Search results

  1. A

    What causes the green penumbra in this picture?

    Yes. It was in total darkness.
  2. A

    What causes the green penumbra in this picture?

    If the illumination of the background of the white screen by a mix of white and green is interpreted as "white" and other shadows as colored, then this effect should disappear when this background screen is hidden. Like when I cute another piece of black paper and fit it on the white screen but...
  3. A

    What causes the green penumbra in this picture?

    That is exactly what I observed when I used a green and white LEDs ( see the picture). The shadow toward the white LED (on the right side of the picture) appears red as intuitively expected. This is clear by both naked eyes and by the camera. If the brain interprets the mix of the green and...
  4. A

    What causes the green penumbra in this picture?

    So what do you expect if I use green and white LEDs instead of red and white LEDs? Will the shadow that appeared green in the previous example be green too?
  5. A

    What causes the green penumbra in this picture?

    Thank you for showing me how the camera can modify the colors of the scene. But I even noticed that by my naked eyes before using the camera. I thought of a retinal compensation, but this may work in a narrow interface between two areas (something similar to Mach effect) unlike my observation...
  6. A

    What causes the green penumbra in this picture?

    If the green shadow is due to the light source, the exposed white paper with the white source only would yield a green hue too. I exposed a blank white paper with the white LED and I used some apps to roughly measure the color of the area exposed to the white LED and I compared it with the...
  7. A

    What causes the green penumbra in this picture?

    I tried with other material and I got the same effect.
  8. A

    What causes the green penumbra in this picture?

    I exposed a black bottle cap by two light sources ( LEDs), one source is white and the other one is red as in the picture. I noticed that one penumbra toward the red light source is reddish in color which makes sense because this area is only exposed to the red source. What makes a puzzle is the...
Top