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将NSImage转换为CIImage而不降低质量

core-image cocoa objective-c

2

David · 技术社区 · 15 年前

我正在尝试将NSImage转换为CIImage。当我这样做的时候,图像质量似乎有很大的损失。我认为这是因为“代表性”。有人有更好的方法吗?谢谢。

NSImage *image = [[NSImage alloc] initWithData:[someSource dataRepresentation]];

NSData  * tiffData = [image TIFFRepresentation];
CIImage *backgroundCIImage = [[CIImage alloc] initWithData:tiffData];

CIContext *ciContext = [[NSGraphicsContext currentContext] CIContext];  
[ciContext drawImage:backgroundCIImage atPoint:CGPointZero fromRect:someRect];

3 回复 | 直到 15 年前

1

Chuck 15 年前

你的问题确实是转化成了TIFF。PDF是矢量格式,而TIFF是位图格式,因此TIFF在较大的尺寸下看起来会很模糊。

2

0

AlcubierreDrive 15 年前

试着更换线路

NSData  * tiffData = [image TIFFRepresentation];

具有

NSData  * tiffData = [image TIFFRepresentationUsingCompression: NSTIFFCompressionNone factor: 0.0f];

the documentation 说明TIFF表示使用与每个图像表示关联的TIFF压缩选项,该选项可能不是NSTIFFCompressionNone。因此,您应该明确表示希望数据未压缩。

3

0

David 15 年前

    NSImage *pdfImage = [[NSImage alloc] initWithData:[[aPDFView activePage] dataRepresentation]];
    NSSize size = [pdfImage size];
    NSRect imageRect = NSMakeRect(0, 0, size.width, size.height);
    imageRect.size.width *= 2; //Twice the scale factor
    imageRect.size.height *= 2; //Twice the scale factor

    PDFDocument *pageDocument = [[[PDFDocument alloc] init] autorelease];
    [pageDocument insertPage:[aPDFView activePage] atIndex:0];

    PDFView *pageView = [[[PDFView alloc] init] autorelease];
    [pageView setDocument:pageDocument];
    [pageView setAutoScales:YES];

    NSWindow *offscreenWindow = [[NSWindow alloc] initWithContentRect:imageRect 
                                                            styleMask:NSBorderlessWindowMask
                                                              backing:NSBackingStoreRetained
                                                                defer:NO];

    [offscreenWindow setContentView:pageView];
    [offscreenWindow display];
    [[offscreenWindow contentView] display]; // Draw to the backing buffer

    // Create the NSBitmapImageRep
    [[offscreenWindow contentView] lockFocus];

    NSBitmapImageRep* rep = [[NSBitmapImageRep alloc] initWithFocusedViewRect:imageRect];

    // Clean up and delete the window, which is no longer needed.
    [[offscreenWindow contentView] unlockFocus];

    [compositeImage TIFFRepresentation]];
    NSData *imageData = [rep representationUsingType: NSJPEGFileType properties: nil];
    [imageData writeToFile:@"/Users/David/Desktop/out.jpg" atomically: YES];

    [offscreenWindow release];