从CGImage获取RGB像素数据
从CGImage获取RGB像素数据
提问于 2011-05-20 22:18:47
我正在尝试从CGImage访问像素数据。我希望能够以整数形式访问RGB值。我想我对下面的代码已经差不多了：
UIImage* theImage = [UIImage imageNamed:@"rgb.png"];
CGImageRef cgImageRef = CGImageRetain(theImage.CGImage);
CFDataRef* imageData = CGDataProviderCopyData(CGImageGetDataProvider(cgImageRef));
NSLog(@"the data = %@", imageData);这将记录以下内容：
数据= <010002fe fffdff02 0200fe04 0003fc>
该图像是一个5x1的png，按顺序包含一个黑色、白色、红色、绿色和蓝色像素。
我真的不明白我在这里看的是什么。如何获得RGB值的数组，或者类似的值，以便我可以使用它们。
谢谢你，瑞奇
回答 1
Stack Overflow用户
发布于 2011-05-21 05:30:00
下面是一些示例代码，它们将打印一系列关于图像的相关信息，以及图像像素数据的转储。它将在具有alpha通道的图像上工作，以及在没有alpha通道的图像上工作。该代码甚至可以处理不在RGB色彩空间中的图像，尽管我怀疑你可能在iOS上得到任何这样的图像。
将其复制-粘贴到您的项目中，并尝试针对一些图像文件运行它，然后也许您可以根据需要对其进行调整
-(void)imageDump:(NSString*)file
{
UIImage* image = [UIImage imageNamed:file];
CGImageRef cgimage = image.CGImage;
size_t width = CGImageGetWidth(cgimage);
size_t height = CGImageGetHeight(cgimage);
size_t bpr = CGImageGetBytesPerRow(cgimage);
size_t bpp = CGImageGetBitsPerPixel(cgimage);
size_t bpc = CGImageGetBitsPerComponent(cgimage);
size_t bytes_per_pixel = bpp / bpc;
CGBitmapInfo info = CGImageGetBitmapInfo(cgimage);
NSLog(
@"\n"
"===== %@ =====\n"
"CGImageGetHeight: %d\n"
"CGImageGetWidth: %d\n"
"CGImageGetColorSpace: %@\n"
"CGImageGetBitsPerPixel: %d\n"
"CGImageGetBitsPerComponent: %d\n"
"CGImageGetBytesPerRow: %d\n"
"CGImageGetBitmapInfo: 0x%.8X\n"
" kCGBitmapAlphaInfoMask = %s\n"
" kCGBitmapFloatComponents = %s\n"
" kCGBitmapByteOrderMask = 0x%.8X\n"
" kCGBitmapByteOrderDefault = %s\n"
" kCGBitmapByteOrder16Little = %s\n"
" kCGBitmapByteOrder32Little = %s\n"
" kCGBitmapByteOrder16Big = %s\n"
" kCGBitmapByteOrder32Big = %s\n",
file,
(int)width,
(int)height,
CGImageGetColorSpace(cgimage),
(int)bpp,
(int)bpc,
(int)bpr,
(unsigned)info,
(info & kCGBitmapAlphaInfoMask) ? "YES" : "NO",
(info & kCGBitmapFloatComponents) ? "YES" : "NO",
(info & kCGBitmapByteOrderMask),
((info & kCGBitmapByteOrderMask) == kCGBitmapByteOrderDefault) ? "YES" : "NO",
((info & kCGBitmapByteOrderMask) == kCGBitmapByteOrder16Little) ? "YES" : "NO",
((info & kCGBitmapByteOrderMask) == kCGBitmapByteOrder32Little) ? "YES" : "NO",
((info & kCGBitmapByteOrderMask) == kCGBitmapByteOrder16Big) ? "YES" : "NO",
((info & kCGBitmapByteOrderMask) == kCGBitmapByteOrder32Big) ? "YES" : "NO"
);
CGDataProviderRef provider = CGImageGetDataProvider(cgimage);
NSData* data = (id)CGDataProviderCopyData(provider);
[data autorelease];
const uint8_t* bytes = [data bytes];
printf("Pixel Data:\n");
for(size_t row = 0; row < height; row++)
{
for(size_t col = 0; col < width; col++)
{
const uint8_t* pixel =
&bytes[row * bpr + col * bytes_per_pixel];
printf("(");
for(size_t x = 0; x < bytes_per_pixel; x++)
{
printf("%.2X", pixel[x]);
if( x < bytes_per_pixel - 1 )
printf(",");
}
printf(")");
if( col < width - 1 )
printf(", ");
}
printf("\n");
}
}下面是我尝试过的两个图像的一些示例输出。它们都是5x3 rgb。"a.png“图像有一个alpha通道，而"b.rgb”没有。
===== a.png =====
CGImageGetHeight: 5
CGImageGetWidth: 3
CGImageGetColorSpace: <CGColorSpace 0x4d08ff0> (kCGColorSpaceDeviceRGB)
CGImageGetBitsPerPixel: 32
CGImageGetBitsPerComponent: 8
CGImageGetBytesPerRow: 20
CGImageGetBitmapInfo: 0x00000003
kCGBitmapAlphaInfoMask = YES
kCGBitmapFloatComponents = NO
kCGBitmapByteOrderMask = NO
kCGBitmapByteOrderDefault = NO
kCGBitmapByteOrder16Little = NO
kCGBitmapByteOrder32Little = NO
kCGBitmapByteOrder16Big = NO
kCGBitmapByteOrder32Big = NO
Pixel Data:
(00,00,00,FF), (FF,FF,FF,FF), (FF,00,00,FF), (00,FF,00,FF), (00,00,FF,FF)
(00,00,00,FF), (FF,FF,FF,FF), (FF,00,00,FF), (00,FF,00,FF), (00,00,FF,FF)
(FF,FF,FF,00), (FF,FF,FF,00), (FF,FF,FF,00), (FF,FF,FF,00), (FF,FF,FF,00)
===== b.png =====
CGImageGetHeight: 5
CGImageGetWidth: 3
CGImageGetColorSpace: <CGColorSpace 0x4d08ff0> (kCGColorSpaceDeviceRGB)
CGImageGetBitsPerPixel: 24
CGImageGetBitsPerComponent: 8
CGImageGetBytesPerRow: 15
CGImageGetBitmapInfo: 0x00000000
kCGBitmapAlphaInfoMask = NO
kCGBitmapFloatComponents = NO
kCGBitmapByteOrderMask = NO
kCGBitmapByteOrderDefault = NO
kCGBitmapByteOrder16Little = NO
kCGBitmapByteOrder32Little = NO
kCGBitmapByteOrder16Big = NO
kCGBitmapByteOrder32Big = NO
Pixel Data:
(00,00,00), (FF,FF,FF), (FF,00,00), (00,FF,00), (00,00,FF)
(00,00,00), (FF,FF,FF), (FF,00,00), (00,FF,00), (00,00,FF)
(00,00,00), (FF,FF,FF), (FF,00,00), (00,FF,00), (00,00,FF)页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/6073259
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