[PYTHON] Affine transformation
Execution environment
Preparing to load images with Google Colaboratory
python
from google.colab import files
from google.colab import drive
drive.mount('/content/drive')
img = cv2.imread("/content/drive/My Drive/Colab Notebooks/img/Lenna.bmp")
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB) #Convert for matplotlib
Loading the required libraries
python
import cv2 #opencv
import matplotlib.pyplot as plt
%matplotlib inline
Flip conversion
python
#Create new window
fig = plt.figure()
#Original image
ax1 = fig.add_subplot(2, 1, 1)
ax1.set_title("Original",fontsize=20)
plt.imshow(img)
#flip upside down= 0
ax2 = fig.add_subplot(2, 3, 4)
ax2.set_title("flipCode = 0",fontsize=20)
plt.imshow(cv2.flip(img,flipCode = 0))
#Up / down / left / right= -1
ax3 = fig.add_subplot(2, 3, 5)
ax3.set_title("flipCode = -1",fontsize=20)
plt.imshow(cv2.flip(img,flipCode = -1))
#Flip horizontal= 1
ax4 = fig.add_subplot(2, 3, 6)
ax4.set_title("flipCode = 1",fontsize=20)
plt.imshow(cv2.flip(img,flipCode = 1))
plt.subplots_adjust(hspace=0.6,wspace=1.2) #Adjust graph spacing.
plt.show()
Flip conversion result
Flip description
cv2.flip(src,flipCode) src = image flipCode = flip direction
| flipcode | direction |
|---|---|
| 0 | Upside down |
| <0 | Up / Down / Left / Right |
| > 0 | Flip left and right |
resize
python
#Create new window
fig = plt.figure()
height = img.shape[0]
width = img.shape[1]
#Original image
ax1 = fig.add_subplot(2, 1, 1)
ax1.set_title("Original",fontsize=20)
plt.imshow(img)
#16×16
ax2 = fig.add_subplot(2, 3, 4)
ax2.set_title("16*16",fontsize=20)
plt.imshow(cv2.resize(img,(16,16)))
#50%
ax3 = fig.add_subplot(2, 3, 5)
ax3.set_title("50%",fontsize=20)
plt.imshow(cv2.resize(img,(int(width*0.5),int(height*0.5))))
#200%*50%
ax3 = fig.add_subplot(2, 3, 6)
ax3.set_title("200%*50%",fontsize=20)
plt.imshow(cv2.resize(img,(int(width*2),int(height*0.5))))
plt.subplots_adjust(hspace=0.6,wspace=1.2) #Adjust graph spacing.
plt.show()
Resize conversion result
rotation
Described at a later date
Perspective projection
Described at a later date
trimming
Described at a later date