How to convert 10bit unsigned bytearray to uint16 bytearray in C? - c

Question

I have an img in binary format format.
Each pixel is 10bit.
They are putted consecutively, like [9-2] in first byte and [1:0] in second byte.
Where 9 IS MSB bit, 0 - LSB.
How to convert them to 16bit array?
E.g:
Store like 8 bit:
0b10000011,
0b10101100,
0b10011001,
0b11000000,
0b10101000,
Actual data which contains real pixels and which I want convert to 16bit:
0b1000001110,
0b1011001001,
0b1001110000,
0b0010101000,

Answer 1

It seems you want to convert data like this
img[0] = AAAAAAAA
img[1] = AABBBBBB
img[2] = BBBBCCCC
img[3] = CCCCCCDD
img[4] = DDDDDDDD
to data like this:
array[0] = 000000AAAAAAAAAA
array[1] = 000000BBBBBBBBBB
array[2] = 000000CCCCCCCCCC
array[3] = 000000DDDDDDDDDD
It can be done like this:
array[0] = ((img[0] << 2) | (img[1] >> 6)) & 0x3ff;
array[1] = ((img[1] << 4) | (img[2] >> 4)) & 0x3ff;
array[2] = ((img[2] << 6) | (img[3] >> 2)) & 0x3ff;
array[3] = ((img[3] << 8) | img[4] ) & 0x3ff;
To convert multiple blocks, for loop is useful like this:
for (int i = 0; (i + 1) * 5 <= num_of_bytes_in_img; i++) {
array[i * 4 + 0] = ((img[i * 5 + 0] << 2) | (img[i * 5 + 1] >> 6)) & 0x3ff;
array[i * 4 + 1] = ((img[i * 5 + 1] << 4) | (img[i * 5 + 2] >> 4)) & 0x3ff;
array[i * 4 + 2] = ((img[i * 5 + 2] << 6) | (img[i * 5 + 3] >> 2)) & 0x3ff;
array[i * 4 + 3] = ((img[i * 5 + 3] << 8) | img[i * 5 + 4] ) & 0x3ff;
}
(this loop won't convert last a few bytes, so you should treat them separately or add padding to img not to read out-of-range while using this loop to end of the image)