algorithms. The first step, called demosaicing,
interpolates the RGB values for each pixel in
the image based on the pattern of colors in
the microlens array. The distance between the
microlenses and the converter pixels located
behind them is then compensated for by
rotating the two-dimensional image by a
maximum of 0.1 degrees. In the third step, the
resulting pixels are again interpolated to
produce a number of pixels per microlens that
can be divided by a discrete number. Next, the
two-dimensional data from the sensor is
distributed to form a matrix of sub-images.
The penultimate step involves refocusing – in
other words, addition and shifting of the
sub-images using ‘supersampling’ techniques
and quadrilinear reconstruction filters. Finally,
the finished image is separated from all the
unwanted rays surrounding it using a digital
vignetting process.The Lytro
The Lytro is a fully functional consumer light
field camera. It is small enough to be held in
the palm of your hand, even though it has an
8x zoom lens and a CMOS analog-to-digital
converter with an array of microlenses built in.
The camera is supplied with a USB cable and
a quick start guide, and software for importing
and viewing images on Mac computers is
stored in its built-in memory. A Windows
version is available as well.
Even the appearance of the camera
underscores its completely new approach to
photography. The camera body is 4.41 inches
(112 mm) long and 1.61 inches (41 mm)
square in section. The rear end houses a
38.5 mm square touchscreen LCD display that
also doubles as the camera’s control panel.
The 8x zoom lens has an equivalent range of
43-350 mm and is zoomed by moving your
finger over the sensor strips on top of the rear
portion of the camera body. The currently
selected zoom setting is indicated on the LCD
screen. Pressing the shutter release button on
the top of the camera captures the view
shown on the screen as a light field, and the
camera automatically displays versions with
different planes of focus on the tiny display.
The touchscreen uses swipe gestures to
access the menus and switch to playback
mode or display the current battery charge
level and the amount of free memory. You can
also use it to switch between Everyday and
Creative shooting modes. In Everyday mode,
the refocus range (i.e., the distance between
foreground and background objects that can
be refocused) is set automatically, whereas in
Creative mode, tapping an object within the
frame sets that object as the middle of the
refocus range. The Lytro does not have aLight Field Photography | The Lytro
The camera’s tiny touchscreen display doubles as its control panel but can be difficult to
view from an angle. Moving your fingertip over the grooves in the gray part of the camera
body zooms the lens.A B C D E FGThe main components of the Lytro in cross-section:
A:ˇ 8 xoptical zoom lens, B:ˇMicrolenses, C:ˇConverter chip, D:ˇProcessor board,
E:ˇBattery, F:ˇDisplay board, G:ˇTouchscreen