CS178 Assignment 8 - Portraits and Light

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

Motivation

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 Sunday, May 29th after the assigment is due.

Instructions

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.

Requirements

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 and 2010. 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.

Grading

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 1, 2011

Please Note: We will accept no late assignments or replacement photos after midnight on Sunday June 5. Be sure to read the lateness policy from the course outline, or contact your TA if you have any questions.

Practice technical questions

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.

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?

Reddish

Greenish
Blueish
Whiteish

1b) What color would Betelgeuse appear if you instead set the white balance to tungsten (3200 Kelvin)?

Very red
Slightly red
Slightly blue

Very blue

2a) Match the materials listed below with the gonionmetric diagrams at http://graphics.stanford.edu/~abadams/goniometric.png. Firstly, glossy black plastic:

Diagram A
Diagram B
Diagram C

Diagram D

2b) Glossy white plastic

Diagram A
Diagram B
Diagram C
Diagram D

2c) White matte paper

Diagram A
Diagram B

Diagram C
Diagram D

2d) Black matte paper

Diagram A

Diagram B
Diagram C
Diagram D

3) Last night I took a digital photograph of the moon. This morning the Stanford Daily reported that the moon had left its orbit and was on a collision course with Earth. By tonight it will be half the distance from the earth that it was last night. How should I adjust my camera so that the moon's surface will be the same value in each pixel of tonight's photograph as it was last night? Circle the best answer. Assume the moon is homogeneously colored across its visible surface.

(a) Double the exposure time
(b) Halve the exposure time
(c) Leave the exposure time alone

(d) Multiply the exposure time by sqrt(2)
(e) There is a correct adjustment, but none of the above answers is correct
(f) There is no adjustment that will work; you cannot match the pixel values

4a) 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:

more than
less than
the same

4b) Is the luminous intensity at the focal point more, less, or the same as the luminance at the same point in the absence of the magnifying glass? Select the correct choice.

more than

less than
the same

4c) 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.

more than
less than
the same

5) Total luminance can be expressed as the sum of the human tristimulus responses ρ, β, γ.

True

False

6) 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.

True
False

7) 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.

True
False