Just for convenience here is ready to copy and paste method:
public static void saveBitmapToJpg(Bitmap bitmap, File file, int dpi) throws IOException {
ByteArrayOutputStream imageByteArray = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, imageByteArray);
byte[] imageData = imageByteArray.toByteArray();
setDpi(imageData, dpi);
FileOutputStream fileOutputStream = new FileOutputStream(file);
fileOutputStream.write(imageData);
fileOutputStream.close();
}
private static void setDpi(byte[] imageData, int dpi) {
imageData[13] = 1;
imageData[14] = (byte) (dpi >> 8);
imageData[15] = (byte) (dpi & 0xff);
imageData[16] = (byte) (dpi >> 8);
imageData[17] = (byte) (dpi & 0xff);
}
saved file will have properly set Image DPI value: