Annotations

Types of Annotation

  1. Draw lines
  2. Draw Circle
  3. Draw rectangles
  4. Add text

Draw Lines

  • imgout = cv2.line(img, pt1, pt2, color[, thickness[, lineType[, shift]]])
    • img : input image on which annotations have to be performed
    • The line segment to be drawn will have 2 vertexes : (x1,y1) & (x2,y2)
    • pt1 : first point (x1,y1)
    • pt2 : second point (x2,y2)
    • color : colour of the line segment being drawn
    • thickness : Integer specifying the line thickness.
      • Default value is 1.
    • lineType : Type of the line.
      • Default value is 8 which stands for an 8-connected line.
      • Usually, cv2.LINE_AA (antialiased or smooth line) is used for the lineType.
        • other types are : cv2.LINE_8 , cv2.LINE_4

          Draw Circles

  • img = cv2.circle(img, center, radius, color[, thickness[, lineType[, shift]]])
    • thickness : if negative value is given, it will result ina filled circle.

Drawing Rectangle

  • img = cv2.rectangle(img, pt1, pt2, color[, thickness[, lineType[, shift]]])
    • pt1 : top left vetex
    • pt2 : bottom right-vertex

Adding text

  • img = cv2.putText(img, text, org, fontFace, fontScale, color[, thickness[, lineType[, bottomLeftOrigin]]])
    • org : Bottom-left corner of the text string in the image.
    • fontFace: Font type
    • fontScale: Font scale factor that is multiplied by the font-specific base size.
      • if negative then upside down text

Collab Notebook here