Led Matrix 8x8 to Base64

MatrixToBase64.kt

import java.awt.Color
import java.io.File
import java.util.*
import javax.imageio.ImageIO
import kotlin.system.exitProcess

fun main(args: Array<String>) {
    if (args.isEmpty()) {
        printHelp()
        exitProcess(0)
    }
    val filename = args[0]
    val file = File(filename)
    if (!file.exists()) {
        System.err.println("File does not exist")
        exitProcess(-1)
    }
    if (!file.canRead()) {
        System.err.println("Can't read file")
        exitProcess(-1)
    }
    if (file.isDirectory) {
        file.listFiles().forEach { someFile ->
            val leds = parseFile(someFile)
            leds?.let {
                val base64 = ledsToBase64(leds)
                println(someFile.name)
                println(base64)
            }
        }
    } else {
        val leds = parseFile(File(filename))
        leds?.let {
            val sourceCode = ledsToSourcecode(leds)
            //println(sourceCode)
            val base64 = ledsToBase64(leds)
            println(base64)
        }
    }
}

fun printHelp() {
    print(
        """
        usage: matrix <FILE>
        Transform png image to bytes for arduino
        Needs to be 8x8 rgb png no transparency
    """.trimIndent()
    )
}

fun ledsToSourcecode(leds: List<CRGB>): String {
    val sb = StringBuilder()
    for (i in 0..63) {
        val led = leds[i]
        sb.append("  leds[$i] = CRGB(${led.r},${led.g},${led.b});\n")
    }
    return sb.toString()
}

fun ledsToBase64(leds: List<CRGB>): String {
    val bytes = mutableListOf<Byte>()
    for (i in 0..63) {
        val led = leds[i]
        bytes.add(led.r.toByte())
        bytes.add(led.g.toByte())
        bytes.add(led.b.toByte())
    }
    val byteArray = bytes.toByteArray()
    val base64String = Base64.getEncoder().encodeToString(byteArray)
    return base64String
}

fun parseFile(file: File): List<CRGB>? {
    val bufferedImage = ImageIO.read(file) ?: return null
    val leds = mutableListOf<CRGB>()
    //fill with black
    for (ii in 1..64) {
        leds.add(CRGB(0, 0, 0))
    }
    for (y in 0..7) {
        for (x in 0..7) {
            val rgbInt = bufferedImage.getRGB(x, y)
            val color = Color(rgbInt)
            leds[xy(x, y)].r = color.red
            leds[xy(x, y)].g = color.green
            leds[xy(x, y)].b = color.blue
        }
    }
    return leds
}

fun xy(x: Int, y: Int): Int {
    val MATRIX_WIDTH = 8
    val i = if ((y and 0x01 == 1)) {
        // Odd rows run backwards
        val reverseX: Int = MATRIX_WIDTH - 1 - x
        y * MATRIX_WIDTH + reverseX
    } else {
        // Even rows run forwards
        y * MATRIX_WIDTH + x
    }
    return i
}

data class CRGB(var r: Int, var g: Int, var b: Int);