Comments on: How to Mask an Image

By: Christoph B

Christoph B — Fri, 20 Aug 2010 16:24:46 +0000

A shame, I thought I got rid of the black border, then I built it to the device and back there it was. :(

Any ideas?

Cheers,
Christoph

By: Brandon

Brandon — Tue, 10 Aug 2010 16:20:32 +0000

In addition to Jean and Xavier’s code, I have added one more condition for the alpha channel check:

if ((CGImageGetAlphaInfo(sourceImage) == kCGImageAlphaNone)
|| (CGImageGetAlphaInfo(sourceImage) == kCGImageAlphaNoneSkipFirst)
|| (CGImageGetAlphaInfo(sourceImage) == kCGImageAlphaNoneSkipLast)) {
imageWithAlpha = CopyImageAndAddAlphaChannel(sourceImage);
}

By: Forrest

Forrest — Sat, 17 Jul 2010 05:32:25 +0000

question about how to creating mask image with programming way :

as we know, we can create such mask image via loading or reading one mask image edited already.

but what I want now is to create those data via some codes, just like GDI+ does, any clues ?

thanks

By: nishant

nishant — Thu, 24 Jun 2010 12:48:16 +0000

Thank’s Rodney, this really helps perfect, which i am looking for! Thanks again!

By: MN

MN — Thu, 27 May 2010 09:45:58 +0000

Can we use CGImageCreateCopyWithColorSpace(maskref,CGColorSpaceCreateDeviceGray()) instead of CGImageMaskCreate(All the parameters and separate method calls)?

By: Casey

Casey — Tue, 18 May 2010 07:44:17 +0000

SOLUTION!!

Ok, this is stupidly easy to do after figuring out. The main problem is the mask image but after hours of banging my head on my desk I figured it out. Use whatever software you wish to create the mask.png with whatever colors you want and save it. The trick is to open it in Preview, yes Preview and click Save As, DESELECT the Alpha button and save. Your mask is now finished.

-(UIImage*)maskImage:(UIImage*)image withMask:(UIImage*)mask {

CGImageRef imgRef = [image CGImage];
CGImageRef maskRef = [mask CGImage];
CGImageRef actualMask = CGImageMaskCreate(CGImageGetWidth(maskRef),
CGImageGetHeight(maskRef),
CGImageGetBitsPerComponent(maskRef),
CGImageGetBitsPerPixel(maskRef),
CGImageGetBytesPerRow(maskRef),
CGImageGetDataProvider(maskRef), NULL, false);

CGImageRef masked = CGImageCreateWithMask(imgRef, actualMask);

return [UIImage imageWithCGImage:masked];

}

By: John

John — Sun, 28 Feb 2010 18:59:10 +0000

The code looks great, and I have made my mask.png file

However, where should I insert the code? My gues is system/library/coreservices/springboard.app/info.plist but I’m not sure.

Also, would it automatically apply the mask to all apps? Thanks.

By: ryemac3

ryemac3 — Sun, 21 Feb 2010 22:57:45 +0000

So how do you can this method? Say your imageview is populated by the ‘didFinishPickingMediaWithInfo” method, how would you mask the results? Do you just add this code to the “didFinishPickingMediaWithInfo” method?

By: Jacob

Jacob — Fri, 15 Jan 2010 16:18:46 +0000

Great tips! I’m having a bit of trouble though. I have a mask of a set size (100×100). I want to use this small mask on larger images of various sizes (320×480, 600×900, etc). However, my mask is stretching to the size of the image. Any ideas on how to maintain a smaller mask?

Thanks!

By: Amit

Amit — Mon, 28 Dec 2009 06:05:59 +0000

Hi ,

I am new to iphone development and dont know how to implement this concept in xcode for iphone ,can anybody please provide me the whole source code or sample project for image masking with image.

Thanks in Advance…