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Homework Problems
1) Given an RGB color
[.3, .1, .8], what is the equivalent YIQ color?
[.2396, -.1062, -.2375]
2) If the maximum intensity
of a real image to be quantized, with 5 bit depth resolution, is 1.0 and the
minimum intensity is 0.0, what will be the quantized value for a pixel whose
real intensity was 0.226 ?
Lmin = imin * rmin and Lmax = imax * rmax
3) If you had an image
with spatial resolution of 32 x 64 pixels and depth resolution of 5 gray levels,
how would create an equivalent image with only 2 gray levels? What would be
the required spatial resolution of this created image?
Increase the resolution to 80 X 160
4 a) The vast majority of photo receptors in the human eye are rods.
b) The color discriminating light receptors in the human eye are the cones.
c) Scotopic vision is
a function of the rod receptors.
5) What are the minimum
and the maximum light levels that can be perceived by the human eye?
The range of light intensity levels to which the human visual system
can adapt is enormous, on the order of 10^10 from the scotopic threshold to
the glare limit.
6) Convert the CYM color [.25, .5, .37] to the equivalent CYMK color.
CYMK = [0, .25,
.12, .25]
7) A given digital video image has a spatial resolution of 720 x 486 pixels. It also has a color depth resolution of 12 bits. How many bytes of data are required for this image? (Note - in this image the color information is encoded as 8 bits for the Y intensity and 4 bits for the IQ color data)
(720X486)*(12bits/8bits) = 524,880
8) Given the histogram of an image, how would you calculate the standard deviation for the image?
The histogram shows the values of all the pixels in the image.The mean is
the average values of the pixels. With the mean the varience can be found,
and with the square root of the varience, the standard deviation can be calculated
to measure the range of pixel intensities.
9) If the illumination for a surface is 600 ft-candles and the reflection coefficient of the surface is .35, how much light is reflected from the surface? (i=illumination, r=reflection)
f(x,y) = i(x,y)
*r(x,y)= 600 *.35 = 210 ft-candles
10) Find and describe an application that is based on extracting specific information from digital images. What kind of image information is used in this application?
In medicine, one application of using digital images is enhancing pictorial information for human interpretation and analysis. Examples of this range from x-rays, to CAT scans, to ultrasounds. For each of these, some computer based technology takes/scans the original info, and converts it into 2D or 3D images making it easier to understand. Computers do this by enhancing the contrast or coding the intensity levels into color for easier interpretation .