...they colored the images
Just a clarification. It's not colorized in the way you would add color to an old black and white photo. The three black and white images taken through different primary colored filters essentially form primary color channels that can be combined to produce the color image. It's similar to how the sensor works in your digital camera. That sensor records grayscale intensity (i.e. luminosity) through primary colored filters also. Instead of three separate exposures, the sensitive spots on the camera's sensor are arranged in a matrix that allow recording the luminosity through primary color filters. Knowing the color of the filters, the color of the object can be reconstructed.