diff --git a/README.md b/README.md
index 0a09adb..85fc816 100644
--- a/README.md
+++ b/README.md
@@ -13,12 +13,12 @@ mvn package
 
 ### run by jar
 ```shell
-java -jar ./target/dist/lib/bioformats-imageinfo-1.1.0.jar "[path to image file]"
+java -jar ./target/dist/lib/bioformats-imageinfo-1.1.1.jar "[path to image file]"
 ```
 
 ### run by fat jar
 ```shell
-java -jar ./target/bioformats-imageinfo-1.1.0-jar-with-dependencies.jar "[path to image file]"
+java -jar ./target/bioformats-imageinfo-1.1.1-jar-with-dependencies.jar "[path to image file]"
 ```
 
 ### library usage
diff --git a/pom.xml b/pom.xml
index b8c191d..43c77b4 100644
--- a/pom.xml
+++ b/pom.xml
@@ -5,7 +5,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>jp.riken.neurodata.tools.BioFormatsImageInfo</groupId>
   <artifactId>bioformats-imageinfo</artifactId>
-  <version>1.1.0</version>
+  <version>1.1.1</version>
 
   <name>bioformats-imageinfo</name>
   <url>https://neurodata.riken.jp</url>
diff --git a/src/main/java/jp/riken/neurodata/tools/BioFormatsImageThumbnail.java b/src/main/java/jp/riken/neurodata/tools/BioFormatsImageThumbnail.java
index 3d78357..19a6504 100644
--- a/src/main/java/jp/riken/neurodata/tools/BioFormatsImageThumbnail.java
+++ b/src/main/java/jp/riken/neurodata/tools/BioFormatsImageThumbnail.java
@@ -4,7 +4,6 @@ import java.awt.Color;
 import java.awt.Graphics2D;
 import java.awt.Image;
 import java.awt.image.BufferedImage;
-import java.io.BufferedOutputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileOutputStream;
@@ -105,12 +104,14 @@ public class BioFormatsImageThumbnail {
 
     protected static byte[] getPngByteArray(final BufferedImage image) throws BioFormatsImageException {
         byte[] ret = null;
-        try (ByteArrayOutputStream baos = new ByteArrayOutputStream();
-                BufferedOutputStream bos = new BufferedOutputStream(baos);) {
-            image.flush();
-            ImageIO.write(image, "png", bos);
-            bos.flush();
-            bos.close();
+        try (final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+                final ImageOutputStream ios = ImageIO.createImageOutputStream(baos);) {
+            final ImageWriter writer = ImageIO.getImageWritersByFormatName("png").next();
+            final ImageWriteParam param = writer.getDefaultWriteParam();
+            param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
+            writer.setOutput(ios);
+            writer.write(null, new IIOImage(image, null, null), param);
+            writer.dispose();
             ret = baos.toByteArray();
         } catch (final IOException e) {
             throw new BioFormatsImageException(e);
@@ -131,6 +132,9 @@ public class BioFormatsImageThumbnail {
             default:
                 throw new BioFormatsImageException("Unsupported image format: " + mimeType);
         }
+        if (bytes.length == 0) {
+            throw new BioFormatsImageException("Failed to convert to " + mimeType + " format");
+        }
         final String dataUri = "data:" + mimeType + ";base64," + Base64.getEncoder().encodeToString(bytes);
 
         return dataUri;