こんにちは、読んでくれてありがとう！ディスク上のファイルに NSImage オブジェクトを書き込もうとしていますが、元の NSImage から NSData オブジェクトを抽出するときに「イメージ プロパティ」の一部が失われるため、問題が発生しています。
問題を説明するために、以下のコードがあります。元の NSImage オブジェクトは 'image' と呼ばれ、これを imageDump (最後に出力) に渡します。次に、これから NSData オブジェクトを抽出してファイルに書き込みますが、そうすると画像プロパティの一部が削除されるようです。再び imageDump を呼び出します (最後に再度出力します) が、今回はいくつかのプロパティがどのように削除されたかに注意してください。たとえば、CGImageGetBitsPerPixel: は 32 から始まりますが、imageDump の 2 回目の呼び出しでは 24 になっていますか?
ディスクに書き込む前に NSData オブジェクトを抽出するときに、これらのイメージ プロパティが削除されないようにするにはどうすればよいですか?
NSLog(@"/n PRINTING THE IMAGE PASSED TO THIS METHOD\n");
[self imageDump:[image CGImageForProposedRect:NULL context:NULL hints:NULL]];
NSData *imageData = [image TIFFRepresentation];
NSImage *montysImage = [[NSImage alloc ] initWithData:imageData];
NSLog(@"/n PRINTING THE IMAGE THAT WAS FIRST CONVERTED TO NSDATA AND THEN BACK\n");
[self imageDump:[montysImage CGImageForProposedRect:NULL context:NULL hints:NULL]];
-(void)imageDump:(CGImageRef)cgimage {
size_t width = CGImageGetWidth(cgimage);
size_t height = CGImageGetHeight(cgimage);
size_t bpr = CGImageGetBytesPerRow(cgimage);
size_t bpp = CGImageGetBitsPerPixel(cgimage);
size_t bpc = CGImageGetBitsPerComponent(cgimage);
size_t bytes_per_pixel = bpp / bpc;
CGBitmapInfo info = CGImageGetBitmapInfo(cgimage);
NSString *file = @"file";
NSLog(
@"\n"
"===== %@ =====\n"
"CGImageGetHeight: %d\n"
"CGImageGetWidth: %d\n"
"CGImageGetColorSpace: %@\n"
"CGImageGetBitsPerPixel: %d\n"
"CGImageGetBitsPerComponent: %d\n"
"CGImageGetBytesPerRow: %d\n"
"CGImageGetBitmapInfo: 0x%.8X\n"
" kCGBitmapAlphaInfoMask = %s\n"
" kCGBitmapFloatComponents = %s\n"
" kCGBitmapByteOrderMask = %s\n"
" kCGBitmapByteOrderDefault = %s\n"
" kCGBitmapByteOrder16Little = %s\n"
" kCGBitmapByteOrder32Little = %s\n"
" kCGBitmapByteOrder16Big = %s\n"
" kCGBitmapByteOrder32Big = %s\n",
file,
(int)width,
(int)height,
CGImageGetColorSpace(cgimage),
(int)bpp,
(int)bpc,
(int)bpr,
(unsigned)info,
(info & kCGBitmapAlphaInfoMask) ? "YES" : "NO",
(info & kCGBitmapFloatComponents) ? "YES" : "NO",
(info & kCGBitmapByteOrderMask) ? "YES" : "NO",
(info & kCGBitmapByteOrderDefault) ? "YES" : "NO",
(info & kCGBitmapByteOrder16Little) ? "YES" : "NO",
(info & kCGBitmapByteOrder32Little) ? "YES" : "NO",
(info & kCGBitmapByteOrder16Big) ? "YES" : "NO",
(info & kCGBitmapByteOrder32Big) ? "YES" : "NO" );
CGDataProviderRef provider = CGImageGetDataProvider(cgimage);
NSData* data = (__bridge id)CGDataProviderCopyData(provider);
//[data autorelease];
const uint8_t* bytes = [data bytes];
printf("Pixel Data:\n");
for(size_t row = 0; row < height; row++)
{
for(size_t col = 0; col < width; col++)
{
const uint8_t* pixel = &bytes[row * bpr + col * bytes_per_pixel];
printf("(");
for(size_t x = 0; x < 3; x++) // 3 WAS -> bytes_per_pixel - changed to remove the alpha component.
{
printf("%.2X", pixel[x]);
if( x < 3 - 1 ) // 3 WAS -> bytes_per_pixel - changed to remove the alpha component.
printf(",");
}
printf(")");
if( col < width - 1 )
printf(", ");
}
printf("\n");
}
}
コンソール出力:
2013-11-06 22:52:01.082 LibraryBuilder[20792:303] /n PRINTING THE IMAGE PASSED TO THIS METHOD 2013-11-06 22:52:01.082 LibraryBuilder[20792:303] ===== file ===== CGImageGetHeight: 6 CGImageGetWidth: 7 CGImageGetColorSpace: <CGColorSpace 0x60000003b840> (kCGColorSpaceICCBased; kCGColorSpaceModelRGB; Color LCD) CGImageGetBitsPerPixel: 32 CGImageGetBitsPerComponent: 8 CGImageGetBytesPerRow: 64 CGImageGetBitmapInfo: 0x00002006 kCGBitmapAlphaInfoMask = YES kCGBitmapFloatComponents = NO kCGBitmapByteOrderMask = YES kCGBitmapByteOrderDefault = NO kCGBitmapByteOrder16Little = NO kCGBitmapByteOrder32Little = YES kCGBitmapByteOrder16Big = YES kCGBitmapByteOrder32Big = NO Pixel Data: (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (EA,D9,C2) (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7) (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7) (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7) (B3,B3,B3), (B3,B3,B3), (B3,B3,B3), (B3,B3,B3), (B3,B3,B3), (B3,B3,B3) (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7) (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7) 2013-11-06 22:52:01.122 LibraryBuilder[20792:303] /n PRINTING THE IMAGE THAT WAS FIRST CONVERTED TO NSDATA AND THEN BACK 2013-11-06 22:52:01.122 LibraryBuilder[20792:303] ===== file ===== CGImageGetHeight: 6 CGImageGetWidth: 7 CGImageGetColorSpace: <CGColorSpace 0x618000032f40> (kCGColorSpaceICCBased; kCGColorSpaceModelRGB; Color LCD) CGImageGetBitsPerPixel: 24 CGImageGetBitsPerComponent: 8 CGImageGetBytesPerRow: 18 CGImageGetBitmapInfo: 0x00000000 kCGBitmapAlphaInfoMask = NO kCGBitmapFloatComponents = NO kCGBitmapByteOrderMask = NO kCGBitmapByteOrderDefault = NO kCGBitmapByteOrder16Little = NO kCGBitmapByteOrder32Little = NO kCGBitmapByteOrder16Big = NO kCGBitmapByteOrder32Big = NO Pixel Data: (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (C2,D9,EA) (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7) (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7) (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7) (B3,B3,B3), (B3,B3,B3), (B3,B3,B3), (B3,B3,B3), (B3,B3,B3), (B3,B3,B3) (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7) (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7), (F7,F7,F7)