Re: Saving the result of processing an image to another image

Subject: Re: Saving the result of processing an image to another image

From: Pierre-Olivier Latour <email@hidden>

Date: Fri, 6 May 2005 13:22:42 -0700

Delivered-to: email@hidden

Then, I create a QCView, sized to the desired output image size. I set the content view of my offscreen window to be my QCView.

Next, you'd hook up your image object to the view, something like this:

success = [myQCView setValue:myImage forInputKey:@"Image"];

Now you are ready to "run" the composition.

BOOL started = [myQCView startRendering];

That's enough to make it generate its first frame, which, if you're using QC for still images, is enough. It's time to get the output image.

image = [myQCView valueForOutputKey:@"Image"]; // image with NSCGImageRep

Then, you can stop rendering: [myQCView stopRendering];

What's you describe here works, although it could be a lot more optimized: using a QCRenderer instead of a QCView and not do start / render / stop for every frame as it prevents any caching of resources.

In your current implementation, you might not even need to create a background window, just the QCView. Or even better, something like this might work:

NSString* compositionPath = @"?"; //Set to composition path

NSOpenGLPixelFormatAttribute attributes[] = {NSOpenGLPFAAccelerated, NSOpenGLPFANoRecovery, (NSOpenGLPixelFormatAttribute)0};

NSAutoreleasePool* pool = [NSAutoreleasePool new];

NSOpenGLPixelFormat* format = [[NSOpenGLPixelFormat alloc] initWithAttributes:attributes];

NSOpenGLContext* context = [[NSOpenGLContext alloc] initWithFormat:format shareContext:nil];

QCRenderer* renderer = [[QCRenderer alloc] initWithOpenGLContext:context pixelFormat:format file:compositionPath];

//Do the following for each image to be processed by the composition

{

//Set composition input parameters here - like numerical values, images...

//[renderer setValue:? forInputKey:@"Image"];

//Run composition

[renderer renderAtTime:0.0 arguments:nil];

//Retrieve composition output results here

//image = [renderer valueForOutputKey:@"Image"];

}

[renderer release];

[context release];

[format release];

[pool release];

________________________________________________________

Pierre-Olivier Latour email@hidden

Quartz Composer Architect Graphic & Imaging Team

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References:
	>Saving the result of processing an image to another image (From: Benoit Marchant <email@hidden>)
	>Re: Saving the result of processing an image to another image (From: Dan Wood - Discussion Lists <email@hidden>)