Binary to image converter in Kotlin

Bin2Img.kt

package com.asdev.bin2img

import java.awt.Color
import java.awt.image.BufferedImage
import java.io.ByteArrayOutputStream
import java.io.File
import java.nio.file.Files
import javax.imageio.ImageIO

/**
 * Created by Asdev on 08/26/16. All rights reserved.
 * Unauthorized copying via any medium is stricitly
 * prohibited.
 *
 * Authored by Shahbaz Momi as part of BinToImg
 * under the package com.asdev.bin2img
 */

fun main(args: Array<String>) {
    if(args[0] == "bin-in") {
        val img = bin2img(Files.readAllBytes(File(args[1]).toPath())!!.toTypedArray())
        ImageIO.write(img, "png", File(args[2]))
    } else if(args[0] == "img-in") {
        val bytes = img2bin(ImageIO.read(File(args[1])))
        Files.write(File(args[2]).toPath()!!, bytes.toByteArray())
    }
}

fun bin2img(data: Array<Byte>): BufferedImage {
    println("SIZE: " + data.size)
    // compute optimal width and height
    val sqrt = Math.sqrt(data.size.toDouble() / 3.0)
    // add some and call it a day
    val width = sqrt.toInt()
    var height = sqrt.toInt()
    // make sure it fits
    while (width * height < data.size / 3.0) {
        height ++
    }
    println("WIDTH $width HEIGHT $height")
    // convert the data byte to pixel data
    val out = BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR)

    var index = 0
    for(y in 0 until height) {
        for(x in 0 until width) {
            // value index..index + 2
            out.setRGB(x, y, Color(data.getOrElse(index){-128}.toInt() + 128, data.getOrElse(index + 1){-128}.toInt() + 128, data.getOrElse(index + 2){-128}.toInt() + 128).rgb)
            index += 3
            if(index >= data.size) {
                // realign to last three bytes
                index -=3

                // add marker bit
                out.setRGB(x + 1, y, Color( if(index < data.size) 255 else 0, if(index + 1 < data.size) 255 else 0, if(index + 2 < data.size) 255 else 0 ).rgb)
                break
            }
        }
    }

    // set last 3 bytes to 255
    return out
}

fun img2bin(img: BufferedImage): Array<Byte> {
    // get size of data
    var size = img.width * img.height
    // start from end and read all black pixels
    for(x in img.width - 1 downTo 0) {
        // if black, continue
        if(img.getRGB(x, img.height - 1) == Color.BLACK.rgb) {
            size --
        } else {
            // not black no more
            // sub this bit from the size
            size --
            // three bytes per color
            size *= 3
            // this color tells which bits of last is legit
            val lC = Color(img.getRGB(x, img.height - 1))
            // see if there is an actual blue component
            if(lC.blue == 0)
                size --
            // see if there is an actual red component
            if(lC.green == 0)
                size --

            break
        }
    }

    println("DECODE SIZE: $size")

    val output = ByteArrayOutputStream(size)

    var index = 0
    for(y in 0 until img.height) {
        for(x in 0 until img.width) {
            val c = Color(img.getRGB(x, y))
            if(index < size) {
                output.write(c.red - 128)
            }

            if(index + 1 < size) {
                output.write(c.green - 128)
            }

            if(index + 2 < size) {
                output.write(c.blue - 128)
            }

            index += 3
            if(index >= size) {
                break
            }
        }
    }

    return output.toByteArray().toTypedArray()
}