How to use GPUImageMaskFilter with camera input

Question

I'm using BradLarson's GPUImage iOS framework. I'm trying to add a mask to my live camera input following the example in the filtershowcase. With other filters this simple chain works but with GPUImageMaskFilter it doesn't. My output is just a white screen. What's missing?

This is my code:

    stillCamera = [[GPUImageStillCamera alloc] init];
    stillCamera.outputImageOrientation = UIInterfaceOrientationPortrait;

    GPUImageView *filterView = [[GPUImageView alloc]initWithFrame:CGRectMake(0, 0, 320, 427)];
    [self.view addSubview:filterView];

    maskFilter = [[GPUImageMaskFilter alloc] init];
    [(GPUImageFilter*)maskFilter setBackgroundColorRed:0.0 green:1.0 blue:0.0 alpha:1.0];
    UIImage *mask = [UIImage imageNamed:@"mask.png"];
    GPUImagePicture *maskImage = [[GPUImagePicture alloc] initWithImage:mask smoothlyScaleOutput:YES];
    [maskImage processImage];
    [maskImage addTarget:maskFilter];

    [stillCamera addTarget:maskFilter];
    [maskFilter addTarget:filterView];

    [stillCamera startCameraCapture];

I also tried with the GPUImageVideoCamera but that doesn't help. I think the problem might be with the filter chain or the declaration of the mask filter.

I checked this question How to Implement GPUImageMaskFilter using GPUImage but this is for still pictures and not live camera input.

Any ideas?

Answer 1

You need to first add targets like :

[stillCamera addTarget:maskFilter];
[maskImage addTarget:maskFilter];

then process the image :

[maskImage processImage];

then you can pass the filter result to the view :

[maskFilter addTarget:filterView];