Core Image provides a mechanism for filtering and manipulating images and videos. Think Instagram filter effects.

Example filters

• cropping
• color effects
• blurring
• warping
• transformations
• gradients

Take a CIImage and apply CIFilter to draw on CIContext

Example

// 1. Get a CIImage
CIImage *image = [CIImage imageWithContentsOfURL:myURL];

// 2. Create a CIFilter
CIFilter *filter = [CIFilter filterWithName:@"CISepiaTone"];

// 3. Apply the filter to the image
[filter setValue:image forKey:kCIInputImageKey];

// 4. More CIFilter customization
[filter setValue:[NSNumber numberWithFloat:0.8f] forKey:@"InputIntensity"];

// 5. Get the resulting image from CIFilter
CIImage *result = [filter valueForKey:kCIOutputImageKey];

// 6. Create CIContext
CIContext *context = [CIContext contextWithOptions:nil];

// 7. Finally, render CIImage onto Core Graphics Image, which then can be displayed or saved.
CGImageRef cgImage = [context createCGImage:result fromRect:[result extent];

// 8. Convert CGImage to UIImage, so we can draw it onto view
UIImage *resultUIImage = [UIImage imageWithCGImage: cgImage];

// 9. Get the CGRect to draw on
CGRect imageRect =[[UIScreen mainScreen] bounds];

// 10. Draw the UIImage onto the CGRect region
[resultUIImage drawInRect:imageRect];