Grayscale image: Difference between revisions
Added Kotlin
m (→{{header|REXX}}: changed a literal (version).) |
(Added Kotlin) |
||
Line 926:
The task description is silent on the issue of companded sRGB versus linear RGB. Most images are actually sRGB, and strictly speaking, the transformation to get Y from RGB is applicable to linear RGB. I imagine that, unlike the ''rc'' version, the ''julia'' version reverses compansion prior to applying the CIE transformation to extract luminance from RGB.
=={{header|Kotlin}}==
This just converts a colored image to grayscale.
As it's not possible to recover the original colored image (because different combinations of RGB values could have produced the same luminance), I have not bothered with the reverse operation.
<lang scala>// 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)
}</lang>
{{out}}
<pre>
Images same as BBC BASIC entry
</pre>
=={{header|Lingo}}==
| |||