Fix loading of jpeg files not supported by standard java ImageIO (Kot…

…lin#384)

* Add TwelveMonkeys ImageIO plugin

* Add IO test with images from COCO 2017 test set, which failed to load using standard java ImageIO

dataset/build.gradle

@@ -2,6 +2,7 @@ project.setDescription("A KotlinDL library provides Dataset API and DSL to build
 
 dependencies {
     implementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21'
+    implementation 'com.twelvemonkeys.imageio:imageio-jpeg:3.8.2'
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.2'
     testImplementation 'org.junit.jupiter:junit-jupiter-engine:5.8.2'
     testImplementation 'org.junit.jupiter:junit-jupiter-params:5.8.2'

examples/src/test/kotlin/examples/io/IOTestSuite.kt

@@ -0,0 +1,31 @@
+package examples.io
+
+import examples.transferlearning.getFileFromResource
+import org.jetbrains.kotlinx.dl.dataset.image.ImageConverter
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertDoesNotThrow
+import javax.imageio.ImageIO
+import javax.imageio.ImageReader
+
+
+class IOTestSuite {
+    private val unsupportedJpegsFolder = getFileFromResource("jpeg_unsupported")
+
+    @Test
+    fun testJvmUnsupportedJpegLoading() {
+        val imageFiles = unsupportedJpegsFolder.walk().filter { it.isFile }
+
+        for (imageFile in imageFiles) {
+            assertDoesNotThrow("Failed to load image file $imageFile") {
+                imageFile.inputStream().use { inputStream -> ImageConverter.toBufferedImage(inputStream) }
+            }
+        }
+    }
+
+    @Test
+    fun testImageioJpegPluginIsUsed() {
+        val readers: Iterator<ImageReader> = ImageIO.getImageReadersByFormatName("JPEG")
+        val defaultReader = readers.next()
+        assert("com.twelvemonkeys.imageio.plugins.jpeg.JPEGImageReader" in defaultReader.toString()) { "Default jpeg reader should be com.twelvemonkeys.imageio.plugins.jpeg.JPEGImageReader" }
+    }
+}