Java: BufferedImage to byte array and back
Solution 1
This is recommended to convert to a byte array
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(img, "jpg", baos);
byte[] bytes = baos.toByteArray();
Solution 2
Note that calling close
or flush
will do nothing, you can see this for yourself by looking at their source/doc:
Closing a ByteArrayOutputStream has no effect.
The flush method of OutputStream does nothing.
Thus use something like this:
ByteArrayOutputStream baos = new ByteArrayOutputStream(THINK_ABOUT_SIZE_HINT);
boolean foundWriter = ImageIO.write(bufferedImage, "jpg", baos);
assert foundWriter; // Not sure about this... with jpg it may work but other formats ?
byte[] bytes = baos.toByteArray();
Here are a few links concerning the size hint:
Of course always read the source code and docs of the version you are using, do not rely blindly on SO answers.
user1875290
Updated on July 05, 2022Comments
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user1875290 about 2 years
I see that a number of people have had a similar problem, however I'm yet to try find exactly what I'm looking for.
So, I have a method which reads an input image and converts it to a byte array:
File imgPath = new File(ImageName); BufferedImage bufferedImage = ImageIO.read(imgPath); WritableRaster raster = bufferedImage .getRaster(); DataBufferByte data = (DataBufferByte) raster.getDataBuffer();
What I now want to do is convert it back into a BufferedImage (I have an application for which I need this functionality). Note that "test" is the byte array.
BufferedImage img = ImageIO.read(new ByteArrayInputStream(test)); File outputfile = new File("src/image.jpg"); ImageIO.write(img,"jpg",outputfile);
However, this returns the following exception:
Exception in thread "main" java.lang.IllegalArgumentException: im == null!
This is because the BufferedImage img is null. I think this has something to do with the fact that in my original conversion from BufferedImage to byte array, information is changed/lost so that the data can no longer be recognised as a jpg.
Does anyone have any suggestions on how to solve this? Would be greatly appreciated.
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Christophe Roussy over 10 yearsFlush and close will do nothing
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hguser about 10 yearsIs there a special reason to use jpg here?
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user207421 almost 10 yearsAnd if close() didn't do anything it would call flush() itself, and it would be necessary to call itbefore toByteArray(), not after it.