4. OpenCV Image Quality

4.1 Function method: cv2.imwrite('yahboomTest.jpg', img, [cv2.IMWRITE_JPEG_QUALITY, 50])

Parameter meaning:

cv2.CV_IMWRITE_JPEG_QUALITY: Set the image quality of the image format to .jpeg or .jpg, the value is 0---100 (the larger the value, the higher the quality), the default is 95

cv2.CV_IMWRITE_WEBP_QUALITY: Set the image quality of the image format to .webp format, the value is 0--100

cv2.CV_IMWRITE_PNG_COMPRESSION: Set the compression ratio of the .png format, the value is 0--9 (the larger the value, the greater the compression ratio), the default is 3

4.2. Actual effect display

Code path:

/home/pi/project_demo/06.Open_source_cv_fundamentals_course/A.introduction/Introduction_to_OpenCV/04_OpenCV_Img_Quality.ipynb

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import cv2
img = cv2.imread('yahboom.jpg',1)
cv2.imwrite('yahboomTest.jpg', img, [cv2.IMWRITE_JPEG_QUALITY, 50])
#1M 100k 10k 0-100 lossy compression

# 1 lossless 2 transparency attribute
import cv2
img = cv2.imread('yahboom.jpg',1)
cv2.imwrite('yahboomTest.png', img, [cv2.IMWRITE_PNG_COMPRESSION,0]) # jpg 0 high compression ratio 0-100 png 0 low compression ratio 0-9 ``` ``python #bgr8 to jpeg format import enum import cv2 def bgr8_to_jpeg(value, quality=75): return bytes(cv2.imencode('.jpg', value)[1]) ``` ```python import ipywidget s.widgets as widgets image_widget1 = widgets.Image(format='jpg', ) image_widget2 = widgets.Image(format='jpg', ) # create a horizontal box container to place the image widget next to each other image_container = widgets.HBox([image_widget1, image_widget2]) # display the container in this cell's output display(image_container) img1 = cv2.imread('yahboomTest.jpg',1) img2 = cv2.imread('yahboomTest.png',1) image_widget1.value = bgr8_to_jpeg(img1) image_widget2.value = bgr8_to_jpeg(img2) ```` ![](o4.png)