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CSCE 489/689 – Computational Photography Assignment 1

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CSCE 489/689 – Computational Photography
Assignment 1

1 Goal
In this project, you will work in groups of at most 5 to design a pinhole camera. All the team members
get the same grade. The pinhole camera (also called the “camera obscura”) is essentially a dark box with a
pinhole on one face and a screen on the opposite face. Light reflecting off an object is directed through the
pinhole to the screen, and an inverted image of the object forms on the screen. The caveat is that it is hard
to see the image formed with the naked eye. To be able to see the image, we will use a digital camera with
a long exposure time (15-30 seconds) attached to the pinhole camera. A diagram of the setup is shown in
Fig. 1.
2 Task 1
Follow the steps below to build your pinhole camera:
• Find a cardboard box. It does not have to be too big, but it does have to ultimately be “lightproof”; a
shoebox will work fine. The cardboard box should be such that the distance between the pinhole and
the screen is longer than the minimum focus of the digital camera, so you do not get a blurry image.
• Obtain a digital camera with the ability to capture images with long exposure time (15 to 30 seconds).
While forming your teams, you should figure out who has a digital camera with long exposure time.
If no one in your group has such a digital camera, we have a limited number of high-end cameras that
you can borrow by contacting Bruce Veals at [email protected] Note that, to borrow a camera,
your group should have 5 members.
• Determine which face of the box should be your screen. Cover the inside of this face with white
paper; printer paper is fine.
• Cover the rest of the faces on the inside with black paper. Use duct tape (best to use black tape) to
make sure the papers are stuck to the box.
• Create the pinhole on the opposite face of the screen. Putting the pinhole directly on the cardbox
is not a good idea since 1) the cardboard is thick which limits the field of view of your camera and
2) this design is not flexible and won’t let you try capturing images with different pinhole sizes. To
alleviate this issue first cut a hole in the box and cover this hole with card paper. The pinhole will be
punched into the card paper. This way you can change your pinhole by changing the card paper.
• Next to the hole for the card paper, cut a hole for the digital camera’s aperture. The camera aperture
should fit snugly into the hole, so the light doesn’t get in. The digital camera’s hole should not be
too far from the pinhole, since the camera’s field of view may not be wide enough to capture the
screen’s image: you may have to angle the digital camera a bit towards the pinhole. Figure out the
appropriate settings for the digital camera (i.e., long exposure time), and make sure it is charged and
has a memory stick before you duct tape it.
• Duct tape your box (black tape is the best) to make your box light proof.
1
Pinhole
Screen
Camera
Scene
Figure 1: Pinhole camera
3 Task 2
Follow the steps below to capture images using your pinhole camera
• Take the setup to a nice sunny area.
• Point the pinhole in the direction of an object of interest.
• Set up the digital camera so that it will capture a long exposure image.
• Shoot, and hold still for 15-30 seconds. The exposure time depends on the brightness of the scene
and the size of the pinhole.
Use three size of the pinhole, e.g., 1 mm, 3 mm, and 5 mm. Note that, these are just suggestions. The
point is to capture images with small, medium, and large pinhole sizes. You don’t need to measure the
diameter of the hole to be exactly these values. Make your design so that you can easily switch between
card papers with different hole sizes. For all three pinhole sizes capture two scenes (6 images). Also capture
an image of the scene with your cellphone to be able to compare it to your captured images.
4 Extra Credit
• Perform light painting. You can use the camera (not the pinhole one) to capture these images. Show
two examples.
• Build stereo pinhole camera to create an anaglyph image.
5 Write up
For each scene include four images (three images for the three pinhole sizes and an image of the scene with
cellphone camera) in your report. You need to analyze the images by discussing the effect of the pinhole
size on the image quality and required exposure time. You should also include images of your pinhole
camera itself. If you do any of the extra credit items, you need to include and discuss them in your report.
6 Graduate Credit
Graduate students have to do both extra credit items to get the full credit.
7 Deliverables
For this assignment you only need to submit a report in the pdf format. Make sure you have written the
name of all your team members on top of the report. You will lose 5 points if you fail to do so. Submit the
report through this Google form.
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8 Ruberic
Total credit: [100 points]
[40 points] – Designing the pinhole camera
[40 points] – Capturing images of two scenes with three different pinhole sizes
[20 points] – Analyzing the results
Extra credit: [10 points]
[02 points] – Light painting
[08 points] – Stereo pinhole
9 Acknowlegements
This project is derived from Alexei A. Efros Computational Photography course with permission.
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