Question

how i apply CIToneCurve filter i applied

  filter= [CIFilter filterWithName:@"CIScreenBlendMode"];
     [filter setValue:beginImage1 forKey:kCIInputImageKey];
     [filter setValue:beginImage forKey:@"inputBackgroundImage"];

different filters with this approach now i want to apply CIToneCurve how should i apply this with these parameters

inputImage
A CIImage class whose display name is Image.

inputPoint0
A CIVector class whose attribute type is CIAttributeTypeOffset and whose display name is Point 1. Default value: [0, 0] Identity: [0, 0]

inputPoint1
A CIVector class whose attribute type is CIAttributeTypeOffset and whose display name is Point 2l. Default value: [0.25, 0.25] Identity: [0.25, 0.25]

inputPoint2
A CIVector class whose attribute type is CIAttributeTypeOffset and whose display name is Point 3l. Default value: [0.5, 0.5] Identity: [0.5, 0.5]

inputPoint3
A CIVector class whose attribute type is CIAttributeTypeOffset and whose display name is Point 4. Default value: [0.75, 0.75] Identity: [0.75, 0.75]

inputPoint4
A CIVector class whose attribute type is CIAttributeTypeOffset and whose display name is Point 5. Default value: [1, 1] Identity: [1, 1]

i write these but my app crash with out giving any error

Answer 1

each filter accepts different kind of parameters but once you get use to them is pretty easy.
You didn’t post what error you are getting but this works for me:

- (void)doCIToneCurveFilter
{
    // Set an appropriate image. A bit dark so we see the results clearer
    // This image is being taken from http://photo.tutsplus.com/tutorials/post-processing/adobe-camera-raw-for-beginners-tone-curve/
    imageView.image = [UIImage imageNamed:@"turtles"];
    imageView.frame = CGRectMake(0, 0, imageView.image.size.width*0.7, imageView.image.size.height*0.7); // shrank this a bit 2 images fit on screen

    // Make the input image recipe
    CIImage *inputImage = [CIImage imageWithCGImage:imageView.image.CGImage];

    // Make tone filter filter
    // See mentioned link for visual reference
    CIFilter *toneCurveFilter = [CIFilter filterWithName:@"CIToneCurve"];
    [toneCurveFilter setDefaults];
    [toneCurveFilter setValue:inputImage forKey:kCIInputImageKey];
    [toneCurveFilter setValue:[CIVector vectorWithX:0.0  Y:0.0] forKey:@"inputPoint0"]; // default
    [toneCurveFilter setValue:[CIVector vectorWithX:0.27 Y:0.26] forKey:@"inputPoint1"]; 
    [toneCurveFilter setValue:[CIVector vectorWithX:0.5  Y:0.80] forKey:@"inputPoint2"];
    [toneCurveFilter setValue:[CIVector vectorWithX:0.7  Y:1.0] forKey:@"inputPoint3"];
    [toneCurveFilter setValue:[CIVector vectorWithX:1.0  Y:1.0] forKey:@"inputPoint4"]; // default

    // Get the output image recipe
    CIImage *outputImage = [toneCurveFilter outputImage];

    // Create the context and instruct CoreImage to draw the output image recipe into a CGImage
    CIContext *context = [CIContext contextWithOptions:nil];
    CGImageRef cgimg = [context createCGImage:outputImage fromRect:[outputImage extent]];

    // Draw the image in screen
    UIImageView *imageView2 = [[UIImageView alloc] initWithImage:[UIImage imageWithCGImage:cgimg]];
    CGRect f = imageView2.frame;
    f.origin.y = CGRectGetMaxY(imageView.frame);
    f.size.width = imageView.frame.size.width;
    f.size.height = imageView.frame.size.height;
    imageView2.frame = f;

    [self.view addSubview:imageView2];
}

And this is the result:

The image I used was taken from here and there you can find the curve I approximated in this example:

PS: If you are wondering why the my result image does not look exactly the same as the result in the link it is because my image is a partial image and color distribution is different. Alike but not exactly the same. So applying exactly the same curve will not give the exactly same result.

I hope it helps