Rotate Image segment without background

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Malan Jayanka 2016-9-16

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https://ww2.mathworks.cn/matlabcentral/answers/303260-rotate-image-segment-without-background

评论： Image Analyst 2018-2-10

采纳的回答： Gopichandh Danala

I want to rotate image like this

I have rotated Image but I have got image like this in matlab

How to fix this problem in matlab Actually I want only rotate leaf part only not whole image. Is it posibble

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Gopichandh Danala 2016-9-16

Thanks image analyst i will do as u suggested from now..

Malan Jayanka 2016-9-18

Gopichandh Danala, Thank you for your answer. But I have a problem. When the whole image was rotated, that image was rotated and leaf part became small. But here I want to maintain the leaf size as same as the original image. Is this possible in matlab?

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Gopichandh Danala 2016-9-16

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在 MATLAB Online 中打开

A simple trick is to change all the pixels other than the segment to a white background in your case.

I cropped your main image as u didn't post original image

and sample code is here:

leaf = imread('leaf.jpg');
figure, imshow(leaf, []);
rotateImg = imrotate(leaf,45,'crop'); % rotate by 45 or 315 degrees
figure, %imshow(rotateImg);
subplot(1,2,1)
imshow(rotateImg, [min(min(rotateImg(:))) max(max(rotateImg(:)))]);
newrotateImg = rotateImg;
newrotateImg(newrotateImg == 0) = 255; % make all 0 pixels to 255..
subplot(1,2,2)
imshow(newrotateImg, [min(min(newrotateImg(:))) max(max(newrotateImg(:)))]);

Hope it helps.

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Image Analyst 2016-9-18

编辑：Image Analyst 2016-9-18

Setting black to white won't be totally robust either. What if the stem has black in it? What if the leaf has black in it? What if the stem touches the border, so that setting only black touching the border to white is changed? That would also set the stem to white. You need to define parameters. For example, it appears that the background can now be blue instead of white, and it can have a gradient in color across the image. That will have to be taken into account. You could just find the mean color of the background and set the corner triangles to that color, but you'll have noticeable triangles in the corner because the color won't match the edges everywhere. But it's a good start.

You hopefully looked at my other leaf code in other posts. I'd probably convert to HSV color space and segment out the green by thresholding the saturation, and possibly the hue channel. Then you might need to combine it with a threshold on the V channel to get the dark brown stem. Then combine the two binary images to get a mask of the leaf and stem together. You might have to call imfill() to get rid of any internal holes in the binary image. Then get the mean RGB color of the non-leaf mask so you can fill in the triangles.

So there's a bit more to it if you want to be robust for all kinds of leaves with different colors. Ideally you'd have control over the lighting and snap a background picture. Even better, have an x-rite Color Checker chart in each photo to do color correction on it. You'll need to call functions like imfill(), imclearborder(), bwareafilt(), mean(), etc. A robust program is not going to be some simple 20 line program.

One question, it looks like you're removing the background. Do you want to keep the blue/white shaded background, or just mask it out and make it all white?

Perhaps Gopichandh Danala will do all that for you, and I don't want to jump in if he's going to do it since you asked him specifically. If not, you could open up your question to others.