CS178 Assignment 8 - Portraits and Light

A studio-lit portrait of Andrew. Photo by Elena Adams.


People are certainly one of the most interesting and most challenging subjects to photograph. For this last assignment, you'll be using all of the skills you've learned during the course to take some stunning portraits. You will need to think about lighting, backgrounds, depth of field, composition, and color. You can also (tastefully) touch up each photo in Photoshop. By now these skills should come quite naturally to you, so you can focus your creative effort on capturing something truly unique or special about your portrait subject.

If you find yourself without anyone willing to model for you this week, you can take a self-portrait for any of the requirements. This is an interesting type of photograph in its own right, and adds a degree of difficulty.

Like last week, there are also a set of exam-style questions at the end of this assignment. Although we will not grade these, they will exercise your understanding of photographic lighting and help you to prepare for the final exam. The answers to these questions will be posted on Wednesday, Jun 6 after the assigment is due.


This week there are five photographic requirements. Requirements 1 through 4 must be met by taking pictures of human beings. (Sorry, no portraits of pets, stuffed animals, etc. this week!) Requirement 5 can be met using any subject of your choosing.


  • Requirement 1: Indoor Traditional Portrait
    Take a portrait of someone using a traditional portait lighting setup as described in lectures (a key light, a fill light, and possibly a background light and accent/rim light). Unless you have some fancy lighting gear of your own, you should take this picture during your regular section meeting where we will set up a full studio lighting kit.
  • Requirement 2: Indoor Natural Light Portrait
    Take a portrait of someone indoors using only non-electric sources of light (a fireplace, candles, the sun, etc). You might want to arrange someone near a window. Think about the light in the same way as for the studio lighting, and comment on how you created a fill light, how you created a key light, etc.
  • Requirement 3: Outdoor Available Light Portrait
    Take a portrait of someone outdoors under available lighting only. Comment on what serves as the fill light and key light. If you like, you can also make this one a candid shot, in which the subject is not aware you're taking a photo (or at least appears to not be aware).
  • Requirement 4: Flash + Ambient
    Take a portrait which uses a combination of your camera's flash and ambient illumination. Again, comment on what serves as the key light and what serves as the fill light. Remember, you need not point the flash right at the subject - with a small hand-held mirror or white card you can bounce any camera's flash elsewhere.
  • Requirement 5: Non-photorealistic Photograph
    This requirement is unrelated to portraiture, but we thought it would be fun now that you are all experts at image editing. Use a single photograph or combination of photographs to create a single, non-photorealistic image in Photoshop. This requirement is wide open to your creative interpretation, but result must look substantially non-realistic in some way. As a hint: you may want to try taking photographs under multiple different lighting conditions (e.g. at different times of day & night, or flash/no flash with unusual processing); or you may try stitching together pictures of your subject from multiple viewpoints. You may find some inspiration in the artwork of cubists, or the photographic works of David Hockney and Jeremy Kidd.

Upload your photos and add comments.

Upload your photos using the Picasa account you created in the first week to a public Picasa album titled "CS178 Assignment 8 - Portraiture". Write at least two short paragraphs (ie two picasa comments) below each of your photos explaining how you arranged the scene, how you took the photo, what relevant camera settings you used and why, any image processing done to the photograph afterwards, and most importantly, which requirement the photo covers.

Example Solution

As usual, we've posted an example solution to this assignment to let you know what we expect. For additional inspiration, you may want to peruse the best CS178 photographs (as selected by the TA's and instructor) from 2009 , 2010 , and 2011. However, you do not need to meet the assignment requirements in the same way as these solutions do - in fact, you should challenge yourself to come up with creative, unique compositions. There are plenty of possibilities out there. Surprise us!

Please remember that the photographs that you submit for each assignment must be taken by you specifically for this course. Do not reuse old photographs that you may have laying around, even if they perfectly meet one of the requirements!

If you have questions or comments about the photos we used in the example solution, feel free to add them as comments below the corresponding photograph in Picasa Web, or to email us.

Practice problems

These questions are for your own educational benefit; you do not need to submit your answers. After the assignment is due we will select the correct answers in bold. This is the last set of practice problems (besides Final Review) that we will give out before Finals, so please make sure to do these problems on your own.

  • Problem 1a.Betelgeuse is the second brightest star in the constellation Orion (it's Orion's right shoulder). The surface of Betelgeuse has a temperature of about 3500 Kelvin (5840 Farenheit), and for this question you should assume stars are perfect blackbody radiators. If you were to take a photograph of Betelgeuse with your white balance set to daylight (6500 Kelvin), what color would Betelgeuse be in the photo?
    • a) Reddish
    • b) Greenish
    • c) Blueish
    • d) Whitish

  • Problem 1b. What color would Betelgeuse appear if you instead set the white balance to tungsten (3200 Kelvin)?
    • a) Very red
    • b) Slightly red
    • c) Slightly blue
    • d) Very blue

  • Problem 2a. As every scout knows, you can start a fire on a sunny day by focusing the sun's image on a piece of paper placed on the ground. ---------(Warning: If you rush out to test this, be careful! Never look at the sun directly, never hold a magnifying glass between your eye and the sun, and never look directly at its focused spot on a white surface. Sunglasses are not enough to protect you from doing any of these things. Glacier goggles or welder's helmets are sufficient for brief glances at the white surface, but not at the sun.) Is the luminance of the sun as seen from the focal point of the lens (where the light rays converge, at the piece of paper) more, less, or the same as the luminance as seen from same point in the absence of the magnifying glass? Select the correct choice:
    • a) more than
    • b) less than
    • c) the same

  • Problem 2b. Is the luminous intensity at the focal point more, less, or the same as the luminous intensity at the same point in the absence of the magnifying glass? Select the correct choice.
    • a) more than
    • b) less than
    • c) the same

  • Problem 2c. Is the total luminous power (in lumens) reaching the entire piece of paper more, less, or the same as the power reaching the paper in the absence of the magnifying glass? Select the correct choice. Assume the piece of paper is much larger than the magnifying glass.
    • a) more than
    • b) less than
    • c) the same

  • Problem 3. True or False: You can think of a diffuse (or Lambertian) surface as being made of a bunch of tiny reflectors, all basically lying flat across the surface of the object.

  • Problem 4. True or False: To verify the claim that, on a sunny day with a blue sky, shadowed areas should be about 1/5 as bright as non-shadowed areas, you can take a JPEG image and measure the ratio of pixel values in those two areas.

  • Problem 5. Simple demosaicing algorithms based on linear inter\ polation are likely to fail on which of the following scene subjects? Circle a\ ll that apply.
    • (a) A bright orangewall
    • (b) A picket fence 50 feet away
    • (c) A fabric with thin stripes on it
    • (d) A transclucent green vase
    • (e) None of the above scenes will cause problems.

  • Problem 6.If a spotlight has a uniform radiant intensity of 10 W/sr over its whole cone of light, and the cone subtends 2 steradians, how much total power will fall on a large white wall 10 meters away when the spotlight is pointed at it? Assume the wall is larger than the lit area created by the spotlight. Circle the best answer.
    • a) 5W
    • b) 10W
    • c) 20W
    • d) 40W
  • Problem 7.If you want to bring out the most detail in a rough surface, you should light it with (circle the best answer):
    • a) grazing light
    • b) direct light
    • c) spotlight
    • d) diffuse light


We will assign grades based on whether you met the requirements of the assignment. For each requirement, you'll be given a check for meeting the requirement, check-minus for not quite meeting the requirement, or check-plus if you do something spectacular that makes your grader's jaw drop.

Due Date

11:59PM, Wednesday, June 6, 2012

Please Note: We will accept no late assignments or replacement photos after midnight on Sunday June 10. Be sure to read the lateness policy from the course outline, or contact your TA if you have any questions. © 2009-2012 Marc Levoy, Andrew Adams, and Jesse Levinson