在IOS中从UIImagview检测黑色的最左侧点

我无法从检测

UIImageView

中找到最左边的点/帧/位置。我尝试从

UIImageView

检测黑色像素，如下所示：

-(void)Black_findcolor
{
    UIImage *image = imgview.image;//imgview from i want to detect the most black color pixels.

    CFDataRef pixelData = CGDataProviderCopyData(CGImageGetDataProvider(image.CGImage));
    int myWidth = CGImageGetWidth(image.CGImage);
    int myHeight = CGImageGetHeight(image.CGImage);
    const UInt8 *pixels = CFDataGetBytePtr(pixelData);
    UInt8 blackThreshold = 10 ;
  //  UInt8 alphaThreshold = 100;
    int bytesPerPixel_ = 4;
    CGFloat Xvalue,Yvalue;
    int x = 0,y=0;
    for( x = 0; x < myWidth; x++)
    {
        for( y = 0; y < myHeight; y++)
        {
            int pixelStartIndex = (x + (y * myWidth)) * bytesPerPixel_;
            UInt8 alphaVal = pixels[pixelStartIndex];
            UInt8 redVal = pixels[pixelStartIndex + 1];
            UInt8 greenVal = pixels[pixelStartIndex + 2];
            UInt8 blueVal = pixels[pixelStartIndex + 3];

            if(redVal < blackThreshold || blueVal < blackThreshold || greenVal < blackThreshold || alphaVal < blackThreshold)
            {
                NSLog(@"x =%d, y = %d", x, y);
           }
        }
    }
}

那么，有谁能给我一些想法或建议，如何设置imgpin1最左侧黑色像素的帧或位置呢

如果需要任何其他信息，请告诉我

提前感谢。

已编辑 请看一下我编辑过的答案

    //You need to get resized image from your imageView in case of sizeToFit etc.
    float oldWidth = yourImageView.image.size.width;
    float scaleFactor = yourImageView.frame.size.width / oldWidth;

    float newHeight = yourImageView.image.size.height * scaleFactor;
    float newWidth = oldWidth * scaleFactor;

    UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight));
    [yourImageView.image drawInRect:CGRectMake(0, 0, newWidth, newHeight)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();


    CGSize size = newImage.size;
    int width = size.width;
    int height = size.height;
    int xCoord = width, yCoord = height;
    UInt8 blackThreshold = 10;


    // raw data will be assigned into this array
    uint32_t *pixels = (uint32_t *) malloc(width * height * sizeof(uint32_t));

    // clear the pixels so any transparency is preserved
    memset(pixels, 0, width * height * sizeof(uint32_t));

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    // create a context with RGBA pixels
    CGContextRef context = CGBitmapContextCreate(pixels, width, height, 8, width * sizeof(uint32_t), colorSpace,
                                                 kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedLast);

    // fill in the pixels array
    CGContextDrawImage(context, CGRectMake(0, 0, width, height), [yourImageView.image CGImage]);

    for(int y = 0; y < height; y++) {
        for(int x = 0; x < width; x++) {
            uint8_t *rgbaPixel = (uint8_t *) &pixels[y * width + x];

            // convert to grayscale using recommended method: http://en.wikipedia.org/wiki/Grayscale#Converting_color_to_grayscale
            uint32_t gray = 0.3 * rgbaPixel[1] + 0.59 * rgbaPixel[2] + 0.11 * rgbaPixel[3];

            if (gray < blackThreshold)
            {
                if (x<xCoord)
                {
                    xCoord = x;
                    yCoord = y;
                    NSLog(@"X:%d Y:%d",xCoord,yCoord);
                }
            }

        }
    }

    // we're done with the context and pixels
    CGContextRelease(context);
    free(pixels);

    imgPin1.center=CGPointMake(xCoord, yCoord);

//如果存在sizeToFit等问题，您需要从imageView中获取已调整大小的图像。
float oldWidth=yourImageView.image.size.width；
float scaleFactor=yourImageView.frame.size.width/oldWidth；
float newHeight=yourImageView.image.size.height*scaleFactor；
float newWidth=oldWidth*scaleFactor；
UIGraphicsBeginImageContext（CGSizeMake（newWidth，newHeight））；
[yourImageView.image drawInRect:CGRectMake（0，0，newWidth，newHeight）]；
UIImage*newImage=UIGraphicsGetImageFromCurrentImageContext（）；
UIGraphicsSendImageContext（）；
CGSize size=newImage.size；
int width=size.width；
int height=size.height；
int xCoord=宽度，yCoord=高度；
UInt8黑阈值=10；
//原始数据将分配到此数组中
uint32_t*像素=（uint32_t*）malloc（宽度*高度*尺寸（uint32_t））；
//清除像素以保留任何透明度
memset（像素，0，宽度*高度*大小（uint32_t））；
CGColorSpaceRef colorSpace=CGColorSpaceCreateDeviceRGB（）；
//使用RGBA像素创建上下文
CGContextRef context=CGBitmapContextCreate（像素、宽度、高度、8、宽度*sizeof（uint32_t）、颜色空间、，
kCGBitmapByteOrder32Little | KCGimageAlphaPremultipledLast）；
//填充像素数组
CGContextDrawImage（上下文，CGRectMake（0，0，宽度，高度），[yourImageView.image CGImage]）；
对于（int y=0；y如果（X感谢您的回答…但在我的UIImageview上没有检测到任何黑色像素…您能帮我吗？当然。让我在我的xcode中尝试一下。您使用的是什么图像？编辑了我的问题，我使用了该图像。在这一点上，我想将黑色条带作为检测。请查看我编辑的答案。按照您的要求进行测试和工作ired.非常感谢…你能告诉我什么是scater吗？其他方面，你能在这里分享整个项目吗…对我来说很好。所以你想要你的pin在卡片的开头黑色条纹是吗？是的，完全正确…最左边和最右边…是的，我正在测试一些变体。过一会儿会让你知道的
    //You need to get resized image from your imageView in case of sizeToFit etc.
    float oldWidth = yourImageView.image.size.width;
    float scaleFactor = yourImageView.frame.size.width / oldWidth;

    float newHeight = yourImageView.image.size.height * scaleFactor;
    float newWidth = oldWidth * scaleFactor;

    UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight));
    [yourImageView.image drawInRect:CGRectMake(0, 0, newWidth, newHeight)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();


    CGSize size = newImage.size;
    int width = size.width;
    int height = size.height;
    int xCoord = width, yCoord = height;
    UInt8 blackThreshold = 10;


    // raw data will be assigned into this array
    uint32_t *pixels = (uint32_t *) malloc(width * height * sizeof(uint32_t));

    // clear the pixels so any transparency is preserved
    memset(pixels, 0, width * height * sizeof(uint32_t));

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    // create a context with RGBA pixels
    CGContextRef context = CGBitmapContextCreate(pixels, width, height, 8, width * sizeof(uint32_t), colorSpace,
                                                 kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedLast);

    // fill in the pixels array
    CGContextDrawImage(context, CGRectMake(0, 0, width, height), [yourImageView.image CGImage]);

    for(int y = 0; y < height; y++) {
        for(int x = 0; x < width; x++) {
            uint8_t *rgbaPixel = (uint8_t *) &pixels[y * width + x];

            // convert to grayscale using recommended method: http://en.wikipedia.org/wiki/Grayscale#Converting_color_to_grayscale
            uint32_t gray = 0.3 * rgbaPixel[1] + 0.59 * rgbaPixel[2] + 0.11 * rgbaPixel[3];

            if (gray < blackThreshold)
            {
                if (x<xCoord)
                {
                    xCoord = x;
                    yCoord = y;
                    NSLog(@"X:%d Y:%d",xCoord,yCoord);
                }
            }

        }
    }

    // we're done with the context and pixels
    CGContextRelease(context);
    free(pixels);

    imgPin1.center=CGPointMake(xCoord, yCoord);