我有一些在CGImage中采样像素的代码。我采样的图像是完全红色的。当我采样全尺寸图像时，结果颜色都是红色的阴影，但是如果我采样从同一URL创建的缩略图，结果颜色都是黄色的阴影。我从图像本身提取所有常量，所以在这里真的很困惑。

func analayze(imageAtURL url: URL) async throws -> [Color: Int] {
        guard let imgSource = CGImageSourceCreateWithURL(url as CFURL, nil) else {
            throw Error.cantLoadImage(url)
        }
        
        let cgImage: CGImage
        switch optimization {
        case .fullSize:
            guard let img = CGImageSourceCreateImageAtIndex(imgSource, 0, nil) else {
                throw Error.cantInstantiateImage(url)
            }
            cgImage = img
        case let .scale(maxSide):
            let options: [CFString: Any] = [
                kCGImageSourceCreateThumbnailFromImageAlways: true as CFBoolean,
                kCGImageSourceThumbnailMaxPixelSize: maxSide as CFNumber
            ]
            guard let img = CGImageSourceCreateThumbnailAtIndex(imgSource, 0, options as CFDictionary) else {
                throw Error.cantInstantiateImage(url)
            }
            cgImage = img
        default:
            throw Error.unsupportedOptimization(optimization)
        }

        let width = cgImage.width
        let height = cgImage.height

        let bytesPerRow = cgImage.bytesPerRow
        let bytesPerPixel = bytesPerRow / width
        let bitsPerComponent = cgImage.bitsPerComponent
        assert(bitsPerComponent == 8, "Expected 8 bits per component, got \(bitsPerComponent)")

        guard let pixelData = cgImage.dataProvider?.data else {
            throw Error.contextHasNoData
        }

        guard let unsafePointer = CFDataGetBytePtr(pixelData) else {
            throw Error.cantCreatePointer
        }

        let unsafeRawPointer = UnsafeRawPointer(unsafePointer)

        let points = pointsInRect(width: width, height: height)

        @Sendable
        func findClosestColorInTable(for point: DiscretePoint) -> Color? {
            let offset = (point.y * bytesPerRow) + (point.x * bytesPerPixel)
            let red = CGFloat(unsafeRawPointer.load(fromByteOffset: offset, as: UInt8.self)) / 255
            let green = CGFloat(unsafeRawPointer.load(fromByteOffset: offset + 1, as: UInt8.self)) / 255
            let blue = CGFloat(unsafeRawPointer.load(fromByteOffset: offset + 2, as: UInt8.self)) / 255
            let imgColor = Color(r: red, g: green, b: blue)
//            let nearestNeighbor = self.colorTree.nearest(to: imgColor)
//            return nearestNeighbor
            return imgColor
        }

字符串
以下是全尺寸方法的图像和结果：

的数据
对于缩放方法：

的