用编程的方式更改uiimage色调

首先，你需要决定，如果你正在一个固定的色调图像，还是旋转现有的色调

Fixed  hue 固定色调

固定的色调，可以使用标准的绘图工具-只需要确保的混合模式设置kCGBlendModeHue ，合适的色调与绘制。

这是来自尼蒂什的解决方案，但我发现， saturation小于1.0有不一致的结果。
这种方法是允许不同的字母，但真正的饱和度超过100％，你可能会需要第二轮的绘图

 - (UIImage*) imageWithImage:(UIImage*) source fixedHue:(CGFloat) hue alpha:(CGFloat) alpha; // Note: the hue input ranges from 0.0 to 1.0, both red. Values outside this range will be clamped to 0.0 or 1.0.

{ // Find the image dimensions. CGSize imageSize = [source size];

CGRect imageExtent = CGRectMake(0,0,imageSize.width,imageSize.height);

// Create a context containing the image. UIGraphicsBeginImageContext(imageSize);

CGContextRef context = UIGraphicsGetCurrentContext();

[source drawAtPoint:CGPointMake(0,0)];

// Draw the hue on top of the image.

CGContextSetBlendMode(context, kCGBlendModeHue);

[[UIColor colorWithHue:hue saturation:1.0 brightness:1 alpha:alpha] set];

UIBezierPath *imagePath = [UIBezierPath bezierPathWithRect:imageExtent];

[imagePath fill];

// Retrieve the new image.

UIImage *result = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return result; }

Rotated hue旋转色调

要旋转的色调，你需要的Core Image过滤器

下面的代码转换的UIImage到一个CIImage，然后将结果转换的​​UIImage显示。

根据您的图片来自，您可能能够避免这些步骤中的一个或两个

.方便的是，第一个例子中的的核心图像编程指南：核心的图像过滤器使用的CIHueAdjust的过滤器。

// #import <CoreImage/CoreImage.h>

- (UIImage*) imageWithImage:(UIImage*) source rotatedByHue:(CGFloat) deltaHueRadians;

{ // Create a Core Image version of the image.

CIImage *sourceCore = [CIImage imageWithCGImage:[source CGImage]];

// Apply a CIHueAdjust filter CIFilter *hueAdjust = [CIFilter filterWithName:@"CIHueAdjust"];

[hueAdjust setDefaults]; [hueAdjust setValue: sourceCore forKey: @"inputImage"];

[hueAdjust setValue: [NSNumber numberWithFloat: deltaHueRadians] forKey: @"inputAngle"];

CIImage *resultCore = [hueAdjust valueForKey: @"outputImage"];

// Convert the filter output back into a UIImage. /

/ This section from http://stackoverflow.com/a/7797578/1318452

CIContext *context = [CIContext contextWithOptions:nil];

CGImageRef resultRef = [context createCGImage:resultCore fromRect:[resultCore extent]];

UIImage *result = [UIImage imageWithCGImage:resultRef];

CGImageRelease(resultRef);

return result; }

 

 

2

- (void) changeToHue:(float)hue saturation:(float)saturation

{ UIGraphicsBeginImageContext(self.bounds.size);

CGContextRef context = UIGraphicsGetCurrentContext();

UIView *hueBlend = [[UIView alloc] initWithFrame:self.bounds];

hueBlend.backgroundColor = [UIColor colorWithHue:hue saturation:saturation brightness:1 alpha:1];

CGContextDrawImage(context, self.bounds, self.image.CGImage);

CGContextSetBlendMode(context, kCGBlendModeHue);

[hueBlend.layer renderInContext:context];

self.image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext(); }