Convert a Double Array to UIImage in swift

Question

Is it possible to convert a double array to UIImage using UIImage function?

var ImageDouble = [1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0]

UIImage function asks for String. I tried converting the array on individual element to strings and the whole thing to string, I get a nill result. Can someone help?

[Edit:]

As it seems I was not really clear on my problem. To make it more clear, I am developing a software which crops numbers & operators from a mathematical expression and shows me all the chunks one by one. Now, how do I go about it in Swift? :

Step-1: I have a grayscale image provided. I read it using UIImage function. I convert it to a custom RGBA function as follows so that I can deal on a pixel level like we do in MATLAB or Python or C++. The function is inspired from many websites's suggestions to use it.

struct Pixel {
var value: UInt32
var red: UInt8 {
    get { return UInt8(value & 0xFF) }
    set { value = UInt32(newValue) | (value & 0xFFFFFF00) }
}
var green: UInt8 {
    get { return UInt8((value >> 8) & 0xFF) }
    set { value = (UInt32(newValue) << 8) | (value & 0xFFFF00FF) }
}
var blue: UInt8 {
    get { return UInt8((value >> 16) & 0xFF) }
    set { value = (UInt32(newValue) << 16) | (value & 0xFF00FFFF) }
}
var alpha: UInt8 {
    get { return UInt8((value >> 24) & 0xFF) }
    set { value = (UInt32(newValue) << 24) | (value & 0x00FFFFFF) }
}

}

struct RGBA {
var pixels: UnsafeMutableBufferPointer<Pixel>
var width: Int
var height: Int
init?(image: UIImage) {
    guard let cgImage = image.CGImage else { return nil }
    width = Int(image.size.width)
    height = Int(image.size.height)
    let bitsPerComponent = 8
    let bytesPerPixel = 4
    let bytesPerRow = width * bytesPerPixel
    let imageData = UnsafeMutablePointer<Pixel>.alloc(width * height)
    let colorSpace = CGColorSpaceCreateDeviceRGB()
    var bitmapInfo: UInt32 = CGBitmapInfo.ByteOrder32Big.rawValue
    bitmapInfo |= CGImageAlphaInfo.PremultipliedLast.rawValue & CGBitmapInfo.AlphaInfoMask.rawValue
    guard let imageContext = CGBitmapContextCreate(imageData, width, height, bitsPerComponent, bytesPerRow, colorSpace, bitmapInfo) else { return nil }
    CGContextDrawImage(imageContext, CGRect(origin: CGPointZero, size: image.size), cgImage)
    pixels = UnsafeMutableBufferPointer<Pixel>(start: imageData, count: width * height)
}

func toUIImage() -> UIImage? {
    let bitsPerComponent = 8
    let bytesPerPixel = 4
    let bytesPerRow = width * bytesPerPixel
    let colorSpace = CGColorSpaceCreateDeviceRGB()
    var bitmapInfo: UInt32 = CGBitmapInfo.ByteOrder32Big.rawValue
    bitmapInfo |= CGImageAlphaInfo.PremultipliedLast.rawValue & CGBitmapInfo.AlphaInfoMask.rawValue
    let imageContext = CGBitmapContextCreateWithData(pixels.baseAddress, width, height, bitsPerComponent, bytesPerRow, colorSpace, bitmapInfo, nil, nil)
    guard let cgImage = CGBitmapContextCreateImage(imageContext) else {return nil}
    let image = UIImage(CGImage: cgImage)
    return image
}

}

Step-2: Now I take one channel of the image [Red: it does not matter which one I take, since all the channels have same output] and apply my custom median filter of kernel size 5x5.

Step-3: Next, I do the binarization of the image using Nibblack approximation,where I used averaging filter and standard deviation.

Step-4: After that, I used connected component labelling to separate out different connected components of the image.

Step-5: Finally, I need to crop the labelled images and resize it. For cropping from the original image , I know the location by using a smart location algorithm. For resizing, I want to use Core Graphics Resizing filter. However, for that I need to convert my current output [a two-dimensional array or flattened] to UIImage or CGImage.

That's my real question: How do I convert to UIImage or CGImage from two-dimensional array or flattened array which are of type Array<Double> or Array<Int> ?

Answer 1

Try this:

var ImageDouble = [1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0]
let images = ImageDouble.map{ UIImage(named: "\($0)")}

the map function will transform your array to another array.

Answer 2

Just try this:

var str:[String] = [];

for (var i=0;i<ImageDouble.count;i++){
   str.append(String(ImageDouble[i]));
}
print(str)

But why would you pass a String of numbers to an UIImage? Are images in your asset named as numbers?

Answer 3

Looks like you want to render 1, 2, etc into a bitmap.

First you need a function to do that, and then use flatMap on the array of doubles using this. This will ensure you get an array of UIImages in a safe way by filtering if any nil results when we try to create images.

func createNumberImage(number:Double) -> UIImage?{

    //Set a frame that you want.
    let frame = CGRect(x: 0, y: 0, width: 200, height: 200)
    let view = UIView(frame:frame )
    view.backgroundColor = UIColor.redColor()

    let label = UILabel(frame:frame)
    view.addSubview(label)

    label.font  = UIFont.systemFontOfSize(100);
    label.text = String(format: "%.1lf", arguments:[number])
    label.textAlignment = NSTextAlignment.Center
    view

    UIGraphicsBeginImageContext(view.bounds.size);
    view.layer.renderInContext(UIGraphicsGetCurrentContext()!)
    let screenShot = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return screenShot
}

let doubles = [1.0,2.0,3.0,4.0,5.0,6.0,7.0,8.0,9.0]

//Get the array of UIImage objects.  
let images = doubles.flatMap { createNumberImage($0) }

You can use playground to verify this working. Also you might want to set proper background and text colors and font size to suite your requirements.