Change brightness, contrast and saturation using sliders

[cacdzya]

Hi. I'm trying to change brightness, contrast and saturation together to implement using sliders; the code works for me in some images, but in other images my app crashes. When I applied this part of the code:

[filtroSaturacion useNextFrameForImageCapture];
[stillImageSource processImage];

I hope you can help me and thanks four your help. Here I leave my code:

• (void) inicializarBasicos {

  gpuViewImagen = [[GPUImageView alloc] initWithFrame:copiaViewImagen.frame];

  stillImageSource = [[GPUImagePicture alloc] initWithImage:copiaViewImagen.image];

  filtroBrillo = [[GPUImageBrightnessFilter alloc] init];
  filtroContraste = [[GPUImageContrastFilter alloc] init];
  filtroSaturacion = [[GPUImageSaturationFilter alloc] init];

  [filtroBrillo forceProcessingAtSize:copiaViewImagen.image.size];
  [filtroContraste forceProcessingAtSize:copiaViewImagen.image.size];
  [filtroSaturacion forceProcessingAtSize:copiaViewImagen.image.size];

  [stillImageSource addTarget:filtroBrillo];

  [filtroBrillo addTarget:filtroContraste];
  [filtroContraste addTarget:filtroSaturacion];
  [filtroSaturacion addTarget:gpuViewImagen];

  [_view_total addSubview:gpuViewImagen];

  [_view_total sendSubviewToBack:gpuViewImagen];
  }

• (IBAction)sliderValueChangedBrillo:(id)sender {

  [filtroSaturacion removeAllTargets];

  [filtroBrillo setBrightness:_slider_brillo.value];

  [filtroSaturacion useNextFrameForImageCapture];

  [stillImageSource processImage];

  UIImage *nearestNeighborImage = [filtroSaturacion imageFromCurrentFramebuffer];

  viewImagenSeleccionada.image = nearestNeighborImage;

  _boton_restaurar_foto.userInteractionEnabled = YES;
  }

• (IBAction)sliderValueChangedContraste:(id)sender {

  [filtroContraste setContrast:_slider_contraste.value];

  [filtroSaturacion useNextFrameForImageCapture];

  [stillImageSource processImage];

  UIImage *nearestNeighborImage = [filtroSaturacion imageFromCurrentFramebuffer];

  viewImagenSeleccionada.image = nearestNeighborImage;

  _boton_restaurar_foto.userInteractionEnabled = YES;
  }

• (IBAction)sliderValueChangedSaturacion:(id)sender {

  [filtroSaturacion setSaturation:_slider_saturacion.value];

  [filtroSaturacion useNextFrameForImageCapture];

  [stillImageSource processImage];

  UIImage *nearestNeighborImage = [filtroSaturacion imageFromCurrentFramebuffer];

  viewImagenSeleccionada.image = nearestNeighborImage;

  _boton_restaurar_foto.userInteractionEnabled = YES;
  }