I have an array of bytes that correspond to a "grayscaled bitmap" (one byte->one pixel), and I need to create a PNG file for this image.
The method below works, but the png created is HUGE, as the Bitmap I am using is an ARGB_8888 bitmap, which takes 4 bytes per pixel instead of 1 byte.
I haven't been able to make it work with other Bitmap.Config different than ARGB_8888. Maybe ALPHA_8 is what I need, but I have not been able to make it work.
I have also tried the toGrayScale method which is included in some other posts (Convert a Bitmap to GrayScale in Android), but I have the same issue with the size.
public static boolean createPNGFromGrayScaledBytes(ByteBuffer grayBytes, int width,
int height,File pngFile) throws IOException{
if (grayBytes.remaining()!=width*height){
Logger.error(Tag, "Unexpected error: size mismatch [remaining:"+grayBytes.remaining()+"][width:"+width+"][height:"+height+"]", null);
return false;
}
Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
// for each byte, I set it in three color channels.
int gray,color;
int x=0,y=0;
while(grayBytes.remaining()>0){
gray = grayBytes.get();
// integer may be negative as byte is signed. make them positive.
if (gray<0){gray+=256;}
// for each byte, I set it in three color channels.
color= Color.argb(-1, gray, gray, gray);
bitmap.setPixel(x, y, color);
x++;
if (x==width){
x=0;
y++;
}
}
FileOutputStream fos=null;
fos = new FileOutputStream(pngFile);
boolean result= bitmap.compress(Bitmap.CompressFormat.PNG,100,fos);
fos.close();
return result;
}
EDIT: Link to the generated file (it may look nonsense, but is just created with randon data). http://www.tempfiles.net/download/201208/256402/huge_png.html
Any help will be greatly appreciated.