CODEWITHSUNDEEP
ioscocoa-touchuiimage
the Reverend
the Reverend

Reputation: 12549

UIImage size in pixels

Can I get the pixel size for a UIImage if I just multiply the image.size with the image.scale ? Is it the same as doing this:

   guard let cgImage = image.CGImage else{
        return nil
    }
    let width = CGImageGetWidth(cgImage)
    let height = CGImageGetHeight(cgImage)

Upvotes: 10

Views: 7922

Answers (3)

oscarr
oscarr

Reputation: 529

extension UIImage {
    func imageSizeInPixel() -> CGSize {
        let heightInPoints = size.height
        let heightInPixels = heightInPoints * scale

        let widthInPoints = size.width
        let widthInPixels = widthInPoints * scale

        return CGSize(width: widthInPixels, height: heightInPixels)
    }
}

Upvotes: 1

Bartholomew Furrow
Bartholomew Furrow

Reputation: 689

You can, but it isn't the same as cgImage.width x cgImage.height (the new names for the CG functions you gave). The cgImage doesn't know about at least some EXIF flags that might have rotated or flipped the original image. You can see a difference in image Portrait_5.jpg through Portrait_8.jpg at https://github.com/recurser/exif-orientation-examples. image.size.height * image.scale gives 1800, but cgImage.height gives 1200 (really the width).

Upvotes: 6

rmaddy
rmaddy

Reputation: 318794

Yes.

CGImageGetWidth and CGImageGetHeight will return the same size (in pixels) as returned by image.size * image.scale.

Upvotes: 14

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