with the desk lamp / screen lamp. Just as the mobile phone is also on the desktop, it's easy to make the whole process automatically senseless, which is very helpful for improving the experience of smart home.


However, these are just my imagination. It is uncertain whether the ambient light sensor on the mobile phone will realize these applications in the future. More and more electronic products are added to the color temperature sensor is also a good trend, so the realization of these functions seems to have become less important.

Finally, the good news is that the current old versions of Apple TV 4K (2017) and Apple TV HD (2015) have also updated the "color balance" calibration function, which will be released in tvos 14.5 next week.


If you are using an old version of Apple TV, try this "color balance" function to see how much improvement it has.

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