Good morning!

I studied how to get a pixel data information from a image.

But I couldn't understand most it, because it's difficulty  complication and difficulty.

actually, I don't need this skill. But I need it when I extend my application "YubiFude".

In other words, I can' t extend if I solved it.

I tried solve a this code↓↓↓(included my comment)

"Returns a read-only pointer to the bytes of a CFData object."

I'll confer together

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- (void)imagePickerController:(UIImagePickerController*)picker 
  didFinishPickingImage:(UIImage*)image 
                 editingInfo:(NSDictionary*)editingInfo
{

    NSLog(@"editingInfo:%@",editingInfo);
    // UIImagePickerControllerCropRect = NSRect: {{0, 0}, {640, 425}};
  // UIImagePickerControllerOriginalImage = ;

    statusButton.hidden = NO;
    colorButton.hidden = NO;
    fillColorButton.hidden = NO;
    doneButton.hidden = NO;
    allClearButton.hidden = NO;
    layer1ClearButton.hidden = NO;
    layer2ClearButton.hidden = NO;
    layer3ClearButton.hidden = NO;
    saveButton.hidden = NO;
    loadButton.hidden = NO;
    
  // イメージピッカーを隠す
  [self dismissModalViewControllerAnimated:YES];
   
  // オリジナル画像を取得する
  UIImage* originalImage;
  originalImage = [editingInfo objectForKey:UIImagePickerControllerOriginalImage];
   
  // グラフィックスコンテキストを作る、小さくすると無理に引き延ばすのでモザイクがかかる
  CGSize size = { 320, 480 };
  UIGraphicsBeginImageContext(size);
    //Creates a bitmap-based graphics context and makes it the current context.
    

   
  // 表示する画像のサイズ
  CGRect rect;
  rect.origin = CGPointZero;//(0, 0)
  rect.size = size;
  [originalImage drawInRect:rect];
    
  // 描画した画像を取得する
  shrinkedImage = UIGraphicsGetImageFromCurrentImageContext();
    //Returns an image based on the contents of the current bitmap-based graphics context.
    

  UIGraphicsEndImageContext();
  //Removes the current bitmap-based graphics context from the top of the stack.
    

  // CGImageを取得する
  CGImageRef cgImage;
  cgImage = shrinkedImage.CGImage;
   
  // 画像情報を取得する
    //typedef __SIZE_TYPE__        __darwin_size_t;    /* sizeof() */
    //typedef __darwin_size_t        size_t;
  size_t width;//320
  size_t height;//480
  size_t bitsPerComponent;//8
  size_t bitsPerPixel;//32
  size_t bytesPerRow;//1280 = 4byte*320
  CGColorSpaceRef colorSpace;
  CGBitmapInfo bitmapInfo;//8193
  bool shouldInterpolate;//true
  CGColorRenderingIntent intent;//14081600
  width = CGImageGetWidth(cgImage);
  height = CGImageGetHeight(cgImage);
  bitsPerComponent = CGImageGetBitsPerComponent(cgImage);
  bitsPerPixel = CGImageGetBitsPerPixel(cgImage);
  bytesPerRow = CGImageGetBytesPerRow(cgImage);
  colorSpace = CGImageGetColorSpace(cgImage);
  bitmapInfo = CGImageGetBitmapInfo(cgImage);
  shouldInterpolate = CGImageGetShouldInterpolate(cgImage);//Returns the interpolation setting for a bitmap image.
  intent = CGImageGetRenderingIntent(cgImage);//Returns the rendering intent setting for a bitmap image.
                                                /*kCGRenderingIntentDefault,
                                                 kCGRenderingIntentAbsoluteColorimetric,
                                                 kCGRenderingIntentRelativeColorimetric,
                                                 kCGRenderingIntentPerceptual,
                                                 kCGRenderingIntentSaturation*/
  // データプロバイダを取得する
  CGDataProviderRef dataProvider;// which you use to move data into and out of Quartz. 
                                     // CGDataProviderRef allow you to supply Quartz functions with data.
  dataProvider = CGImageGetDataProvider(cgImage);//Returns the data provider for a bitmap image.
    

   
  // ビットマップデータを取得する
  CFDataRef data;
    //A reference to an immutable CFData object.
  UInt8* buffer;
    //typedef unsigned char UInt8;

  data = CGDataProviderCopyData(dataProvider);//data = 614400byte = 153600(320*480)*4
    //Returns a copy of the provider’s data.
    

  buffer = (UInt8*)CFDataGetBytePtr(data);
    //Returns a read-only pointer to the bytes of a CFData object.
  // ビットマップに効果を与える
     NSUInteger i, j;
     for (j = 0; j < height; j++)
     {
         for (i = 0; i < width; i++) 
         {
             // ピクセルのポインタを取得する
             UInt8* tmp;
             tmp = buffer + j * bytesPerRow + i * 4;
             //
             //NSLog(@"tmp:%d",tmp);
            // NSLog(@"buffer : %d",buffer);
             //NSLog(@"buffer : %d",&buffer);

             // RGBの値を取得する
             UInt8 r, g, b;
             r = *(tmp + 3);//b
             g = *(tmp + 2);//g
             b = *(tmp + 1);//r
        //     NSLog(@"\nr:%d\ng;%d\nb:%d",r,g,b);

     
             // 輝度値を計算する
             UInt8 y;
             y = (77 * r + 28 * g + 151 * b) / 256;//重み付きの平均値
            /* この重み付きの平均値 gray は輝度と呼ばれるもので、カラーテレビの信号処理
             に使われます。輝度は色の明るさを表します。
             　重みを付けて平均を取るのは、人の視覚は赤・緑・青に対してそれぞれ感度が異
             なるためで、
             
             　　　　青 < 赤 < 緑
             
             の順に感度が高くなります。最も感度の高い色に重みを持たせています。
             http://www.asahi-net.or.jp/~uc3k-ymd/Glib32/loadbmp.html*/
     
             // 輝度の値をRGB値として設定する
             *(tmp + 1) = y;//b
             *(tmp + 2) = y;//g
             *(tmp + 3) = y;//r
         }
    }
     
  // 効果を与えたデータを作成する
  CFDataRef effectedData;
  effectedData = CFDataCreate(NULL, buffer, CFDataGetLength(data));
   
  // 効果を与えたデータプロバイダを作成する
  CGDataProviderRef effectedDataProvider;
  effectedDataProvider = CGDataProviderCreateWithCFData(effectedData);
   
  // 画像を作成する
    // UIImage* effectedImage;
  effectedCgImage = CGImageCreate(
                                    width, height, 
                                    bitsPerComponent, bitsPerPixel, bytesPerRow, 
                                    colorSpace, bitmapInfo, effectedDataProvider, 
                                    NULL, shouldInterpolate, intent);
    //Creates a bitmap image from data supplied by a data provider.
    /*size_t width,
    size_t height,
    size_t bitsPerComponent,
    size_t bitsPerPixel,
    size_t bytesPerRow,
    CGColorSpaceRef colorspace,
    CGBitmapInfo bitmapInfo,
    CGDataProviderRef provider,
    const CGFloat decode[],
    bool shouldInterpolate,
    CGColorRenderingIntent intent
    );*/
    // effectedImage = [[UIImage alloc] initWithCGImage:effectedCgImage];
    // [effectedImage autorelease];
   
  // 画像を表示する
    // _imageView.image = effectedImage;

  [PaintingView loadImage];
  // 作成したデータを解放する
  CGImageRelease(effectedCgImage);
  CFRelease(effectedDataProvider);
  CFRelease(effectedData);
  CFRelease(data);
    [[UIApplication sharedApplication] setStatusBarHidden:YES];

    self.navigationController.navigationBarHidden = YES;
}

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This code is invoked when pushed UIImagePickerController's choose button.

I could understand theacceptation most of code.But  I didn't understand this code 

  buffer = (UInt8*)CFDataGetBytePtr(data);

,,,,,,what isCFDataGetBytePtr??

According to reference,,,

"Returns a read-only pointer to the bytes of a CFData object."

I'll talk to my togeher about this code at tomorrow.

And I don't complete the concept the "pointer".

I'll talk to teacher about it too.

I'd like to complete it tommorow.

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"We have only more 12 days to go before the deadline."

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