Reference

API Description

  /**
   * @brief  Set the ALS gain 
   * @param  aGain  the value of gain
   */
  void setALSGain(uint8_t aGain);

  /**
   * @brief  Set the internal integration time of the  four-channel ADCs
   * @param  aTIme  integration time
   */
  void setIntegrationTime(uint8_t aTime);

    /**
   * @brief  get channel 0 value
   * @return  the z data
   */
  uint16_t getZData();

  /**
   * @brief  get channel 1 value
   * @return  the y data
   */
  uint16_t getYData();

  /**
   * @brief  get channel 2 value
   * @return  the IR1 data 
   */
  uint16_t getIR1Data();

  /**
   * @brief  get channel 3 value
   * @return  the x data
   */
  uint16_t getXData();

  /**
   * @brief  get channel 3 value
   * @return  the IR2 data
   */
  uint16_t getIR2Data();

Working Principle of XYZ Tristimulus Color Sensor

Devices with True Tone technology like Apple iPad Pro, iPhone, and Macs usually feature sensors that measure the ambient light colour and brightness. The device then uses this information to automatically adjust its display, so it can correct white points and illumination based on your environmental lighting in order to render the right kinds of white under any conditions. And XYZ Tristimulus Color Sensor plays an important role in this technology.

TCS3430 features advanced digital ambient light sensing(ALS) and CIE 1931 tristimulus color sensing(XYZ). CIE1931 XYZ Tristimulus model is a kind of standard based on three different human cone cell types. The CIE XYZ color space encompasses all color sensations that are visible to a person with average eyesight. The spectral response of TCS3430 is almost the same as that of human eyes, which can realize the high-precision measurement of illumination and color temperature. What you see is what you measured!
The TCS3430 Tristimulus Color Sensor is ideally suited for the use in smartphone applications to improve color measurement and intensity of ambient light conditions. Also, it can be used in scenarios requiring a true-color viewing experience like online shopping(product color matching, reducing the return rate caused by color difference of images and real product).

You can learn more about CIE 1931-XYZ system here: https://en.wikipedia.org/wiki/CIE_1931_color_space