What is the Computer Vison

Computer Vision is the process by which a machine or a system generates an understanding of visual information by invoking one or more algorithms acting on the information provided.

The understandings are then translated into decisions, classifications, pattern observation, and many more.

Chanllenge of CV

• Feature extraction is difficult
• Large amount of calculation

CNN

A Convolutional Neural Network (CNN) is a Deep Learning algorithm which can take in an input image, assign importance (learnable weights and biases) to various aspects/objects in the image and be able to differentiate one from the other.

Category of CV

• Image classification Image Recognition is the task of identifying objects of interest within an image and recognizing which category they belong to.
• Object detection
  Object detection is a computer vision technique that allows us to identify and locate objects in an image or video.
• Semantic segmentation Semantic segmentation is the task of clustering parts of an image together which belong to the same object class.
• Instance segmentation Instance segmentation is the task of detecting and delineating each distinct object of interest appearing in an image.
• Video classification Video Classification is the task of producing a label that is relevant to the video given its frames.
• Human key point detection Human Pose Estimation is defined as the problem of localization of human joints (also known as keypoints - elbows, wrists, etc) in images or videos.
• Scene text recognition Scene text recognition is the task of recognizing character sequences in natural scenes.
• Target tracking Object tracking is the task of taking an initial set of object detections, creating a unique ID for each of the initial detections, and then tracking each of the objects as they move around frames in a video, maintaining the ID assignment.
• More Multimodal learning suggests that when a number of our senses - visual, auditory, kinaesthetic- are being engaged during learning, we understand and remember more.

What is Image

Definition: a visible impression obtained by a camera, telescope, microscope, or other device, or displayed on a computer or video screen.

• Binary Images

  • In a binary image,each pixel assumes one of only two discrete values.
  • Essentially, these two values correspond to on and off.
  • A binary image is stored as a logical array of 0’s (off pixels) and 1’s (on pixels).

• Color Space

  • 3 Channels: Red Green Blue
  • Black: (0,0,0), White: (255，255，255)

  

• HSL and HSV

  

  

OpenCV

OpenCV (Open Source Computer Vision Library) is an open source computer vision and machine learning software library.

• Color Preset Mode of OpenCV–>BGR, transfer to RGB: cv2.cvtColor(imgname, cv2.COLOR_BGR2RGB)

• RGB to Grey scale: cv2.cvtColor(imgname, cv2.COLOR_BGR2GRAY)