使用物镜C将RGB彩色图像更改为灰度图像 [英] Changing RGB color image to Grayscale image using Objective C
本文介绍了使用物镜C将RGB彩色图像更改为灰度图像的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在开发一个将彩色图像更改为灰色图像的应用程序.但是,有些图片是错误的.我不知道代码有什么问题.也许我输入的参数有误,请帮忙.
I was developing a application that changes color image to gray image. However, some how the picture comes out wrong. I dont know what is wrong with the code. maybe the parameter that i put in is wrong please help.
UIImage *c = [UIImage imageNamed:@"downRed.png"];
CGImageRef cRef = CGImageRetain(c.CGImage);
NSData* pixelData = (NSData*) CGDataProviderCopyData(CGImageGetDataProvider(cRef));
size_t w = CGImageGetWidth(cRef);
size_t h = CGImageGetHeight(cRef);
unsigned char* pixelBytes = (unsigned char *)[pixelData bytes];
unsigned char* greyPixelData = (unsigned char*) malloc(w*h);
for (int y = 0; y < h; y++) {
for(int x = 0; x < w; x++){
int iter = 4*(w*y+x);
int red = pixe lBytes[iter];
int green = pixelBytes[iter+1];
int blue = pixelBytes[iter+2];
greyPixelData[w*y+x] = (unsigned char)(red*0.3 + green*0.59+ blue*0.11);
int value = greyPixelData[w*y+x];
}
}
CFDataRef imgData = CFDataCreate(NULL, greyPixelData, w*h);
CGDataProviderRef imgDataProvider = CGDataProviderCreateWithCFData(imgData);
size_t width = CGImageGetWidth(cRef);
size_t height = CGImageGetHeight(cRef);
size_t bitsPerComponent = 8;
size_t bitsPerPixel = 8;
size_t bytesPerRow = CGImageGetWidth(cRef);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
CGBitmapInfo info = kCGImageAlphaNone;
CGFloat *decode = NULL;
BOOL shouldInteroplate = NO;
CGColorRenderingIntent intent = kCGRenderingIntentDefault;
CGDataProviderRelease(imgDataProvider);
CGImageRef throughCGImage = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpace, info, imgDataProvider, decode, shouldInteroplate, intent);
UIImage* newImage = [UIImage imageWithCGImage:throughCGImage];
CGImageRelease(throughCGImage);
newImageView.image = newImage;
推荐答案
如果某人想要对包含透明部分的图像进行灰度处理,digipeople提供的解决方案将在其周围带有黑色蒙版.改用它来保持透明.
If someone wants to gray scale images that contain transparent parts the solution offered by digipeople will have a black mask around it. Use this instead to leave the transparent as it is.
- (UIImage *)imageToGreyImage:(UIImage *)image {
// Create image rectangle with current image width/height
CGFloat actualWidth = image.size.width;
CGFloat actualHeight = image.size.height;
CGRect imageRect = CGRectMake(0, 0, actualWidth, actualHeight);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
CGContextRef context = CGBitmapContextCreate(nil, actualWidth, actualHeight, 8, 0, colorSpace, kCGImageAlphaNone);
CGContextDrawImage(context, imageRect, [image CGImage]);
CGImageRef grayImage = CGBitmapContextCreateImage(context);
CGColorSpaceRelease(colorSpace);
CGContextRelease(context);
context = CGBitmapContextCreate(nil, actualWidth, actualHeight, 8, 0, nil, kCGImageAlphaOnly);
CGContextDrawImage(context, imageRect, [image CGImage]);
CGImageRef mask = CGBitmapContextCreateImage(context);
CGContextRelease(context);
UIImage *grayScaleImage = [UIImage imageWithCGImage:CGImageCreateWithMask(grayImage, mask) scale:image.scale orientation:image.imageOrientation];
CGImageRelease(grayImage);
CGImageRelease(mask);
// Return the new grayscale image
return grayScaleImage;
}
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