I'm building an iphone photo app. I don't know how to achieve this kind of effect on an image:
When the user drags a finger across the arrow, I want the image to be distorted accordingly. How can I achieve this? Is there any framework that makes this process simple?
Thank you.
No clue about iOS, but the look reminds me of a thin-plate spline warp. It's quite easy to implement in OpenGL, a quick Google search for example code returns plenty of hits.
From the sound of it I think your looking for the CoreImage framework. Look into the various distortion effects...in particular CIBumpDistortionLinear.
I don't have any code so check out this tutorial and read up on CoreImage.
Related
I am using AVFoundation to take pictures instead of UIImagePicker due to how customizable the user interface presented to the user can be. When using it the aspect ratio that the picture is saved as is the same as the iPhone's video feed. What I want to happen is to have the pictures saved in the same aspect ratio as normal pictures are.
The way that I am currently approaching this is to overlay a black bar in the excess preview display and then just crop the photo after saving it as an image.
However, this feels very crude. I assume that it is a common thing to use the AVFoundation as a way of taking photos and so I assume I must be missing something!
I have used this example code. And I have read through the AVFoundation documentation but can only assume that I am missing a function. I have also read through similar questions to this which describe the process by which I might go about cropping images, but that isn't really my concern.
On the other hand, if there is no standard way to do this, please do let me know so that I can stop worrying that I am approaching it in a convoluted way.
Also, I am using Objective-C so if answers contain code, please could you use the same language?
I want to create a area of similar colors when user touches into a point on imageview. Who knows library or technique to resolve problems for ios.
Original image link:
http://cannshine.com/images/1.jpg
After touched by user, link:
http://cannshine.com/images/2.jpg
Please helping, thanks!
It looks to me like you want to create a magic wand tool, correct? I can't help you come up with a way to handle this and I don't know of any libraries that can select a group of like-colored pixels based on tolerance, but there is this article here I found. It covers implementing a magic wand tool using Objective-C. I found it in the answer to this similar question on SO.
I'm following this guide: http://www.aishack.in/2010/08/sudoku-grabber-with-opencv/2/
and modifying to iOS 5.0.
I managed to find the largest contour (the sudoku "board"), however, it only locates the surrounding square, without the lines inside, as in the tutorial. can this be easily solved?
I'll try and find a way around it, but still would like to know. thanks!
I assume that you are using the camera right now. Try to load the image what is used in the tutorial and check if your implementation works on that image. Then you can continue with nice sudoku images from the web. You may also change the camera angle and distance from the sudoku when taking pictures to get a better, clearer view.
I am trying to develop an iphone application which needs to show a 360 degree video like the one and rotate the video as per the phone movement. How can i do this? Is it possible to do this with normal MPMovieplayer controller?
I don't think you can do this with a normal MPMoviePlayerController, but there are several libraries out there to achieve this. Have a look here:
PanoramaGL
Panorama 360
They work with OpenGL and you can embed them in your Objective-C code.
EDIT:
As #Mangesh Vyas kindly pointed out those are intended to use with fixed images only. However they might be a suitable starting point for embedding video as well, if you modify the code accordingly. They already do the handling of direction, accelerometer etc. so you don't have to implement all that yourself.
I'm basically trying to work out how to take a slice of an image, say a screenshot of an iPhone home screen, slice out the first icon and compare it to a set array of images in a library. Any help on where to start?
I'm no iPhone programmer, but I might be able to suggest a few things:
The SURF feature detection implemented in OpenCV should help you with this
There is a nice article on using OpenCV in Objective-C code.
A quick & dirty way might be to use the difference blend mode which should return the difference between the 1st image(top) and the 2nd image(bottom). If there is no difference the result will be completely black. So, the more black pixels in the difference result, potentially, the more similarities between the compared images.
I'm not an iOS developer, so I don't know if there is an image library that ships with sdk or if there's a free/opensource library for basic image processing. Still this should be trivial to implement:
e.g.
- (int)difference((int)topPixel,(int)bottomPixel)
{
return abs(topPixel-bottomPixel);
}
Note: Syntax might not be correct :)
HTH
This may not help you with taking a screenshot of the iOS home screen... But these articles show how to take snapshots from within a UIKit application:
https://developer.apple.com/library/prerelease/ios/#qa/qa1703/_index.html
https://developer.apple.com/library/prerelease/ios/#qa/qa1714/_index.html
Perhaps you would instruct the user to press home-power (buttons) to take a snapshot and store in the photo roll, then load that screenshot into an app to process the screenshot.
Hope this helps!