images

_config.yml

@@ -15,5 +15,5 @@ callouts:
     title: Note
     color: purple
 
-url: https://quentinbolsee.pages.cba.mit.edu
-baseurl: mas865.24_computer-vision
+# url: https://quentinbolsee.pages.cba.mit.edu
+# baseurl: mas865.24_computer-vision

topics/01_cameras/index.md

@@ -127,11 +127,27 @@ The image plane is an imaginary construct sitting in front of the sensor, at one
 
 It is common to choose the $z$ axis to point **toward** the scene, and the $y$ axis to point downward. This matches the conventional downward-pointing vertical coordinates in pixel coordinates, with $(u,v)=(0,0)$ in the top-left corner.
 
-## CCD
+## Technologies
 
-## CMOS
+We'll focus on the two main families of digital sensors: CCD and CMOS.
 
-## Bayer pattern
+In both families, the actual light sensing is based on the electron-hole pair generation in MOS devices.
+
+### CCD
+
+In CCD sensors, the generated charges in the photodiodes are accumulated under a potential well, controlled by a voltage on the gate.
+
+Charges can be moved to a neighboring pixel by performing a specific sequence on the gates. By shifting the charges all the way to the edge of the sensor, individual pixel values can be readout sequentially.
+
+Advantage of CCD sensors include the simplicity of their design, and the large surface dedicated to sensing light. One disadvantage is the readout speed bottleneck caused by using a single decoding unit.
+
+### CMOS
+
+## Bayer filter
+
+![](img/bayer.png)
+
+<!-- source:https://en.wikipedia.org/wiki/Bayer_filter -->
 
 # Lens
 
@@ -139,14 +155,30 @@ It is common to choose the $z$ axis to point **toward** the scene, and the $y$ a
 
 ## Distortion
 
+![](img/lens_distortion.png)
+
 # Aperture
 
+![](img/aperture.png)
+
+<!-- source:https://www.adorama.com/alc/camera-basics-aperture/ -->
+
 # Shutter
 
 ## Mechanical shutter
 
+![](img/shutter.gif)
+
+<!-- source:https://www.youtube.com/watch?v=CmjeCchGRQo -->
+
 ## Electronic shutter
 
 # Photography basics
 
-## The 3 parameters: shutter speed, aperture, ISO
+## The 3 parameters
+
+- Aperture
+- Shutter speed
+- ISO
+
+Each parameter can be converted to a $\log_2$ scale. A common name for a unit on that scale is a **stop**. For example, increasing exposure by one stop can be achieved by doubling the shutter speed, doubling the ISO or increasing the aperture by $\sqrt{2}$.