How to changing led color temperature ?

How to changing led color temperature ?
Everyone know that led can adjust light and color temperature. the light control and adjust led light are already familiar .what was the matter with changing led color temperature.

We are take the ceiling light for example. the ceiling light has two channel to output. one channel is warm light(color temperature as 3000k), other channel is cool light(color temperature as 7000k).the two channel are all individuals and should be treated as such. the controller via output different sizes light for echo channel, can be controlled during the whole color temperature output process. for example: A channel is warm light and color temperature is 3000k,but light PWM will output only 10%,
in addition B channel is color light,but light PWM will output also only 40%,the two channel put together mixes of 3000k and 2000k,the ceiling light gained a new color temperature.