How to create an ARGB8888 Binary image on iOS swift

Question

I am using the following code to create the ARGB8888 image. Is this the correct Image format for ARBG8888 or should I use a different format. This link is used to create the below Image FOrmat

guard let imageConversionToCGImage = img.cgImage,
              let imageFormat = vImage_CGImageFormat(
                bitsPerComponent: 8,
                bitsPerPixel: 32,
                colorSpace: CGColorSpaceCreateDeviceRGB(),
                bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.first.rawValue),
                renderingIntent: .defaultIntent),    
                //Source buffer
                let sourceBuffer = try? vImage_Buffer(cgImage: imageConversionToCGImage, format: imageFormat, flags: .noFlags),
              //ARGBImage
                let argb8888CGImage = try? sourceBuffer.createCGImage(format: imageFormat) else { return } ```

and I am getting the image data using the DataProvider.CFData for getting the data . Is this the right format or am I doing it wrong. What should I do to make it so I get the ARGB data.

Answer 1

When you pass a populated vImage_CGImageFormat to that initializer, vImage will attempt to convert the source image to the specified format. For example, you could pass a grayscale image format such as:

let imageFormat = vImage_CGImageFormat(
    bitsPerComponent: 8,
    bitsPerPixel: 8,
    colorSpace: CGColorSpaceCreateDeviceGray(),
    bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue),
    renderingIntent: .defaultIntent)

And the returned buffer will contain a grayscale representation of the source image regardless of the source image's format.

If you want to populate a buffer based on the format of the source image, pass an empty vImage_CGImageFormat and use the vImageBuffer_InitWithCGImage function:

var imageFormat = vImage_CGImageFormat()
var sourceBuffer = vImage_Buffer()
vImageBuffer_InitWithCGImage(&sourceBuffer,
                             &imageFormat,
                             nil,
                             cgImage,
                             vImage_Flags(kvImageNoFlags))

On return, imageFormat contains the color space and bit depth of the source image, and sourceBuffer contains the image itself.

Apple have just released the vImage.PixelBuffer that provides a Swift friendly API to vImage. Take a look at init(cgImage:cgImageFormat:pixelFormat:).

Finally, init(data:width:height:byteCountPerRow:pixelFormat:) shows an example of creating a vImage pixel buffer from a Core Graphics image's underlying data.