Opencv read image when camera is refocus (still blur)

Question

I have a python program which uses opencv VideoCapture to capture webcam image (in my case logitech c922). It has autofocus feature which is great but I don't know when the refocus is done and that makes the image that I capture blurred (not focus yet)

Is there any way to know when the camera already focusses?

You should probably search for a library which could interact with this specific camera, Only that library can give you a finer control as to what camera hardware is doing, OpenCV has no such functionality to extract the data from the camera. — ZdaR, Aug 08 '18 at 05:38

score 1 · Answer 1 · answered Aug 08 '18 at 05:48

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Besides interacting with camera hardware that @ZdaR has mentioned, you can determine whether the image is sharp or not every frame. If the image is sharp, most probably the camera is in focus.

There are some great answers here on determining the sharpness of an image.

In the case of having a depth-of-view (the object is sharp while the background is blurry), you can set the threshold on some of the sharpest pixels only (i.e. sharpest 20% pixels). Since a out-of-focus or focusing image should be blurry altogether.

answered Aug 08 '18 at 05:48

hkchengrex

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i already tried it. but if the image is to sparse its return as blur. – Muhammad Salman Galileo Aug 08 '18 at 05:53
@MuhammadSalmanGalileo What do you mean by sparse? It would be great if you can add that (that you have tried this method and the result that you get) in your question too so that others can help. – hkchengrex Aug 08 '18 at 05:55
if i tried to do that to white only image (sparse), its return 0. its also happend when the image is mostly the same thing like flat wall (its return small number). i use this example https://www.pyimagesearch.com/2015/09/07/blur-detection-with-opencv/ – Muhammad Salman Galileo Aug 08 '18 at 06:13

score 0 · Answer 2 · answered Aug 08 '18 at 05:52

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You can set the focus manually so that the camera is focused already when you need to use the camera.

Here is the code:

cap.set(3, 1280) # set the resolution
cap.set(4, 720)
cap.set(cv2.CAP_PROP_AUTOFOCUS, 0)

answered Aug 08 '18 at 05:52

hypadr1v3

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many thanks for the answer. but i really need the autofocus, because i use this program for automation. – Muhammad Salman Galileo Aug 08 '18 at 06:16
can you please specify what exactly are you doing so I can find the best solution for it? – hypadr1v3 Aug 08 '18 at 06:25
i make something like image 2D image scanning with moving paper in zigzag manner so i can capture higher resolution image after processing it with image stitching. but i need the autofocus because it seem out of focus in certain position – Muhammad Salman Galileo Aug 08 '18 at 06:48
If it's like that then I think that this is not a problem with programming but a problem with your camera. Try another camera and tell me the results – hypadr1v3 Aug 08 '18 at 06:56
cap is your webcam – hypadr1v3 Jan 15 '20 at 13:22

Opencv read image when camera is refocus (still blur)

2 Answers2