Well, I see I have a huge memory leak in CIImage.
However, I don't see where my code is in error.
Also, according to Instruments Object Allocation, ImageIO is holding this memory.
So I guess Core Image calls IImageIO.
I'll have to look at this in more detail.

Jim Merkel

On Jul 25, 2011, at 3:58 PM, Mike Abdullah wrote:


On 25 Jul 2011, at 20:04, James Merkel wrote:

What is the fastest way to generate and display a thumbnail from a digital camera file? In the past I used NSImage -- however the quality (with JPEG files) leaves something to be desired. Now I am using CIImage with Lanczos scale transform -- quality is very good but it is slow (particularly with raw files).

Lanczos is high quality and slow, no way around that.

Should I be using the thumbnail capability of Image I/O? Will it have as good a quality as CIImage, but be faster?

Yes, you should be using it. It won't be as high quality as CIImage though.

I am comparing the speed of my app (running in Xcode) with the speed of Preview. Preview is much faster ( 2x or 3X). I wonder what they are doing.

Of course the fastest way to display a thumbnail is to use the thumbnail in the file (assuming there is one). But that's the problem, there may not be a thumbnail in the file, in which case you need to create one yourself.

That's exactly what ImageIO offers you; the ability to use embedded thumbnail if present.


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