fix convert string

src/main/scala/ch/memobase/MediaTransformations.scala

@@ -91,22 +91,22 @@ object MediaTransformations extends Logging {
    */
   def createImageThumbnail(sourceFilePath: String, destFile: String, width: Option[Int], height: Option[Int]): Try[String] = {
     val externalCommand =
-      s"""convert \\
-         |-filter Triangle \\
-         |-define filter:support=2 \\
-         |-thumbnail ${width.getOrElse("")}x${height.getOrElse("")} \\
-         |-unsharp 0.25x0.08+8.3+0.045 \\
-         |-dither None \\
-         |-posterize 136 \\
-         |-quality 82 \\
-         |-define jpeg:fancy-upsampling=off \\
-         |-define png:compression-filter=5 \\
-         |-define png:compression-level=9 \\
-         |-define png:compression-strategy=1 \\
-         |-define png:exclude-chunk=all \\
-         |-interlace none \\
-         |$sourceFilePath \\
-         |$destFile""".stripMargin
+      s"""convert
+         |-filter Triangle
+         |-define filter:support=2
+         |-thumbnail ${width.getOrElse("")}x${height.getOrElse("")}
+         |-unsharp 0.25x0.08+8.3+0.045
+         |-dither None
+         |-posterize 136
+         |-quality 82
+         |-define jpeg:fancy-upsampling=off
+         |-define png:compression-filter=5
+         |-define png:compression-level=9
+         |-define png:compression-strategy=1
+         |-define png:exclude-chunk=all
+         |-interlace none
+         |$sourceFilePath
+         |$destFile""".stripMargin.replaceAll("\n", " ")
     Try {
       executeCommand(externalCommand)
       destFile