... reflected, and perceived by passersby.
reflected or transmitted
Ink doesn't create its color the way paint does. Paint is opaque. Light hits the surface of the paint film, the wavelengths of light that don't correspond to the color your thing is are absorbed. Ink that isn't black is transparent. Really it is. Light passes through it and strikes the paper surface. The paper absorbs certain wavelengths of light. Then the light passes back through the ink film where the wavelengths not needed for the color of ink are absorbed. A cream-color paper will absorb different wavelengths than a blue-white paper.
First, you must understand that all color is determined by red blue and yellow light in different combinations. Any color is caused by light being reflected off the object. A red object for example reflects red light, and absorbs blue and yellow.
Earth...I think
The light from the sun, which is made up of equal parts of red, green and blue (even though it may not look it), will be reflected off of the white surface, staying white as the white surface reflects equal parts of red, green and blue.
reflected or transmitted
When white light strikes a red object, the object would appear red. The object would have reflected the red light within the white light while all other colours would have been absorbed. When blue light strikes a red object, it would appear black as there is no red light in blue light as it is a primary colour. As a result, the blue light would be completely absorbed by the red object. So no light would be reflected from the object. When violet light strikes a red object, it would appear red, as violet is a combination of blue and red light. The blue light would be absorbed while the red light would be reflected. It is good to learn and revise the light spectrum and primary and secondary light colours. Primary light colours are: Red, Green and Blue Secondary light colours are: Yellow, Cyan and Violet The combinations are: Red + Green = Yellow Green + Blue = Cyan Blue + Red = Violet (or Magenta depending on how you have been taught)
Any opaque or translucent surface will reflect light rays. The rays that are reflected are the one that you see- something blue would reflect blue light. IF the object is Opaque the rest of the light is absorbed. If it is translucent some light is absorbed while some passes through. Black objects absorb all colours of light while white objects reflects all colours of light. There are also some special objects such as mirrors that are highly reflective a produce an image by reflecting back the rays of light emitted from other objects.
Grass looks black in blue light, because blue is an opaque color and green color absorbs it
Blue
Ink doesn't create its color the way paint does. Paint is opaque. Light hits the surface of the paint film, the wavelengths of light that don't correspond to the color your thing is are absorbed. Ink that isn't black is transparent. Really it is. Light passes through it and strikes the paper surface. The paper absorbs certain wavelengths of light. Then the light passes back through the ink film where the wavelengths not needed for the color of ink are absorbed. A cream-color paper will absorb different wavelengths than a blue-white paper.
This is due to the diffraction of the light.
All the light is absorbed, except that portion of the spectrum matching the object's color. That particular bandwidth is reflected. Hence a yellow object appears yellow, and a blue object appears blue. Black objects absorb light without reflecting any, while white objects reflect almost all the visible light which strikes them. The object may then emit the absorbed energy in the infrared spectrum (heat).
Blue. That's why people call it a "blue surface" ... because any other color of light that hits it is absorbed, and never scattered or reflected to your eye.
When green light is shined onto a blue surface the color that reflects back into your eye is a dark Greeny Brown this is because all of the other colours of the spectrum are absorbed.
Depending on the range of wavelengths that comprise the incident light, some of it may be absorbed and some may be reflected. If blue wavelengths are present in the incident light, then the blue is mostly reflected, and any other wavelengths are mostly absorbed. This is the main reason that the surface acquires the reputation of being 'blue'.
If you mix all the colours as lights (red light plus green light plus blue light etc) then you get white light but if you mix all the colours together as opaque pigments or paints then you get black.