Silly Image Trickswith a Cameraphone

Adam Smith(amsmith@cs.ucsc.edu)

CCD Tempurature

Comparing cameraphone dark-frames. Top image was taken at room temperature and bottom was taken after holding near a halogen lamp for about 15 seconds, hot! Notice that many red pixels and some green pixels are visible in the hot image (only bottom quarter of dynamic range shown for emphasis).

Painterly Rendering

• Top image was rendered in an artistic style, bottom is original image. Both represent about 160,000 bits of information but very different types of details are emphasized. (8B/stroke * ~50x50 strokes vs 24KB JPEG)

Shutter Phase?

Image was inverted for better visiblilty.

Entire surface of lamp pulses at frequency FL.

Cameraphone shutter time at Tc=1/Fc.

Scrolling color-band pattern has temporal frequency Fc-FL (~0.1Hz) and spatial frequency ??? (~0.02 px-1) – something related to the vertical scan time of the CCD. Actually a high time-resolution sampling of the (partially pre-integrated) light output of the lamp.

This is different than the effect in video of CRTs where and object in the world has a spatially varying signal as well.