要使用equalizeHistogram函数获得每秒30帧,必须将图像去交错(从ARGBxxxx转换为PlanarX),并仅使R(红)G(绿)B(蓝)均衡化;如果您均衡化A(透明度),则帧率将降至至少24。
以下是完全按照您要求的代码,速度快,效果佳:
- (CVPixelBufferRef)copyRenderedPixelBuffer:(CVPixelBufferRef)pixelBuffer {
CVPixelBufferLockBaseAddress( pixelBuffer, 0 );
unsigned char *base = (unsigned char *)CVPixelBufferGetBaseAddress( pixelBuffer );
size_t width = CVPixelBufferGetWidth( pixelBuffer );
size_t height = CVPixelBufferGetHeight( pixelBuffer );
size_t stride = CVPixelBufferGetBytesPerRow( pixelBuffer );
vImage_Buffer _img = {
.data = base,
.height = height,
.width = width,
.rowBytes = stride
};
vImage_Error err;
vImage_Buffer _dstA, _dstR, _dstG, _dstB;
err = vImageBuffer_Init( &_dstA, height, width, 8 * sizeof( uint8_t ), kvImageNoFlags);
if (err != kvImageNoError)
NSLog(@"vImageBuffer_Init (alpha) error: %ld", err);
err = vImageBuffer_Init( &_dstR, height, width, 8 * sizeof( uint8_t ), kvImageNoFlags);
if (err != kvImageNoError)
NSLog(@"vImageBuffer_Init (red) error: %ld", err);
err = vImageBuffer_Init( &_dstG, height, width, 8 * sizeof( uint8_t ), kvImageNoFlags);
if (err != kvImageNoError)
NSLog(@"vImageBuffer_Init (green) error: %ld", err);
err = vImageBuffer_Init( &_dstB, height, width, 8 * sizeof( uint8_t ), kvImageNoFlags);
if (err != kvImageNoError)
NSLog(@"vImageBuffer_Init (blue) error: %ld", err);
err = vImageConvert_ARGB8888toPlanar8(&_img, &_dstA, &_dstR, &_dstG, &_dstB, kvImageNoFlags);
if (err != kvImageNoError)
NSLog(@"vImageConvert_ARGB8888toPlanar8 error: %ld", err);
err = vImageEqualization_Planar8(&_dstR, &_dstR, kvImageNoFlags);
if (err != kvImageNoError)
NSLog(@"vImageEqualization_Planar8 (red) error: %ld", err);
err = vImageEqualization_Planar8(&_dstG, &_dstG, kvImageNoFlags);
if (err != kvImageNoError)
NSLog(@"vImageEqualization_Planar8 (green) error: %ld", err);
err = vImageEqualization_Planar8(&_dstB, &_dstB, kvImageNoFlags);
if (err != kvImageNoError)
NSLog(@"vImageEqualization_Planar8 (blue) error: %ld", err);
err = vImageConvert_Planar8toARGB8888(&_dstA, &_dstR, &_dstG, &_dstB, &_img, kvImageNoFlags);
if (err != kvImageNoError)
NSLog(@"vImageConvert_Planar8toARGB8888 error: %ld", err);
err = vImageContrastStretch_ARGB8888( &_img, &_img, kvImageNoError );
if (err != kvImageNoError)
NSLog(@"vImageContrastStretch_ARGB8888 error: %ld", err);
free(_dstA.data);
free(_dstR.data);
free(_dstG.data);
free(_dstB.data);
CVPixelBufferUnlockBaseAddress( pixelBuffer, 0 );
return (CVPixelBufferRef)CFRetain( pixelBuffer );
请注意,即使我对 alpha 通道进行了操作,我仍然分配了它。这是因为在 ARGB8888 和 Planar8 之间来回转换需要分配和引用 alpha 通道缓冲区。无论如何,性能和质量都得到了提升。
另外,请注意,在将 Planar8 缓冲区转换为单个 ARGB8888 缓冲区后,我执行了对比度拉伸;这是因为与直方图均衡化函数逐个通道应用相比,它更快,并且获得了相同的结果(对比度拉伸函数不会像直方图均衡化一样导致 alpha 通道失真)。