ApplyBlurWithRadius works on iPhone 6, not 6+ (UIImage + ImageEffects)
I'm using Apple UIImage+ImageEffects
from WWDC (2013?)
This method works great on iPhone 6, but produces a really weird jagged, oversaturated image on iPhone 6 Plus:
[self applyBlurWithRadius:60 tintColor:[UIColor colorWithWhite:1.0 alpha:0.3] saturationDeltaFactor:2.4 maskImage:nil];
iPhone 6 (correct):
iPhone 6 Plus (weird):
Any idea what's going on?
Update: I determined through trial and error that setting blurRadius to anything less than or equal to 50 shows OK, so it is related to radius. I would still like to know what exactly makes it peek at the big screen.
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I know this question is old and the OP has moved on since then, but I would like to explain why it is different on every phone ... for future generations.
iPhone6 and iPhone6 + have different screen resolutions. Basically, the iPhone6 has a scale of 2.0, while the iPhone6 + has a scale of 3.0.
Why does it matter?
In the source code applyBlurWithRadius
in the source file UIImage+ImageEffects.m
you will find the following lines:
CGFloat inputRadius = blurRadius * [[UIScreen mainScreen] scale];
uint32_t radius = floor(inputRadius * 3. * sqrt(2 * M_PI) / 4 + 0.5);
if (radius % 2 != 1) {
radius += 1; // force radius to be odd so that the three box-blur methodology works.
}
You can see what inputRadius
will differ depending on the screen scale. So on iPhone6 this value will be 60*2
(end result for radius
will be: 227), and on iPhone6 + the value will be 60*3
(end result for radius
will be 339). This will obviously lead to different results as they are different values.
What about the color difference? I'm pretty sure I radius
shouldn't exceed 255, otherwise undefined results might occur (possibly an integer overflow causing color components to zero to zero). Since the iPhone6 + screen scale value pushes it above this value, you see strange results, but not on the iPhone6 as it is below this threshold.
You should see the same weirdness on iPhone6 using 90 for the parameter blurRadius
.
Side note: you don't need values higher than 30 for the parameter anyway blurRadius
- the results won't be much different from that point.
Hope this helps you.
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