Examples of spectral color in the following topics:
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- The spectrum does not, however, contain all the colors that the human eyes and brain can distinguish.
- The figure above shows this part of the spectrum, together with the colors associated with particular pure wavelengths.
- Colors that can be produced by visible light of a narrow band of wavelengths (monochromaticlight) are called pure spectral colors.
- Quantitatively, the regions of the visible spectrum encompassing each spectral color can be delineated roughly as:
- Note that each color can come in many shades, since the spectrum is continuous.
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- where $B$ is the spectral radiance of the surface of the black body, $T$ is its absolute temperature, $\lambda$ is wavelength of the radiation, $k_B$ is the Boltzmann constant, $h$ is the Planck constant, and $c$ is the speed of light.
- Note that the spectral radiance depends on two variables, wavelength and temperature.
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- This process produces an emission spectrum of x-rays at a few discrete frequencies, sometimes referred to as the spectral lines.
- The spectral lines generated depend on the target (anode) element used and therefore are called characteristic lines.
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- If the range of the power-law distribution is sufficiently large (at least an order of magnitude) we can take $x_1\rightarrow 0$ and $x_2 \rightarrow \infty$ in (23) so that the integral is simply a constant and we find that the spectral distribution is also a power-law $\omega^{-s}$ with a power-law index of $s=(p-1)/2$.
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- Notice that the spectral index does not depend on the power-law index of the particle distribution but rather results from the power-law relationship between particle energy and frequency.
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- The hydrogen spectrum had been observed in the infrared (IR), visible, and ultraviolet (UV), and several series of spectral lines had been observed .
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- Relating the spectral lines and their strengths to particular atoms are their abundances requires a detailed knowledge of the physics of atoms (Chap.8) and their transitions (Chap.9).
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- With human eyesight, cone cells are responsible for color vision.
- From there, it is important to understand how color is perceived.
- Using the cone cells in the retina, we perceive images in color.
- The human eye is more sensitive to intensity changes than color changes, which is why it is acceptable to use black and white photography in place of color and why people can still distinguish everything in the photo without colors.
- You can go from RGB to YUV color spaces with the following matrix operation:
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- We see about six colors in a rainbow—red, orange, yellow, green, blue, and violet; sometimes indigo is listed, too.
- These colors are associated with different wavelengths of light.
- The sequence of colors in rainbows is the same sequence as the colors plotted versus wavelength .
- (There is no dispersion caused by reflection at the back surface, since the law of reflection does not depend on wavelength. ) The actual rainbow of colors seen by an observer depends on the myriad of rays being refracted and reflected toward the observer's eyes from numerous drops of water.
- Even though rainbows are associated with seven colors, the rainbow is a continuous distribution of colors according to wavelengths.
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- A chromatic aberration, also called achromatism or chromatic distortion, is a distortion of colors .
- This aberration happens when the lens fails to focus all the colors on the same convergence point .
- These aberrations or distortions occur on the edges of color boundaries between bright and dark areas of an image.
- Since the index of refraction of lenses depends on color or wavelength, images are produced at different places and with different magnifications for different colors. shows chromatic aberration for a single convex lens.