java.lang.IllegalArgumentException: im == null!

I am getting the following output after executing the attached code:

Code:

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Available: 109980
Reader is not found
Image is NULL
java.lang.IllegalArgumentException: im == null!
        at javax.imageio.ImageIO.write(Unknown Source)
        at javax.imageio.ImageIO.write(Unknown Source)
        at Main_TEST.main(Main_TEST.java:48)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:271)

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Can anyone please give me a solution to this problem, or can anyone suggest me any alternative ways to write image after bit-manipulation.

Thanks in advance in anticipation of an early reply.

The problem is that at line 34: "new_img = ImageIO.read(in);", ImageIO can't read the InputStream.

And that was because I modified some header information of the image..can you please tell me how can get header information of an image format..

I don't know, I've never had to manually edit header information. Google might help in this situation.

i have run your application, the same exception thrown out. after i debug your application, i found some errors.
new_img = ImageIO.read(in);.
functions "read()" ->public static BufferedImage read(InputStream input) throws IOException return a BufferedImage. if it does't exits a registered ImageReader that claims can get the inputstream ,it would return null. that is said your inputstream is null in fact. So the problem is here, the inputstream is null, it would throw the exception(IllegalArgumentException).Maybe i doesn't express myself clear, i suggest you to see the API-ImageIO.read. I think you will have a better understanding...;)