iOSで使える色々な画像形式の相互変換

2017/02/14「CMSampleBuffer - UIImage」を追記

毎回忘れるのでまとめました。
メモ程度なので何かもっと良い方法あるとかリークするとかあったら教えて下さい。

#CMSampleBuffer - UIImage
```objc
//CMSampleBufferRefからUIImage
-(UIImage *)imageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer{
  
  CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
  
  // ピクセルバッファのベースアドレスをロックする
  CVPixelBufferLockBaseAddress(imageBuffer, 0);
  
  // Get information of the image
  uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 0);
  
  size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
  size_t width = CVPixelBufferGetWidth(imageBuffer);
  size_t height = CVPixelBufferGetHeight(imageBuffer);
  
  // RGBの色空間
  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
  
  CGContextRef newContext = CGBitmapContextCreate(baseAddress,
                                                  width,
                                                  height,
                                                  8,
                                                  bytesPerRow,
                                                  colorSpace,
                                                  kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
  
  CGImageRef cgImage = CGBitmapContextCreateImage(newContext);
  
  CGContextRelease(newContext);
  CGColorSpaceRelease(colorSpace);
  
  UIImage *rtnImage = [UIImage imageWithCGImage:cgImage scale:1.0 orientation:UIImageOrientationUp];
  
  CVPixelBufferUnlockBaseAddress(imageBuffer, 0);
  CGImageRelease(cgImage);
    
  return rtnImage;
}

```

#UIImage - CGImage
```objc:uiimage-cgimage.m
//UIImageからCGImage
CGImageRef cgimage = uiimage.CGImage;

//CGImageからUIImage
UIImage *uiimage = [UIImage imageWithCGImage:cgimage];
CGImageRelease(cgimage);
```

#CIImage - CGImage
```objc:uiimage-ciimage.m
//CIImageからCGImage
//[CIContext new]はダメ 2016/06/08更新
CGImageRef cgimage = [[CIContext contextWithOptions:nil] createCGImage:ciimage fromRect:ciimage.extent];

//CGImageからCIImage
CIImage *ciimage = [CIImage imageWithCGImage:cgimage];
```

#vImage - CGImage
```objc:vimage-cgimage.m
    /*
     * format
     * 
     *      typedef struct vImage_CGImageFormat
     *      {
     *          uint32_t                bitsPerComponent;
     *          uint32_t                bitsPerPixel;       
     *          CGColorSpaceRef         colorSpace;         
     *          CGBitmapInfo            bitmapInfo;         
     *          uint32_t                version;            
     *          const CGFloat *         decode;
     *          CGColorRenderingIntent  renderingIntent;
     *      }vImage_CGImageFormat;
    
     *      例
     *      ARGB8888     ->  {8, 32, NULL, alpha first, 0, NULL, kCGRenderingIntentDefault}     alpha first = { kCGImageAlphaFirst, kCGImageAlphaPremultipliedFirst, kCGImageAlphaNoneSkipFirst }
     *      RGBA8888     ->  {8, 32, NULL, alpha last,  0, NULL, kCGRenderingIntentDefault}     alpha last  = { kCGImageAlphaLast,  kCGImageAlphaPremultipliedLast,  kCGImageAlphaNoneSkipLast }
     *      BGRA8888     ->  {8, 32, NULL, alpha first | kCGBitmapByteOrder32Little, 0, NULL, kCGRenderingIntentDefault}
     *      RGB888       ->  {8, 24, NULL, kCGImageAlphaNone | kCGBitmapByteOrderDefault, 0, NULL, kCGRenderingIntentDefault}
     *      RGB565       ->  {5, 16, NULL, kCGImageAlphaNone | kCGBitmapByteOrder16Little, 0, NULL, kCGRenderingIntentDefault}
     *      ARGB1555     ->  {5, 16, NULL, alpha first | kCGBitmapByteOrder16Little, 0, NULL, kCGRenderingIntentDefault}
     *      RGBA16F      ->  {16, 64, NULL, alpha last | kCGBitmapFloatComponents | kCGBitmapByteOrder16Little, 0, NULL, kCGRenderingIntentDefault }
     *      CMYK8888     ->  {8, 32, CGColorSpaceCreateDeviceCMYK(), kCGImageAlphaNone, 0, NULL, kCGRenderingIntentDefault  }
     *      ARGBFFFF premultiplied    ->  {32, 128, NULL, kCGImageAlphaPremultipliedFirst | kCGBitmapFloatComponents | kCGBitmapByteOrder32Little, 0, NULL, kCGRenderingIntentDefault }
     *      ARGBFFFF not-premultiplied -> {32, 128, NULL, kCGImageAlphaFirst | kCGBitmapFloatComponents | kCGBitmapByteOrder32Little, 0, NULL, kCGRenderingIntentDefault }
     *      ARGBFFFF, alpha = 1 ->        {32, 128, NULL, kCGImageAlphaNoneSkipFirst | kCGBitmapFloatComponents | kCGBitmapByteOrder32Little, 0, NULL, kCGRenderingIntentDefault }

     *      uiimageviewに表示する時用のformat
     *      vImage_CGImageFormat format = {
     *          .bitsPerComponent = 8,
     *          .bitsPerPixel = 32,
     *          .bitmapInfo = kCGBitmapByteOrderDefault | kCGImageAlphaLast,  //RGBA8888
     *      }; // .colorspace, .version, .renderingIntent and .decode all initialized to 0 per C rules
     */

//vImageからCGImage
-(CGImageRef)vImageToCGImage:(vImage_Buffer)vimage withFormat:(vImage_CGImageFormat) format{
  vImage_Error error;
  CGImageRef cgimage = vImageCreateCGImageFromBuffer( &vimage, &format, NULL, NULL, kvImageNoFlags, &error);
  if (error != kvImageNoError) {
     NSLog(@"[VIImage ERROR][No %d]", (int)error);
  }
  
  return cgimage;
}


//CGImageからvImage
-(vImage_Buffer)CGImageToVImage:(CGImageRef)cgimage withFormat:(vImage_CGImageFormat) format{
  vImage_Buffer vimage;
  vImage_Error error = vImageBuffer_InitWithCGImage( &vimage, &format, NULL, cgimage, kvImageNoFlags );
  if (error != kvImageNoError) {
    NSLog(@"[VIImage ERROR][No %d]", (int)error);
  }
  
  return vimage;
}

```
#GPUImagePicture(GPUImage) - UIImage
```objc:gpuimagepicture-uiimage.m
//uiimageからgpuimagepicture
GPUImagePicture *gpuImage = [[GPUImagePicture alloc] initWithImage:uiimage];

//gpuimagepictureからuiimage(GPUImageFilterを通す)
GPUImageFilter *filter = /*GPUImgeFilterを継承しているなにかしら*/
[gpuImage addTarget:filter];
[filter useNextFrameForImageCapture];
[gpuImage processImage];
UIImage *dstuiimage = [filter imageFromCurrentFramebuffer];
```

#cv::Mat(OpenCV) - UIImage
```objc:cvmat-uiimage.m

#import "opencv2/imgcodecs/ios.h"

//uiimageからcv::Mat
cv::Mat cvmat;
UIImageToMat(uiimage, cvmat);

//cv::Matからuiimage
UIImage *uiimage = MatToUIImage(cvmat);
```

#(オマケ)opencvで画像処理するときのテンプレート
```objc:UtilOpenCVHelper.h

#ifndef UtilOpenCVHelper_h
#define UtilOpenCVHelper_h

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface UtilOpenCVHelper : NSObject
+(UIImage *)testOpenCVMethodWithUIImage:(UIImage *)image;
@end

```

```objc:UtilOpenCVHelper.mm
#import "UtilOpenCVHelper.h"
#import "opencv2/imgcodecs/ios.h"

@interface UtilOpenCVHelper()
@end

@implementation UtilOpenCVHelper

typedef BOOL (^openCVAlgorithm)(const cv::Mat&, cv::Mat&) ;

//UIImageをopencvで処理してUIImageで返すテンプレート
+(UIImage *)template:(UIImage *)uiimage withAlgorithm:(openCVAlgorithm)algorithm{
  cv::Mat cvmat;
  UIImageToMat(uiimage, cvmat);
  
  UIImage *dstuiimage = uiimage;
  
  cv::Mat cvdstmat;

  if(algorithm(cvmat, cvdstmat)){
    dstuiimage = MatToUIImage(cvdstmat);
  }
  else{
    NSLog(@"[OPENCV ERROR]");
  }
  
  return dstuiimage;
}

//実際にOpenCVで処理する部分
+(UIImage *)testOpenCVMethodWithUIImage:(UIImage *)image{
  return [UtilOpenCVHelper template:image
          withAlgorithm:^BOOL (const cv::Mat &cvmat, cv::Mat &cvdstmat){
    /*
       opencvで画像処理
       cvdstmatが出力
     */
    return ! cvdstmat.empty()
  }];
}
```


```