Why the color of the image changed when it compressed by Bitmap.CompressFormat.JPEG

Question

I am trying to compress the photo took by the camera in Android. But the color of the image changed when it compressed by Bitmap.CompressFormat.JPEG. How can I solve this problem? Thanks

I have put some sample images which generated from my code. You can see the color of the paper on the top of the images is different.

Here is the code snippet:

Bitmap bitmap = BitmapFactory.decodeFile(Common.FOLDER_PATH + "pic.jpg");

FileOutputStream stream2 = new FileOutputStream(Common.FOLDER_PATH + "pic100.jpg");         
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream2); 

FileOutputStream stream3 = new FileOutputStream(Common.FOLDER_PATH + "pic100.png");         
bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream3);

This is original image:
This is JPEG:
This is PNG:

Answer 1

JPEG is a lossy compression format and there may be loss of image information during the compression. The sacrifice of original image information is made for a better compression ratio (resulting in smaller file).

However, if this is not acceptable for you, you should use one of the lossless compression methods which includes the PNG.