No - go check out that Wikipedia link about Bayer filters. For the vast majority of cameras, if you buy a "4 megapixel" image sensor, you get 1 million red pix

No - go check out that Wikipedia link about Bayer filters. For the vast majority of cameras, if you buy a "4 megapixel" image sensor, you get 1 million red pixels, 2 million green pixels, and 1 million blue pixels. When you load the image into your image editor and see 3 colours per pixel, 2 of the 3 are interpolated from neighbouring pixels.