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POByteArrayOutput/InputStream on transparent image
 

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    <p>I'm trying to send a <code>BufferedImage</code> over socket, I do this by converting the image to <code>byte[]</code> and then send it over after encoding it in Base64. I'm sending over 2 BufferedImages, one of them is "full", the other one is about 50% transparent. The problem I'm having, is that when they arrive, the second image is still visually transparent, but when I get the data array via Raster, it has been changed.</p> <p>I made a small test code to demonstrate the problem;</p> <pre><code> BufferedImage levelBufferedOriginal = ... BufferedImage backgroundBufferedOriginal = ... byte[] levelDataOriginal = ((DataBufferByte) levelBufferedOriginal.getRaster().getDataBuffer()).getData(); byte[] backgroundDataOriginal = ((DataBufferByte) backgroundBufferedOriginal.getRaster().getDataBuffer()).getData(); ByteArrayOutputStream baos = new ByteArrayOutputStream(); byte[] temp = null, temp2=null; try { ImageIO.write(levelBufferedOriginal, "png", baos); baos.flush(); temp = baos.toByteArray(); baos.close(); baos=new ByteArrayOutputStream(); ImageIO.write(backgroundBufferedOriginal, "png", baos); baos.flush(); temp2 = baos.toByteArray(); baos.close(); } catch (IOException e1) { e1.printStackTrace(); } BufferedImage levelBufferedNew = null; BufferedImage backgroundBufferedNew = null; try { levelBufferedNew = ImageIO.read(new ByteArrayInputStream(temp)); backgroundBufferedNew = ImageIO.read(new ByteArrayInputStream(temp2)); } catch (IOException e) { e.printStackTrace(); } byte[] levelDataNew = ((DataBufferByte) levelBufferedNew.getRaster().getDataBuffer()).getData(); byte[] backgroundDataNew = ((DataBufferByte) backgroundBufferedNew.getRaster().getDataBuffer()).getData(); System.out.println("LEVEL: " + Arrays.equals(levelDataOriginal, levelDataNew)); System.out.println("BACKGROUND: " + Arrays.equals(backgroundDataOriginal, backgroundDataNew)); </code></pre> <p>All I do here, is simply transform the <code>BufferedImage</code> to <code>byte[]</code>, then back, and compare the data I get from <code>DataBufferByte</code>. The output is</p> <blockquote> <p>LEVEL: false </p> <p>BACKGROUND: true</p> </blockquote> <p>Background is the "full" image, and Level is the one with some transparent pixels.</p> <p>If the general idea is wrong, I would like to hear another, all I want is to be able to exactly recreate 2 bufferedImages.</p>
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    1. COAre the images visually different? As you mention, the images are translucent. It could be that the PNG encoding/decoding roundtrip changes the values for some transparent pixels, without affecting the visuals of the image. See premultiplied alpha vs non-premultiplied.
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    2. COThe images visually are the same. Problem I get, is when I start editing the level image data (levelDataNew) to "-1" (to set a pixel transparent), it becomes black instead, so I don't see the background behind it. Whereas an edit to levelDataOriginal will set the pixel transparent.
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    3. COWhat do you mean by "-1"? 0xFF? A completely transparent pixel is 0x0, while a completely opaque one should be 0xff. Also, the premultiplied state is important, if you are trying to "fade in" what you already have "faded out" (made transparent).
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