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Reconstruct stitched image

asked 2015-10-20 01:00:02 -0500

alexandra gravatar image

updated 2015-10-20 04:26:46 -0500

berak gravatar image


I used OpencCV stitching class to stitch these images, but the result contain black area. I don't want to crop the image to remove the black area because some image details will be missed. Is there any way ( function or algorithm) to reconstruct the image so that the black area will be filled with appropriate pixels ??

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inpaint() might be helpful

berak gravatar imageberak ( 2015-10-20 01:41:23 -0500 )edit

Thanks, i will try it.

alexandra gravatar imagealexandra ( 2015-10-20 02:49:00 -0500 )edit

how can i paint just the black area around my image??

alexandra gravatar imagealexandra ( 2015-10-20 03:42:45 -0500 )edit

You do a mask of the black area (I suppose that everything is 0 there); see threshold, or maybe floodfill with seeds from the 4 corners of the stitched image

thdrksdfthmn gravatar imagethdrksdfthmn ( 2015-10-20 03:56:26 -0500 )edit

you mean the mask ?

Mat gray; cvtColor(img, gray, COLOR_BGR2GRAY);
// find black region:
Mat mask = (gray == 0); // mask is 'on', where gray is black
berak gravatar imageberak ( 2015-10-20 04:05:33 -0500 )edit

I test this example link text its work fine but i want it to paint the black area without using the white painting ??

alexandra gravatar imagealexandra ( 2015-10-20 04:29:14 -0500 )edit

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answered 2015-10-20 04:22:59 -0500

berak gravatar image

updated 2015-10-20 04:26:29 -0500

i would try to use inpaint

( not on the whole image, but only the border regions ):

void doInpaint(Mat &img)
    // find black region:
    Mat gray; cvtColor(img,gray,COLOR_BGR2GRAY);
    Mat mask = gray == 0;

    // pre-fill  black areas with mean color,
    // for easier interpolation
    Scalar m,s;
    cv::meanStdDev(img, m, s, ~mask); // inverted mask !
    img.setTo(m, mask);


void main()
    int S = 30;
    Mat img = imread("stich_inp.png");
    // top
    // bottom
    // left
    // right
    imshow("final", img);
    imwrite("final.png", img);

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@berak You can also create the mask based on the channel 0, no? But the result is ugly... isn't it better to cut the black part so you'll have a little smaller image?

thdrksdfthmn gravatar imagethdrksdfthmn ( 2015-10-20 05:06:39 -0500 )edit

@thdrksdfthmn ,

  • "You can also create the mask based on the channel 0" - that would only give you "not blue" , imho better from grayscale.

  • "isn't it better to cut the black part so you'll have a little smaller image" - that would have been my 1st idea, too, but she kinda wanted to avoid that explicitly, no ?

berak gravatar imageberak ( 2015-10-20 05:18:38 -0500 )edit

@berak thank you so much, but when i tested on another image the result is not good, there is a big different in color and its not the same as the example in the link i mentioned above. Why you are using s=30 ??

alexandra gravatar imagealexandra ( 2015-10-20 05:50:23 -0500 )edit
  • "Why you are using s=30 " S=30 -> size of the border strip to process (you don't want to inpaint the whole image, just the top/bottom/left/right strip)

  • "i tested on another image the result is not good," - ah, shame. maybe add that to your question ?

berak gravatar imageberak ( 2015-10-20 06:08:47 -0500 )edit

mask is 1-channel 8-bit, while src is 1 or 3 channels, so I suppose it is doing the inpainting on all the channels...

thdrksdfthmn gravatar imagethdrksdfthmn ( 2015-10-20 06:16:37 -0500 )edit
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Asked: 2015-10-20 01:00:02 -0500

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Last updated: Oct 20 '15