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POConverting transparent gif / png to jpeg using java
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copied!<p>I'd like to convert gif images to jpeg using Java. It works great for most images, but I have a simple transparent gif image:</p> <p><a href="http://img292.imageshack.us/img292/2103/indexedtestal7.gif">Input gif image http://img292.imageshack.us/img292/2103/indexedtestal7.gif</a></p> <p>[In case the image is missing: it's a blue circle with transparent pixels around it]</p> <p>When I convert this image using the following code:</p> <pre><code>File file = new File("indexed_test.gif"); BufferedImage image = ImageIO.read(file); File f = new File("indexed_test.jpg"); ImageIO.write(image, "jpg", f); </code></pre> <p>This code works without throwing an Exception, but results an invalid jpeg image:</p> <p><a href="http://img297.imageshack.us/img297/3493/indexedtest1qe5.jpg">Output jpeg image http://img297.imageshack.us/img297/3493/indexedtest1qe5.jpg</a></p> <p>[In case the image is missing: IE cannot show the jpeg, Firefox shows the image with invalid colors.]</p> <p>I'm using Java 1.5. </p> <p>I also tried converting the sample gif to png with gimp and using the png as an input for the Java code. The result is the same.</p> <p>Is it a bug in the JDK? How can I convert images correctly preferably without 3rd party libraries?</p> <p><strong>UPDATE:</strong></p> <p>Answers indicate that jpeg conversion cannot handle transparency correctly (I still think that this is a bug) and suggest a workaround for replacing transparent pixels with predefined color. Both of the suggested methods are quite complex, so I've implemented a simpler one (will post as an answer). I accept the first published answer with this workaround (by Markus). I don't know which implementation is the better. I go for the simplest one still I found a gif where it's not working.</p>

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