Get a pixel color from GPUImageVideoCamera

Question

I've created a simple green screen with GPUImage library and the following code:

import UIKit
import GPUImage


class CaptureViewController: UIViewController {

  var videoCamera:GPUImageVideoCamera?
  var filter:GPUImageChromaKeyFilter?

@IBOutlet weak var cameraView: GPUImageView!

override func viewDidLoad() {
    super.viewDidLoad()
    cameraView.backgroundColor = UIColor.clearColor()
    videoCamera = GPUImageVideoCamera(sessionPreset: AVCaptureSessionPreset640x480, cameraPosition: .Back)
    videoCamera!.outputImageOrientation = .Portrait;
    filter = GPUImageChromaKeyFilter()
    filter?.setColorToReplaceRed(0.0, green: 1.0, blue: 0.0)
    filter?.thresholdSensitivity = 0.4
    videoCamera?.addTarget(filter)
    filter?.addTarget(cameraView)
    videoCamera?.startCameraCapture()
}

override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)
}
}

Now I want to change the color from green to where ever the user taps on the video.

Q: How can I get the pixel data from the tapped location?

Did you show us in application ruuning mood how many portion you want a green that your tap on screen ? and did you put a tap gesture in videocamera ? — Himanshu Moradiya, Oct 18 '16 at 05:18
@AndyFedoroff right now i dont have code but i give you one idea that throw you can solve this problem and you can get correct coordinate of your tap — Himanshu Moradiya, Oct 18 '16 at 13:12
@AndyFedoroff create one programmatically view and add it into your camera video view and add one selector method of tap gaesture in that programically view and on method to access your tap geasture co ordinates and create one view that you need like 9*9 block . so your problem will be solve . — Himanshu Moradiya, Oct 18 '16 at 13:21

score 2 · Answer 1 · answered Oct 19 '16 at 23:01

Is your question how do you get the touch point in the view (override touchesEnded and look at touch.locationInView) or how do you read back the pixel values at or around that point?

The answer to the latter is that he GPUImage project has an example called RawDataTest that shows you how to read the RGBA values for arbitrary pixels in a view from the GPU.

https://github.com/BradLarson/GPUImage/tree/master/examples/iOS/RawDataTest/RawDataTest

Get a pixel color from GPUImageVideoCamera

1 Answers1