如何从cvPixelBuffer读取单个像素

您必须使用cvPixelBuffer API来获得通过不安全的指针操作访问数据的正确格式。以下是基本方法:

CVPixelBufferRef pixelBuffer = _lastDepthData.depthDataMap;

CVPixelBufferLockBaseAddress(pixelBuffer, 0);

size_t cols = CVPixelBufferGetWidth(pixelBuffer);
size_t rows = CVPixelBufferGetHeight(pixelBuffer);
Float32 *baseAddress = CVPixelBufferGetBaseAddress( pixelBuffer );

// This next step is not necessary, but I include it here for illustration,
// you can get the type of pixel format, and it is associated with a kCVPixelFormatType
// this can tell you what type of data it is e.g. in this case Float32

OSType type = CVPixelBufferGetPixelFormatType( pixelBuffer);

if (type != kCVPixelFormatType_DepthFloat32) {
    NSLog(@"Wrong type");
}

// Arbitrary values of x and y to sample
int x = 20; // must be lower that cols
int y = 30; // must be lower than rows

// Get the pixel.  You could iterate here of course to get multiple pixels!
int baseAddressIndex = y  * (int)cols + x;
const Float32 pixel = baseAddress[baseAddressIndex];

CVPixelBufferUnlockBaseAddress( pixelBuffer, 0 );

请注意,首先需要确定的是cvPixelBuffer中的数据类型-如果您不知道这一点,则可以使用cvPixelBufferGetPixelFormatType()查找。在本例中,我在float32处获取深度数据,如果您使用的是另一种类型,例如float16,那么您将需要用该类型替换所有出现的float32。

请注意,使用cvPixelBufferLockBaseAddress和cvPixelBufferUnlockBaseAddress锁定和解锁基址很重要。