[{"id":4658,"name":"4.OpenCV image quality","moduletypeid":782,"content":"

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OpenCV image quality<\/span><\/strong><\/span><\/p>

Code path:<\/span><\/em><\/span><\/p>

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\/home\/pi\/Yahboom_Project\/Raspbot\/1.OpenCV_course\/01Getting_started\/OpenCV\/03_OpenCV_image_quality.ipynb<\/span><\/em><\/span><\/p>

1) Compression method<\/span><\/p>

cv2.imwrite('yahboomTest.jpg', img, [cv2.IMWRITE_JPEG_QUALITY, 50])<\/span><\/p>

cv2.CV_IMWRITE_JPEG_QUALITY<\/span>: Set the picture(.jpeg or .jpg) quality, value range is 0--100 (the larger the value, the higher the quality). Default value is 95<\/span><\/span><\/p>

cv2.CV_IMWRITE_WEBP_QUALITY<\/span>: Set the picture(.web) quality, value range is 0--100 (the larger the value, the higher the quality). <\/span><\/span><\/p>

cv2.CV_IMWRITE_PNG_COMPRESSION<\/span>: Set the picture(.png) quality, value range is 0--100 (the larger the value, the higher Compression ratio). Default value is 3.<\/span><\/span><\/p>

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import cv2img = cv2.imread('yahboom.jpg',1)cv2.imwrite('yahboomTest.jpg', img, [cv2.IMWRITE_JPEG_QUALITY, 50])#1M 100k 10k 0-100 Lossy compression<\/span><\/p><\/pre><\/td><\/tr><\/tbody><\/table>
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# 1 Lossy compression, 2 Transparency attributeimport cv2img = 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<\/span><\/p><\/pre><\/td><\/tr><\/tbody><\/table>
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#bgr8 to jpeg formatimport enumimport cv2 def bgr8_to_jpeg(value, quality=75):return bytes(cv2.imencode('.jpg', value)[1])<\/span><\/p><\/pre><\/td><\/tr><\/tbody><\/table>
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import ipywidgets.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 eachotherimage_container = widgets.HBox([image_widget1, image_widget2]) # display the container in this cell's outputdisplay(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)<\/span><\/p><\/pre><\/td><\/tr><\/tbody><\/table>
 \"image.png\"\/<\/span><\/span><\/p>
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