Objective c image set size is not distorted

Question

When i blend 2 image width GPUImage 2 image auto fix same size main image. But main image size horizontal or vertical top image distorted.
I try using image vector, set new size and using nine-patch but new image frame not different.you have answer can help me.

Thank!

this is my code

-(UIImage*)imageBlendFrameDefault:(UIImage *)blenFrame{
    GPUImagePicture *mainPicture = [[GPUImagePicture alloc] initWithImage:_inputImage];
    GPUImagePicture *topPicture = [[GPUImagePicture alloc] initWithImage:blenFrame];

    GPUImageAlphaBlendFilter *blendFilter = [[GPUImageAlphaBlendFilter alloc] init];

    [blendFilter setMix:0.8];

    [mainPicture addTarget:blendFilter];
    [topPicture addTarget:blendFilter];


    [mainPicture processImage];
    [topPicture processImage];

    [blendFilter useNextFrameForImageCapture];

    UIImage * mergedImage = [blendFilter imageFromCurrentFramebuffer];
    return mergedImage;
}

Answer 1

cut frame using UIGraphicsBeginImageContextWithOptions