June 2018 Update

Task/Grayscale-image/Kotlin/grayscale-image.kotlin

@@ -0,0 +1,27 @@
+// version 1.2.10
+
+import java.io.File
+import java.awt.image.BufferedImage
+import javax.imageio.ImageIO
+
+fun BufferedImage.toGrayScale() {
+    for (x in 0 until width) {
+        for (y in 0 until height) {
+            var argb  = getRGB(x, y)
+            val alpha = (argb shr 24) and 0xFF
+            val red   = (argb shr 16) and 0xFF
+            val green = (argb shr  8) and 0xFF
+            val blue  =  argb and 0xFF
+            val lumin = (0.2126 * red + 0.7152 * green + 0.0722 * blue).toInt()
+            argb = (alpha shl 24) or (lumin shl 16) or (lumin shl 8) or lumin
+            setRGB(x, y, argb)
+        }
+    }
+}
+
+fun main(args: Array<String>) {
+    val image = ImageIO.read(File("bbc.jpg")) // using BBC BASIC image
+    image.toGrayScale()
+    val grayFile = File("bbc_gray.jpg")
+    ImageIO.write(image, "jpg", grayFile)
+}