CGImageCreateWithImageInRect not working properly

Question

I am trying to use CGImageCreateWithImageInRect to get a sub-image from an image but it's not working properly. It returns the image from a random place in the image, rather than the one I specify. Please take a look at the following image;

enter image description here

My code is:

CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], CGRectMake(524, 1331, 600, 600));
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);

But that doesn't work. What am I doing wrong?

Thanks!

In addition to @HalR's answer, note that the y axis is flipped in Core Graphics by default, so you probably want y = 0 here. — Ben Zotto, Nov 03 '13 at 19:18

score 6 · Accepted Answer · edited May 23 '17 at 10:29

It is likely that your image has a UIImageOrientation set for it that is different from what you are expecting. The iOS will display the image properly, yet the image will be stored sideways (for lack of a better term).

So when you say give me the rect starting at x, y you will get y, x instead, or some random craziness because you are accessing a rect that is outside of the normal range.

This answer talks about fixing the orientation.

score 2 · Answer 2 · edited May 23 '17 at 12:26

2

please see followed answer, you need transform the rect or transform the image. I prefer to transforming the rect.

https://stackoverflow.com/a/21560825/2482283

edited May 23 '17 at 12:26

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answered Feb 04 '14 at 18:53

andrewchan2022

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CGImageCreateWithImageInRect not working properly

2 Answers2