Comparing spectral distributions within the scene
In the previous depiction, we considered the pattern of energy across the image at a given wavelength. Here, we will instead consider the pattern of energy across the visible wavelengths (the spectrum) at particular positions within the image.
Use your mouse to position the cursor over a point of interest in the image of the scene. Then, press a number between 1 and 6 on your keyboard. You will see a number appear at the position of the cursor, to indicate where you placed the number, and the graph below the image will update to show the spectrum for that particular pixel. In this way, you can use the graph to compare the spectra of up to six locations in the image.
If you would like to clear a particular number, press the associated key with the mouse cursor outside of the image. If you would to clear all of the numbers, you can press the x key.
Next, we will consider how the photoreceptors in your eye respond to the scene.