Convert FloatArray coming from pytorch Tensor to Bitmap

convertRGB.kt

fun floatArrayToColorBitmap (
    floatArray: FloatArray,
    width: Int,
    height: Int,
    alpha :Byte = (255).toByte(),
    reverseScale :Boolean = false
) : Bitmap {

    // Create empty bitmap in RGBA format (even though it says ARGB but channels are RGBA)
    val bmp = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888)
    val byteBuffer= ByteBuffer.allocate(width*height*4)

    // mapping smallest value to 0 and largest value to 255
    val maxValue = floatArray.max() ?: 1.0f
    val minValue = floatArray.min() ?: 0.0f
    val delta = maxValue-minValue

    // Define if float min..max will be mapped to 0..255 or 255..0
    val conversion = when(reverseScale) {
        false -> { v: Float -> ((v-minValue)/delta*255).toByte() }
        true -> { v: Float -> (255-(v-minValue)/delta*255).toByte() }
    }

    var bitmapCounter = 0
    floatArray.forEach { value ->

        byteBuffer.put(bitmapCounter, conversion(value))
        bitmapCounter++
        // every 4th entry is the alpha value
        if(bitmapCounter%4 == 3) {
            byteBuffer.put(bitmapCounter, alpha)
            bitmapCounter++
        }
    }

    bmp.copyPixelsFromBuffer(byteBuffer)

    return bmp
}