[OpenCV/Python] 도형 그리기(line, rectangle, clipLine, circle, ellipse, polylines, ellipse2Poly, fillConvexPoly, fillPoly)

OpenCV 도형 그리기

import cv2
import numpy as np

# line

cv.line(img, pt1, pt2, color[, thickness[, line_type[, shift[, tipLength]]]]) ->img

 

Parameters

img	Image.
pt1	The point the arrow starts from.
pt2	The point the arrow points to.
color	Line color.
thickness	Line thickness.
line_type	Type of the line.
shift	Number of fractional bits in the point coordinates.
tipLength	The length of the arrow tip in relation to the arrow length

 

# White 배경 생성 및 pt1-pt2(Red), pt1-pt2(Blue)을 잇는 선 그리기

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255  # 흰 배경이미지 생성

# 꼭지점 지정
pt1 = 0, 0 
pt2 = 500, 0
pt3 = 0, 500

# blue_color = (255, 0, 0) 
# green_color = (0, 255, 0)
# red_color = (0, 0, 255)
# white_color = (255, 255, 255)

cv2.line(img, pt1, pt2, (0, 0, 255), 5)
cv2.line(img, pt2, pt3, (255, 0, 0), 5)

cv2.imshow('img', img)
cv2.waitKey()
cv2.destroyAllWindows()

 

# rectangle

cv.rectangle(img, pt1, pt2, color[, thickness[, lineType[, shift]]]) -> img

cv.rectangle(img, rec, color[, thickness[, lineType[, shift]]]) -> img

 

Parameters

img	Image.
pt1	Vertex of the rectangle.
pt2	Vertex of the rectangle opposite to pt1 .
color	Rectangle color or brightness (grayscale image).
thickness	Thickness of lines that make up the rectangle. Negative values, like FILLED, mean that the function has to draw a filled rectangle.
lineType	Type of the line.
shift	Number of fractional bits in the point coordinates.

 

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255

pt1 = 0, 0
pt2 = 400, 400

cv2.rectangle(img, pt1, pt2, (0, 255, 0), 5)

cv2.imshow('img', img)
cv2.waitKey()
cv2.destroyAllWindows()

# line + rectangle

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255

pt1 = 0, 0 
pt2 = 500, 0 
pt3 = 0, 500 
pt4 = 30, 30
pt5 = 400, 400

cv2.line(img, pt1, pt2, (0, 0, 255), 5) 
cv2.line(img, pt1, pt3, (255, 0, 0), 5) 
cv2.rectangle(img, pt4, pt5, (0, 255, 0), 3)

cv2.imshow('img', img) 
cv2.waitKey() 
cv2.destroyAllWindows()

 

# clipLine

• 직사각형과 직선이 만나는 교차점을 구하는 함수

cv.clipLine(imgRect, pt1, pt2) ->retval, pt1, pt2

 

Parameters

imgSize	Image size. The image rectangle is Rect(0, 0, imgSize.width, imgSize.height) .
pt1	First line point.
pt2	Second line point.

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255  #흰배경 설정

x1, x2 = 100, 400
y1, y2 = 100, 400
cv2.rectangle(img, (x1, y1), (x2, y2), (0, 255, 0), 3) #사각형 그리기

pt1 = 120, 50
pt2 = 300, 500
cv2.line(img, pt1, pt2, (255, 0, 0), 3) #직선 그리기

imgRect = (x1, y1, x2-x1, y2-y1) 
retval, rpt1, rpt2 = cv2.clipLine(imgRect, pt1, pt2) # 사각형과 직선의 교점구하기
print('retval:', retval)
print('rpt1:', rpt1)
print('rp2:', rpt2)

if retval:  # 접점 그리기
    cv2.circle(img, rpt1, radius= 8, color = (0, 0, 255),thickness=-1)
    cv2.circle(img, rpt2, radius=8, color=(0, 0, 255), thickness=-1)

cv2.imshow('img', img) 
cv2.waitKey() 
cv2.destroyAllWindows()

#retval: True
#rpt1: (140, 100)
#rp2: (260, 399)

 

# circle

cv.circle(img, center, radius, color[, thickness[, lineType[, shift]]]) ->img

 

Parameters

img	Image where the circle is drawn.
center	Center of the circle.
radius	Radius of the circle.
color	Circle color.
thickness	Thickness of the circle outline, if positive. Negative values, like FILLED, mean that a filled circle is to be drawn.
lineType	Type of the circle boundary.
shift	Number of fractional bits in the coordinates of the center and in the radius value.

 

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255 #흰배경 설정

cx = img.shape[0]//2 #배경의 중앙점 설정
cy = img.shape[1]//2

#서로 다른 지름의 원 그리기
cv2.circle(img, (cx, cy), radius=200, color=(0, 0, 255), thickness=2)
cv2.circle(img, (cx, cy), radius=100, color=(0, 255, 0), thickness=2)    
cv2.circle(img, (cx, cy), radius=20, color=(255, 0, 0), thickness=2)    
cv2.circle(img, (cx, cy), radius=1, color=(0, 80, 200), thickness=2)    
    
cv2.imshow('img', img) 
cv2.waitKey() 
cv2.destroyAllWindows()

 

# ellipse

• 타원을 그리는 함수

cv.ellipse(img, center, axes, angle, startAngle, endAngle, color[, thickness[, lineType[, shift]]]) -> img

cv.ellipse(img, box, color[, thickness[, lineType]]) -> img

 

Parameters

img	Image.
center	Center of the ellipse.
axes	Half of the size of the ellipse main axes.
angle	Ellipse rotation angle in degrees.
startAngle	Starting angle of the elliptic arc in degrees.
endAngle	Ending angle of the elliptic arc in degrees.
color	Ellipse color.
thickness	Thickness of the ellipse arc outline, if positive. Otherwise, this indicates that a filled ellipse sector is to be drawn.
lineType	Type of the ellipse boundary.
shift	Number of fractional bits in the coordinates of the center and values of axes.

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255

ptCenter = (img.shape[0] //2, img.shape[1] //2)
size = (200, 100)
cv2.ellipse(img, ptCenter, size, 0, 0, 360,  color=(0, 0, 255))
cv2.ellipse(img, ptCenter, size, 45, 0, 360, color=(0, 255, 0), thickness=1)
cv2.ellipse(img, ptCenter, size, 45, 90, 150, color=(0, 40, 50), thickness=3)
cv2.ellipse(img, ptCenter, size, 20, 0, 360, color=(255, 0, 0), thickness=5) 
    
cv2.imshow('img', img) 
cv2.waitKey() 
cv2.destroyAllWindows()

 

• box 옵션 지정

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255

ptCenter = (img.shape[0] //2, img.shape[1] //2)
size = (200, 100)

box = (ptCenter,size,0)
cv2.ellipse(img, box, (0, 0, 255), 3)
box = (ptCenter,size,45)
cv2.ellipse(img, box, (0, 255, 0), 3)
    
cv2.imshow('img', img) 
cv2.waitKey() 
cv2.destroyAllWindows()

 

# polylines

• 다각형 그리는 함수

cv.polylines(img, pts, isClosed, color[, thickness[, lineType[, shift]]]) ->img

 

Parameters

img	Image.
pts	Array of polygonal curves.
isClosed	Flag indicating whether the drawn polylines are closed or not. If they are closed, the function draws a line from the last vertex of each curve to its first vertex.
color	Polyline color.
thickness	Thickness of the polyline edges.
lineType	Type of the line segments.
shift	Number of fractional bits in the vertex coordinates.

 

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255

pts1 = np.array([[100, 100], [200, 100],[200, 200], [100, 200]])
pts2 = np.array([[400, 100], [300, 200],[400,200]])
cv2.polylines(img, [pts1, pts2], isClosed=True, color=(0, 0, 255), thickness = 2)
pts3 = np.array([[100, 300], [200, 300],[200,400],[100,400]])
cv2.polylines(img, [pts3], isClosed=False, color=(0, 255, 0), thickness = 2)

cv2.imshow('img', img)
cv2.waitKey()
cv2.destroyAllWindows()

 

 

# 도형 혼합

• ellipse + polylines

cv.ellipse2Poly(center, axes, angle, arcStart, arcEnd, delta) ->pts

 

Parameters

center	Center of the arc.
axes	Half of the size of the ellipse main axes.
angle	Rotation angle of the ellipse in degrees.
arcStart	Starting angle of the elliptic arc in degrees.
arcEnd	Ending angle of the elliptic arc in degrees.
delta	Angle between the subsequent polyline vertices. It defines the approximation accuracy.
pts	Output vector of polyline vertices.

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255

ptCenter = (img.shape[0]//2, img.shape[1]//2)
size = (200, 100)

cv2.ellipse(img, ptCenter, size, 0, 0, 360, color=(0, 0, 255))
pts1 = cv2.ellipse2Poly(ptCenter, size, 0, 0, 360, delta=50)
cv2.polylines(img, [pts1], isClosed=True, color=(255, 0, 0))

cv2.ellipse(img, ptCenter, size, 45, 0, 360, color=(0, 255, 0))
pts2 = cv2.ellipse2Poly(ptCenter, size, 45, 0, 360, delta=50)
cv2.polylines(img, [pts2], isClosed=True, color=(255, 0, 0))

cv2.imshow('img', img)
cv2.waitKey()
cv2.destroyAllWindows()

 

• rotated rectangle

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255
ptCenter, size = (img.shape[0]//2, img.shape[1]//2), 200

for angle in range(0, 90, 5):
    rect = (ptCenter, (size, size), angle)
    box = cv2.boxPoints(rect).astype(np.int32)
    r = np.random.randint(256)
    g = np.random.randint(256)
    b = np.random.randint(256)
    cv2.polylines(img, [box], True, (r, g, b), 2)
    
cv2.imshow('img', img)
cv2.waitKey()
cv2.destroyAllWindows()

 

 

 

# fillConvexPoly / fillPoly

• fillConvexPoly : 채워진 블록 다각형을 그리는 함수

cv.fillConvexPoly(img, points, color[, lineType[, shift]]) ->img

 

Parameters

img	Image.
points	Polygon vertices.
color	Polygon color.
lineType	Type of the polygon boundaries.
shift	Number of fractional bits in the vertex coordinates.

 

• fillPoly : 채워진 다각형을 그리는 함수

cv.fillPoly(img, pts, color[, lineType[, shift[, offset]]]) ->img

 

Parameters

img	Image.
pts	Array of polygons where each polygon is represented as an array of points.
color	Polygon color.
lineType	Type of the polygon boundaries.
shift	Number of fractional bits in the vertex coordinates.
offset	Optional offset of all points of the contours.

 

img = np.zeros(shape=(512, 512, 3), dtype=np.uint8) + 255
pts1 = np.array([[100, 100], [200, 100], [200, 200], [100, 200]])
pts2 = np.array([[400, 100], [300, 200], [400,200]])

cv2.fillConvexPoly(img, pts1, (0, 0, 255))
cv2.fillPoly(img, [pts2], (255, 0, 0))

cv2.imshow('img', img)
cv2.waitKey()
cv2.destroyAllWindows()

img1 = np.zeros((400, 400, 3), np.uint8)
img2 = np.zeros((400, 400, 3), np.uint8)

pt1 = np.array([[100, 100], [270, 110], [300, 330], [170, 170], [150,250]],np.int32)
cv2.fillConvexPoly(img1, pt1, (0, 255, 0))
cv2.fillPoly(img2, [pt1], (255, 0, 0))

cv2.imshow('convex', img1)
cv2.imshow('poly', img2)
cv2.waitKey()
cv2.destroyAllWindows()

 

 

 

 

 

• 공식 문서 참고 - https://docs.opencv.org/4.x/d6/d6e/group__imgproc__draw.html