Re: Smoothly decimating UIImageView images
Re: Smoothly decimating UIImageView images
- Subject: Re: Smoothly decimating UIImageView images
- From: Matt Neuburg <email@hidden>
- Date: Fri, 4 Feb 2011 07:29:52 -0800
On Thu, 3 Feb 2011 12:06:25 -0800, Rick Mann <email@hidden> said:
>I'm doing a photo browser of sorts, as part of a larger app. We display a few thumbnails, and if the user taps one, they're presented with the full-size image.
>
>The problem is that I start with the large images, and when I set them on the small UIImageView, they're scaled down and look pretty bad. I have access to a better thumbnail-size version of the image, but that complicates the code to display them.
>
>I don't see any way of changing the decimation algorithm on UIImageView or UIImage, but I did find the minificationFilter on CALayer. Changing that setting on the UIImageView had no effect. I also tried different minificationFilterBias values, to no effect.
I don't know the answer to your question, but my feeling is that you shouldn't "show the large image on a small UIImageView": you should obtain a scaled image and show that. My understanding is that even if the image view is small, it must maintain the image you give it. Maintaining the memory for several large images can make your app less responsive or even kill it. If I'm wrong someone will correct me, but that's the impression I got from at least two different WWDC 2010 videos.
I haven't used the minification filter, but I'm not surprised that changing it had no effect, since this is a layer property, and you are not shrinking the layer.
My impulse, therefore, is to say: don't be lazy, use a thumbnail-size version of the image, even if that "complicates the code".
m.
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