d1xlord d1xlord - 1 year ago 507
iOS Question

How to convert from YUV to CIImage for iOS

I am trying to convert a YUV image to CIIMage and ultimately UIImage. I am fairly novice at these and trying to figure out an easy way to do it. From what I have learnt, from iOS6 YUV can be directly used to create CIImage but as I am trying to create it the CIImage is only holding a nil value. My code is like this ->

NSLog(@"Started DrawVideoFrame\n");

CVPixelBufferRef pixelBuffer = NULL;

CVReturn ret = CVPixelBufferCreateWithBytes(
kCFAllocatorDefault, iWidth, iHeight, kCVPixelFormatType_420YpCbCr8BiPlanarFullRange,
lpData, bytesPerRow, 0, 0, 0, &pixelBuffer

if(ret != kCVReturnSuccess)
NSLog(@"CVPixelBufferRelease Failed");

NSDictionary *opt = @{ (id)kCVPixelBufferPixelFormatTypeKey :
@(kCVPixelFormatType_420YpCbCr8BiPlanarFullRange) };

CIImage *cimage = [CIImage imageWithCVPixelBuffer:pixelBuffer options:opt];
NSLog(@"CURRENT CIImage -> %p\n", cimage);

UIImage *image = [UIImage imageWithCIImage:cimage scale:1.0 orientation:UIImageOrientationUp];
NSLog(@"CURRENT UIImage -> %p\n", image);

Here the lpData is the YUV data which is an array of unsigned character.

This also looks interesting : vImageMatrixMultiply, can't find any example on this. Can anyone help me with this?

Answer Source

I have also faced with this similar problem. I was trying to Display YUV(NV12) formatted data to the screen. This solution is working in my project...

//YUV(NV12)-->CIImage--->UIImage Conversion
NSDictionary *pixelAttributes = @{kCVPixelBufferIOSurfacePropertiesKey : @{}};
CVPixelBufferRef pixelBuffer = NULL;

CVReturn result = CVPixelBufferCreate(kCFAllocatorDefault,
                                      (__bridge CFDictionaryRef)(pixelAttributes),

unsigned char *yDestPlane = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0);

// Here y_ch0 is Y-Plane of YUV(NV12) data.
memcpy(yDestPlane, y_ch0, 640 * 480); 
unsigned char *uvDestPlane = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 1);

// Here y_ch1 is UV-Plane of YUV(NV12) data. 
memcpy(uvDestPlane, y_ch1, 640*480/2);
CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);

if (result != kCVReturnSuccess) {
    NSLog(@"Unable to create cvpixelbuffer %d", result);

// CIImage Conversion    
CIImage *coreImage = [CIImage imageWithCVPixelBuffer:pixelBuffer];

CIContext *MytemporaryContext = [CIContext contextWithOptions:nil];
CGImageRef MyvideoImage = [MytemporaryContext createCGImage:coreImage
                                                    fromRect:CGRectMake(0, 0, 640, 480)];

// UIImage Conversion
UIImage *Mynnnimage = [[UIImage alloc] initWithCGImage:MyvideoImage 


Here I am showing data structure of YUV(NV12) data and how we can get the Y-Plane(y_ch0) and UV-Plane(y_ch1) which is used to create CVPixelBufferRef. Let's look at the YUV(NV12) data structure.. enter image description here If we look at the picture we can get following information about YUV(NV12),

  • Total Frame Size = Width * Height * 3/2,
  • Y-Plane Size = Frame Size * 2/3,
  • UV-Plane size = Frame Size * 1/3,
  • Data stored in Y-Plane -->{Y1, Y2, Y3, Y4, Y5.....}.
  • U-Plane-->(U1, V1, U2, V2, U3, V3,......}.

I hope it will be helpful to all. :) Have fun with IOS Development :D

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