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@marchinram
Last active January 19, 2022 08:53
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iOS Swift UIImage subscript extension to get pixel color
import UIKit
extension UIImage {
subscript (x: Int, y: Int) -> UIColor? {
guard x >= 0 && x < Int(size.width) && y >= 0 && y < Int(size.height),
let cgImage = cgImage,
let provider = cgImage.dataProvider,
let providerData = provider.data,
let data = CFDataGetBytePtr(providerData) else {
return nil
}
let numberOfComponents = 4
let pixelData = ((Int(size.width) * y) + x) * numberOfComponents
let r = CGFloat(data[pixelData]) / 255.0
let g = CGFloat(data[pixelData + 1]) / 255.0
let b = CGFloat(data[pixelData + 2]) / 255.0
let a = CGFloat(data[pixelData + 3]) / 255.0
return UIColor(red: r, green: g, blue: b, alpha: a)
}
}
@zimingw25
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can this code show the color of the pixel of a image? For example, I have uiImage, and I would like to know the color of the pixel located in [100.100], how to operate?

@pronebird
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This code won't work if image is stored in BGR format.

@eaigner
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eaigner commented Jan 16, 2018

Why are you copying your data? You can get the byte pointer directly from the provider.

@theLeroy
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theLeroy commented Jul 3, 2019

image

Ive got these errors. whats wrong?

@marchinram
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Author

marchinram commented Jul 3, 2019 via email

@aditiswaroop
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I want to extract RGB values for all pixels from a frame captured during ARSession. The CVPixelBufferFormat for that is of type kCVPixelFormatType_420YpCbCr8BiPlanarFullRange. Will this code work for this format type as well?
I am new to Swift, I am having a tough time trying to understand the format types and difference in manipulating them.

@Shiko007
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Doesn't work on black for some reason

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