CODEWITHSUNDEEP
java
user1621008
user1621008

Reputation: 13

Converting pixel color (bytes to bits & bits to bytes)

I wanted to manipulate the image by playing with the pixel bits. So, I wanted to covert the pixels I grabbed from PixelGrabber. The argb value were in bytes. Now I want to convert array of bytes into bits and manipulate it. And then convert back to bytes array.

For Example: -1057365 into 11101111 11011101 10101011 11111111 and 11101111 11011101 10101011 11111111 into -1057365

Anyone know there's any efficient way to converting between them? Or java has method implemented for it and I don't know.

Thx for helping.

Upvotes: 1

Views: 2525

Answers (2)

Jeffrey
Jeffrey

Reputation: 44808

You might want to take a look at BitSet.

byte[] argb = ...
BitSet bits = BitSet.valueOf(argb);
bits.set(0); // sets the 0th bit to true
bits.clear(0); // sets the 0th bit to false

byte[] newArgb = bits.toByteArray();

/edit
To convert a byte[] to an int:

int i = 0;
for(byte b : newArgb) { // you could also omit this loop
    i <<= 8;            // and do this all on one line
    i |= (b & 0xFF);    // but it can get kind of messy.
}

or

ByteBuffer bb = ByteBuffer.allocate(4);
bb.put(newArgb);
int i = bb.getInt();

Upvotes: 0

HLL
HLL

Reputation: 199

I Assume that the value that you have is a raw 4-byte int representation of the ARGB code. Each of the channels is 1 byte wide ranging from 0 to 254, together they make up the whole range of 0-255^4 (minus 1).

The best way you can acquire the different channel values is by combination of masking and shifting the argb value into different fields. 

int alpha = (pixel >> 24) & 0xff;
int red   = (pixel >> 16) & 0xff;
int green = (pixel >>  8) & 0xff;
int blue  = (pixel      ) & 0xff;

Source

Upvotes: 4

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