Convert a Bitmap image to grayscale within BlackBerry J2Me - blackberry

Question

I have been trying to use the samples from here:
J2ME: Convert transparent PNG image to grayscale
and here:
http://www.java2s.com/Code/Java/Collections-Data-Structure/intarraytobytearray.htm
to convert an Bitmap image object to grayscale on the fly but I am running into issues when I am trying to re-encode my byte to an image and I get the following error/stack:
(Suspended (exception IllegalArgumentException))
EncodedImage.createEncodedImage(byte[], int, int, String) line: 367
EncodedImage.createEncodedImage(byte[], int, int) line: 279
ScreenTemp.getGrayScaleImage(Bitmap) line: 404
Here is my code I am trying:
Bitmap btemp = getGrayScaleImage(Bitmap.getBitmapResource("add.png"));
BitmapField bftemp = new BitmapField(btemp, BitmapField.FOCUSABLE | BitmapField.FIELD_HCENTER | BitmapField.FIELD_VCENTER);
add(bftemp);
public Bitmap getGrayScaleImage(Bitmap image) {
int width = image.getWidth();
int height = image.getHeight();
int[] rgbData = new int[width * height];
image.getARGB(rgbData, 0, width, 0, 0, width, height);
for (int x = 0; x < width*height ; x++) {
rgbData[x] = getGrayScale(rgbData[x]);
}
byte[] b = int2byte(rgbData);
final EncodedImage jpegPic = EncodedImage.createEncodedImage(b, 0, b.length);
return jpegPic.getBitmap();
}
private int getGrayScale(int c) {
int[] p = new int[4];
p[0] = (int) ((c & 0xFF000000) >>> 24); // Opacity level
p[1] = (int) ((c & 0x00FF0000) >>> 16); // Red level
p[2] = (int) ((c & 0x0000FF00) >>> 8); // Green level
p[3] = (int) (c & 0x000000FF); // Blue level
int nc = p[1] / 3 + p[2] / 3 + p[3] / 3;
// a little bit brighter
nc = nc / 2 + 127;
p[1] = nc;
p[2] = nc;
p[3] = nc;
int gc = (p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3]);
return gc;
}
private static byte[] int2byte(int[] src) {
int srcLength = src.length;
byte[]dst = new byte[srcLength << 2];
for (int i=0; i<srcLength; i++) {
int x = src[i];
int j = i << 2;
dst[j++] = (byte) ((x >>> 0) & 0xff);
dst[j++] = (byte) ((x >>> 8) & 0xff);
dst[j++] = (byte) ((x >>> 16) & 0xff);
dst[j++] = (byte) ((x >>> 24) & 0xff);
}
return dst;
}
Any help would be great!
Thanks,
Justin
EDIT:
Thanks to the below information I was able to fix this issue. Here is the code. You no longer need the int2byte and here is the updated the getGrayScaleImage method:
public Bitmap getGrayScaleImage(Bitmap image) {
int width = image.getWidth();
int height = image.getHeight();
int[] rgbData = new int[width * height];
image.getARGB(rgbData, 0, width, 0, 0, width, height);
for (int x = 0; x < width*height ; x++) {
rgbData[x] = getGrayScale(rgbData[x]);
}
byte[] b = int2byte(rgbData);
Bitmap bit = new Bitmap(width, height);
bit.setARGB(rgbData, 0, width, 0, 0, width, height);
return bit;
}

Answer 1

Quoting from the EncodedImage javadoc:
If the image format is not recognized, an IllegalArgumentException is thrown.
Why are you fiddling with EncodedImage? It seems like you ought to be able to just create a second Bitmap and use setARGB().

Answer 2

To extend Scott W answer.
EncodedImage.createEncodedImage(byte[] data, int offset, int length) expects a byte array of a supported image type (TIFF, BMP, JPEG, GIF, WBMP or PNG). For instance, if you opened a JPEG image file, read the file bytes, then it would be possible to use the got bytes to create an EncodedImage (it would be JPEGEncodedImage actually).
So as Scott W says you should use Bitmap.setARGB() for the resulting byte array to have a Bitmap with converted data.
And then if you need to save the image as a JPEG file, you can use smth like this:
JPEGEncodedImage eImage = JPEGEncodedImage.encode(bitmap, 75);
byte[] fileData = eImage.getData();
// open a FileConnection and write the fileData