[英]How do I use the Accelerate Framework With Core Graphics?
我有一個項目。 它基本上是從iPhone相機拍照並對照片應用了一些效果。 在我應用效果之前,我使用核心圖形將圖像縮放到合適的大小。 縮放和旋轉圖像后,我使用Accelerate框架(vImage)來創建效果。 我的問題是在應用效果之后它最終變成了一些藍色的圖像。 但是,如果我不使用核心圖形縮放圖像,則這種偏藍的外觀不會發生。
我使用的縮放代碼來自這篇文章。
這是我的代碼應用效果:
- (UIImage *)applyFiltertoImage:(UIImage *)img
{
CGImageRef image = img.CGImage;
vImage_Buffer inBuffer, outBuffer;
void *pixelBuffer;
CGDataProviderRef inProvider = CGImageGetDataProvider(image);
CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);
inBuffer.width = CGImageGetWidth(image);
inBuffer.height = CGImageGetHeight(image);
inBuffer.rowBytes = CGImageGetBytesPerRow(image);
inBuffer.data = (void *)CFDataGetBytePtr(inBitmapData);
pixelBuffer = malloc(CGImageGetBytesPerRow(image) * CGImageGetHeight(image));
if (pixelBuffer == NULL) {
NSLog(@"No buffer");
}
outBuffer.data = pixelBuffer;
outBuffer.width = CGImageGetWidth(image);
outBuffer.height = CGImageGetHeight(image);
outBuffer.rowBytes = CGImageGetBytesPerRow(image);
vImageConvolve_ARGB8888(&inBuffer, &outBuffer, NULL, 0, 0, self.kernel, self.size, self.size, self.divisor, NULL, kvImageEdgeExtend);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef ctx = CGBitmapContextCreate(outBuffer.data,
outBuffer.width,
outBuffer.height,
8,
outBuffer.rowBytes,
colorSpace,
kCGImageAlphaNoneSkipLast);
CGImageRef imageRef = CGBitmapContextCreateImage(ctx);
UIImage *blurredImage = [UIImage imageWithCGImage:imageRef];
CGContextRelease(ctx);
CGColorSpaceRelease(colorSpace);
free(pixelBuffer);
CFRelease(inBitmapData);
CGImageRelease(imageRef);
return blurredImage;
}
嘗試讓vImage為您初始化值。 vImageBuffer_InitWithCGImage
可以幫助您避免一些痛苦。
- (UIImage *)applyFiltertoImage:(UIImage *)image
CGImageRef originalImageRef = image.CGImage;
CGColorSpaceRef originalColorSpace = CGColorSpaceRetain(CGImageGetColorSpace(originalImageRef));
if (_pixelBuffer == NULL) {
_pixelBuffer = malloc(CGImageGetBytesPerRow(originalImageRef) * CGImageGetHeight(originalImageRef));
}
vImage_CGImageFormat inputImageFormat =
{
.bitsPerComponent = (uint32_t) CGImageGetBitsPerComponent(originalImageRef),
.bitsPerPixel = (uint32_t) CGImageGetBitsPerComponent(originalImageRef) * (uint32_t)(CGColorSpaceGetNumberOfComponents(originalColorSpace) + (kCGImageAlphaNone != CGImageGetAlphaInfo(originalImageRef))),
.colorSpace = originalColorSpace,
.bitmapInfo = CGImageGetBitmapInfo(originalImageRef),
.version = 0,
.decode = NULL,
.renderingIntent = kCGRenderingIntentDefault
};
vImage_Buffer inputImageBuffer;
vImageBuffer_InitWithCGImage(&inputImageBuffer, &inputImageFormat, NULL, originalImageRef, kvImageNoFlags);
vImage_Buffer outputImageBuffer = {
.data = _pixelBuffer,
.width = CGImageGetWidth(originalImageRef),
.height = CGImageGetHeight(originalImageRef),
.rowBytes = CGImageGetBytesPerRow(originalImageRef)
};
vImage_Error error;
error = vImageConvolve_ARGB8888(&inputImageBuffer,
&outputImageBuffer,
NULL,
0,
0,
self.kernel,
self.size,
self.divisor,
NULL,
kvImageEdgeExtend);
if (error) {
NSLog(@"vImage error %zd", error);
}
free(inputImageBuffer.data);
vImage_CGImageFormat outFormat =
{
.bitsPerComponent = (uint32_t) CGImageGetBitsPerComponent(originalImageRef),
.bitsPerPixel = (uint32_t) CGImageGetBitsPerComponent(originalImageRef) * (uint32_t)(CGColorSpaceGetNumberOfComponents(originalColorSpace) + (kCGImageAlphaNone != CGImageGetAlphaInfo(originalImageRef))),
.colorSpace = originalColorSpace,
.bitmapInfo = CGImageGetBitmapInfo(originalImageRef),
.version = 0,
.decode = NULL,
.renderingIntent = kCGRenderingIntentDefault
};
CGImageRef modifiedImageRef = vImageCreateCGImageFromBuffer(&outputImageBuffer,
&outFormat,
NULL,
NULL,
kvImageNoFlags,
&error);
CGColorSpaceRelease(originalColorSpace);
UIImage *returnImage = [UIImage imageWithCGImage:modifiedImageRef];
CGImageRelease(modifiedImageRef);
return returnImage;
}
每個圖像一次創建_inputImageBuffer,_outputImageBuffer和_outputImageFormat,然后只需將過濾器重新應用到源圖像。 一旦vImage變暖,它將從呼叫開始削減幾毫秒。
- (UIImage *)applyFilter
vImage_Error error;
error = vImageConvolve_ARGB8888(&_inputImageBuffer,
&_outputImageBuffer,
NULL,
0,
0,
self.kernel,
self.size,
self.divisor,
NULL,
kvImageEdgeExtend);
if (error) {
NSLog(@"vImage error %zd", error);
}
CGImageRef modifiedImageRef = vImageCreateCGImageFromBuffer(&_outputImageBuffer,
&_outputImageFormat,
NULL,
NULL,
kvImageNoFlags,
&error);
UIImage *returnImage = [UIImage imageWithCGImage:modifiedImageRef];
CGImageRelease(modifiedImageRef);
return returnImage;
}
通常,強烈的色調意味着顏色通道順序在沿途的某處翻譯時丟失,例如您創建了帶有BGRA數據的CG圖像,但它實際上是ARGB。
你看過vImage_Utilities.h嗎?
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