How to detect the boundary of an uiimage

Question

In my application i want to detect the boundaries of an uiimage. I'm having an flower image has many parts like,(lief,sticky bulb etc..)as a single image.If i'm touch the particular lief means it find the boundary value of that particular lief and return the value.

I'm having no idea about this.Please any one help me out to do this.

are you placeing the image in an UIImageView? what exactly you mean by boundry? the frame? — jithinroy, Feb 02 '11 at 09:56
@xCode:yes,i'm having an image in uiimageview.boundary in the sense,part of that image(flower)like..,lief — kanmani, Feb 02 '11 at 10:31

score 2 · Answer 1 · answered Oct 03 '13 at 14:46

2

You can use "Flood Fill Algorithm" for that.

Only getting the touch points is not sufficient for this answer.

You need to break all in pixels and then you will use that further.

answered Oct 03 '13 at 14:46

virantporwal

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score 0 · Answer 2 · answered Feb 02 '11 at 10:00

You could implement some edge detecion algorithm. But unless you have some experience in image processing I think that would be a major headache.

If you have the image in advance (do you?) you could separate the image as a composition of masks and detect the touches in the corresponding mask. The idea is that for each part of the image you will have a corresponding bitmap mask. When you receive a touch, you check all masks to see which one has a black pixel in the location of the touch. It is a thick Quartz technique, but I think it is much more approachable than the edge detection. Check out the relevant quartz documentation.

score -1 · Answer 3 · answered Feb 02 '11 at 11:34

I think you can do this by subclassing the UIImageView and detecting the touchevent and position.

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {  
    UITouch *touch = [touches anyObject];   
    CGPoint position = [touch locationInView:self];      
}

I havent tried this, but seems like this will solve your problem.

How to detect the boundary of an uiimage

3 Answers3