Background Image in RelativeLayout has artifacts

I created a background .png for my application in GIMP. It's resolution is 640x480, which from googling, seems to be the resolution for a default emulator. My problem is when I apply the background to the RelativeLayout with android:background=@drawable/bg and run it, there are lots of artifacts in the image. As if the emulator could not provide enough colors to display 开发者_JS百科the .png correctly. What is going on here?

P.S. This image is nothing to fancy, just simple lines and radial gradients.

It's resolution is 640x480, which from googling, seems to be the resolution for a default emulator

640x480 is not even an officially-supported resolution in Android, let alone a "default" one. Here is the list of supported resolutions.

Also, you want to watch your color depth. I forget the details, but not everything can necessarily handle 24-bit color, due to LCD limitations.

i've gathered 3 possible solutions:

1. for each problematic image that you have, create and use a bitmap drawable in the xml.

   the disadvantage is that you create multiple files. i've tested the other special flags (including the code changes), and haven't noticed any difference.

   res/drawable/image_file.xml

   <?xml version="1.0" encoding="utf-8"?>
   <bitmap xmlns:android="http://schemas.android.com/apk/res/android"
     android:src="@drawable/problematic_image" />
   

2. put the problematic image in the drawable-nodpi folder. the disadvantage is that it will use more RAM this way, as it doesn't downscale according to the density. a similar approach can be done in code:

   final BitmapFactory.Options options = new BitmapFactory.Options();
   options.inDensity = 1;
   options.inSampleSize = 1;
   options.inTargetDensity = 1;
   options.inJustDecodeBounds = false;
   final Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.problematic_image, options);
   imageView.setImageBitmap(bitmap);
   

3. if the file is a png file, take a pixel that is least noticable (for example the bottom-left), and change its opacity to 254 instead of 255.

   the disadvantage of this method is that it makes the image to take more space , and change the image itself.

all methods worked on galaxy s and galaxy s2 , with android 2.3.x .