UIImage 上的黑白 Photoshop 效果

Question

您好，我想在 UIImage 上创建以下黑白 Photoshop 效果

https://drive.google.com/file/d/0B5dHxpdDwpPec3dPTWdLVnNhZFk/view?usp=sharing

您可以在其中更改六种颜色（红色、黄色、绿色、青色、蓝色、洋红色）中每一种的亮度

我用它把图像变成黑白的，但它不允许我改变特定的颜色

self.imageView.image = chosenImage;

CIImage *beginImage = [CIImage imageWithCGImage:chosenImage.CGImage];

CIImage *blackAndWhite = [CIFilter filterWithName:@"CIColorControls" keysAndValues:kCIInputImageKey, beginImage, @"inputBrightness", [NSNumber numberWithFloat:0.0], @"inputContrast", [NSNumber numberWithFloat:1.1], @"inputSaturation", [NSNumber numberWithFloat:0.0], nil].outputImage;
CIImage *output = [CIFilter filterWithName:@"CIExposureAdjust" keysAndValues:kCIInputImageKey, blackAndWhite, @"inputEV", [NSNumber numberWithFloat:0.7], nil].outputImage;

CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef cgiimage = [context createCGImage:output fromRect:output.extent];
UIImage *newImage = [UIImage imageWithCGImage:cgiimage];

self.imageView.image = newImage;

感谢您的宝贵时间

Answer 1

我认为您可以使用以下函数实现该效果：

- (UIImage *)grayScaleImageWith:(UIImage *)image blackPoint:(CGFloat)blackPoint whitePoint:(CGFloat)whitePoint andGamma:(CGFloat)gamma  {


    // Create image rectangle with current image width/height
    CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height);

    // Grayscale color space
    CGColorSpaceRef colorSpace = CGColorSpaceCreateCalibratedGray(whitePoint, blackPoint, gamma);

    // Create bitmap content with current image size and grayscale colorspace
    CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, colorSpace, kCGImageAlphaNone);

    // Draw image into current context, with specified rectangle
    // using previously defined context (with grayscale colorspace)
    CGContextDrawImage(context, imageRect, [image CGImage]);

    // Create bitmap image info from pixel data in current context
    CGImageRef imageRef = CGBitmapContextCreateImage(context);

    // Create a new UIImage object
    UIImage *newImage = [UIImage imageWithCGImage:imageRef];

    // Release colorspace, context and bitmap information
    CGColorSpaceRelease(colorSpace);
    CGContextRelease(context);
    CFRelease(imageRef);

    // Return the new grayscale image
    return newImage; 
}

然后用 UI 上选择的值填充黑白值：

CGFloat black[3] = { 0, 0, 0 }; // replace content with values from interface
CGFloat white[3] = { 100, 100, 100 }; // replace content with values from interface

[self grayScaleImageWith:image blackPoint:black whitePoint:white andGamma:1.8f];

我还没有测试过这段代码，但我希望它至少能为您指明正确的方向。

UIImage 上的黑白 Photoshop 效果

Black and White Photoshop effect on UIImage

objective-c

uiimageview

uiimage

ios