ImageView rounded corners with Picasso

ImageView imageView = (ImageView) findViewById(R.id.image);
Picasso.with(getApplicationContext())
        .load(R.drawable.image)
        .transform(new RoundedTransformation(100, 0))
        .into(imageView);

public class RoundedTransformation implements com.squareup.picasso.Transformation {
    private final int radius;
    private final int margin;  

    public RoundedTransformation(final int radius, final int margin) {
        this.radius = radius;
        this.margin = margin;
    }

    @Override
    public Bitmap transform(final Bitmap source) {
        final Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setShader(new BitmapShader(source, Shader.TileMode.CLAMP, 
                Shader.TileMode.CLAMP));

        Bitmap output = Bitmap.createBitmap(source.getWidth(), source.getHeight(), 
                Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
        canvas.drawRoundRect(new RectF(margin, margin, source.getWidth() - margin, 
                source.getHeight() - margin), radius, radius, paint);

        if (source != output) {
            source.recycle();
        }
        return output;
    }

    @Override
    public String key() {
        return "rounded(r=" + radius + ", m=" + margin + ")";
    }
}

And if you need to create rounded corners on Bitmap:

public static Bitmap getRoundedCornerBitmap(Bitmap bitmap) {
    Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
            bitmap.getHeight(), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(output);

    final int color = 0xff424242;
    final Paint paint = new Paint();
    final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
    final RectF rectF = new RectF(rect);
    final float roundPx = 100;

    paint.setAntiAlias(true);
    canvas.drawARGB(0, 0, 0, 0);
    paint.setColor(color);
    canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

    paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
    canvas.drawBitmap(bitmap, rect, rect, paint);

    return output;
}