GPUImage 库的 GPUImagePicture 中不支持 alpha

使用了 GPUImage

代码如下

- (void)setupDisplayFiltering;
{
    UIImage *inputImage = [UIImage imageNamed:@"grossini.png"]; // The WID.jpg example is greater than 2048 pixels tall, so it fails on older devices
    
    sourcePicture = [[GPUImagePicture alloc] initWithImage:inputImage smoothlyScaleOutput:YES];    
    GPUImageView *imageView = (GPUImageView *)self.view;

    [sourcePicture addTarget:imageView];
    [sourcePicture processImage];
}