I would like to find photo inside image. Below is an example:
I suppose that first I need to find edges. So I tried 2 approaches: Edge Canny detector:
Adaptive Threshold (with Gaussian smoothing):
As you can see the edges are not perfect. Any ideas how to improve edge detection. Or maybe there is a way to find photo from Canny detector in second image?
Thank you for any tips in advance.
To get the photo-borders: From the canny-edge image compute the 4 longest surrounding lines via HoughLinesP and then compute the intersection points.
In this nice tutorial it is explained in more detail: http://opencv-code.com/tutorials/automatic-perspective-correction-for-quadrilateral-objects/
Thanks. This tutorial looks great. The problem is that in the tutorial Canny detector provides very clean edges. While in my case (second image) I have lots of noise. That's probably because the quality of my image is lower. Is there a way to improve quality of image to get better edges?
Typically you denoise your image (e.g. with Non-Local-Means, see http://docs.opencv.org/modules/photo/doc/denoising.html?highlight=fastnlmean#fastnlmeansdenoisingcolored). Furthermore, before you run Canny you also smooth the image with a small Gaussian (sigma~2). However, I think you won't need these two steps, since when using HoughLinesP you can say that your lines can have gaps and that it has to have a certain length, which makes it pretty much prone to image noise.
It all depends on what he actually wants :) Else solution of @Guanta will be exactly what he is looking for.
Asked: 2013-06-04 07:52:15 -0600
Seen: 1,082 times
Last updated: Jun 04 '13
It's not clear what you actually want to do. Do you want to find this specific photo or do you want to rotate and crop a scanned image to extract all kinds of scanned photos?
I have same images with single (internal) photo. The photos inside images are different and they are on different background. But there is only single photo on every image. I want to crop the image to the internal photo.