Changing UIImage color

Question

I\'m trying to change color of UIImage. My code:

-(UIImage *)coloredImage:(UIImage *)firstImage withColor:(UIColor *)color {
    UIGraphicsBeginImageContext(         


        

Answer 1

Another way to tint an image is to simply multiply it by a constant color. Sometimes, this is preferable because it doesn't "lift" the color values in black areas; it keeps the relative intensities in the image the same. Using an overlay as a tint tends to flatten out the contrast.

This is the code I use:

UIImage *MultiplyImageByConstantColor( UIImage *image, UIColor *color ) {

    CGSize backgroundSize = image.size;
    UIGraphicsBeginImageContext(backgroundSize);

    CGContextRef ctx = UIGraphicsGetCurrentContext();

    CGRect backgroundRect;
    backgroundRect.size = backgroundSize;
    backgroundRect.origin.x = 0;
    backgroundRect.origin.y = 0;

    CGFloat r,g,b,a;
    [color getRed:&r green:&g blue:&b alpha:&a];
    CGContextSetRGBFillColor(ctx, r, g, b, a);
    CGContextFillRect(ctx, backgroundRect);

    CGRect imageRect;
    imageRect.size = image.size;
    imageRect.origin.x = (backgroundSize.width - image.size.width)/2;
    imageRect.origin.y = (backgroundSize.height - image.size.height)/2;

    // Unflip the image
    CGContextTranslateCTM(ctx, 0, backgroundSize.height);
    CGContextScaleCTM(ctx, 1.0, -1.0);

    CGContextSetBlendMode(ctx, kCGBlendModeMultiply);
    CGContextDrawImage(ctx, imageRect, image.CGImage);

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return newImage;
}

Swift version

extension UIImage{

    static func multiplyImageByConstantColor(image:UIImage,color:UIColor)->UIImage{
        let backgroundSize = image.size
        UIGraphicsBeginImageContext(backgroundSize)

        let ctx = UIGraphicsGetCurrentContext()

        var backgroundRect=CGRect()
        backgroundRect.size = backgroundSize
        backgroundRect.origin.x = 0
        backgroundRect.origin.y = 0

        var r:CGFloat
        var g:CGFloat
        var b:CGFloat
        var a:CGFloat
        color.getRed(&r, green: &g, blue: &b, alpha: &a)
        CGContextSetRGBFillColor(ctx, r, g, b, a)
        CGContextFillRect(ctx, backgroundRect)

        var imageRect=CGRect()
        imageRect.size = image.size
        imageRect.origin.x = (backgroundSize.width - image.size.width)/2
        imageRect.origin.y = (backgroundSize.height - image.size.height)/2

        // Unflip the image
        CGContextTranslateCTM(ctx, 0, backgroundSize.height)
        CGContextScaleCTM(ctx, 1.0, -1.0)

        CGContextSetBlendMode(ctx, .Multiply)
        CGContextDrawImage(ctx, imageRect, image.CGImage)

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return newImage
    }
}

Answer 2

Here's my adaptation of @Anna's answer. Two key points here:

• Use destinationIn blending mode
• Call UIGraphicsBeginImageContextWithOptions(backgroundSize, false, UIScreen.main.scale) to get smooth image

Code in in Swift 3:

extension UIImage {

    static func coloredImage(image: UIImage?, color: UIColor) -> UIImage? {

        guard let image = image else {
            return nil
        }

        let backgroundSize = image.size
        UIGraphicsBeginImageContextWithOptions(backgroundSize, false, UIScreen.main.scale)

        let ctx = UIGraphicsGetCurrentContext()!

        var backgroundRect=CGRect()
        backgroundRect.size = backgroundSize
        backgroundRect.origin.x = 0
        backgroundRect.origin.y = 0

        var r:CGFloat = 0
        var g:CGFloat = 0
        var b:CGFloat = 0
        var a:CGFloat = 0
        color.getRed(&r, green: &g, blue: &b, alpha: &a)
        ctx.setFillColor(red: r, green: g, blue: b, alpha: a)
        ctx.fill(backgroundRect)

        var imageRect = CGRect()
        imageRect.size = image.size
        imageRect.origin.x = (backgroundSize.width - image.size.width) / 2
        imageRect.origin.y = (backgroundSize.height - image.size.height) / 2

        // Unflip the image
        ctx.translateBy(x: 0, y: backgroundSize.height)
        ctx.scaleBy(x: 1.0, y: -1.0)

        ctx.setBlendMode(.destinationIn)
        ctx.draw(image.cgImage!, in: imageRect)

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return newImage!
    }
}

Answer 3

Starting from iOS 10 you can use UIGraphicsImageRenderer:

extension UIImage {

    func colored(_ color: UIColor) -> UIImage {
        let renderer = UIGraphicsImageRenderer(size: size)
        return renderer.image { context in
            color.setFill()
            self.draw(at: .zero)
            context.fill(CGRect(x: 0, y: 0, width: size.width, height: size.height), blendMode: .sourceAtop)
        }
    }

}

Answer 4

Anna's code works well for copying a UIImage.image over a colored .image background by using kCGBlendModeNormal rather than kCGBlendModeMultiply. For instance, self.mainImage.image = [self NormalImageByConstantColor: self.mainImage.image withColor: yourColor]; will place the contents of mainImage.image over the tint yourColor while preserving the opacity of yourColor. This solved my problem of placing a background color with opacity behind an image to be saved to the Camera Roll.

Answer 5

For iOS 13 and newer:

let redImage = image.withTintColor(.red, renderingMode: .alwaysTemplate)

Answer 6

In Swift 3.0

imageView.image? = (imageView.image?.withRenderingMode(.alwaysTemplate))!
imageView.tintColor = UIColor.magenta

In Swift 2.0

yourImage.image? = (yourImage.image?.imageWithRenderingMode(.AlwaysTemplate))!
yourImage.tintColor = UIColor.magentaColor()

Enjoy you Swift pioneers