Different result after using HoughCircle? [closed]

asked 2017-06-14 03:51:18 -0600

hoang anh tuan
118 ●5 ●8 ●15

I have a video x.

Case 1: Get a frame from the above video. Change frame (color image) to gray image. Then using medianblur. Call HoughCircle and I receive list of circles. Have 3 circles.

Case 2: i save the above frame to jpeg image. Read this image and apply the above functions. I also receive list of circles. But different result about Quantity. I just receive 2 circles.

Why?

thanks

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Closed for the following reason the question is answered, right answer was accepted by hoang anh tuan
close date 2018-05-09 03:32:25.225126

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answered 2017-06-14 06:31:12 -0600

StevenPuttemans

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i save the above frame to jpeg image

This means you are introducing compression, since jpeg is lossy compressing it will have different pixel values when reading the image back from disk. This introduces the different circles found by HoughTransform.

You could try setting the compression to 0 in imwrite, but that would kill the purpose of jpeg images.