Ich versuche, das Histogramm eines Bildes mit vImage's @ zu berechnevImageHistogramCalculation_ARGBFFFF, aber ich bekomme einvImage_Error vom TypkvImageNullPointerArgument (Fehlercode a -21772).

Hier ist mein Code:

- (void)histogramForImage:(UIImage *)image {

    //setup inBuffer
    vImage_Buffer inBuffer;

    //Get CGImage from UIImage
    CGImageRef img = image.CGImage;

    //create vImage_Buffer with data from CGImageRef
    CGDataProviderRef inProvider = CGImageGetDataProvider(img);
    CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);

    //The next three lines set up the inBuffer object
    inBuffer.width = CGImageGetWidth(img);
    inBuffer.height = CGImageGetHeight(img);
    inBuffer.rowBytes = CGImageGetBytesPerRow(img);

    //This sets the pointer to the data for the inBuffer object
    inBuffer.data = (void*)CFDataGetBytePtr(inBitmapData);

    //Prepare the parameters to pass to vImageHistogramCalculation_ARGBFFFF
    vImagePixelCount *histogram[4] = {0};
    unsigned int histogram_entries = 4;
    Pixel_F minVal = 0;
    Pixel_F maxVal = 255;
    vImage_Flags flags = kvImageNoFlags;

    vImage_Error error = vImageHistogramCalculation_ARGBFFFF(&inBuffer,
                                                             histogram,
                                                             histogram_entries,
                                                             minVal,
                                                             maxVal,
                                                             flags);
    if (error) {
        NSLog(@"error %ld", error);
    }

    //clean up
    CGDataProviderRelease(inProvider);
}

ch vermute, es hat etwas mit meinem @ zu thistogram -Parameter, der laut Dokumentation "ein Zeiger auf ein Array von vier Histogrammen" sein soll. Erkläre ich es richtig?

Vielen Dank