Working with data that was created as "unsigned short"

[Nate Lockwood]

I have special cameras that output a stream of "unsigned shorts" (as in C) to a file. There are only 12 valid bits and I had assumed that they were stuffed in the LSB so that Java would see them all as positive. I'm at the point where I can display an image with my own code but it's not quite right compared to ImageJ. My calculation of maximum and minimum values are too large, don't match that of ImageJ, and the minimum value is negative. I suspect that the valid bits are the MSB
I'd like to shift the bits to the right but suspect that there will be a conversion to an int which will conserve the sign.

How can I convert these shorts?

TIA

[Henry Wong]

Nate Lockwood wrote:I have special cameras that output a stream of "unsigned shorts" (as in C) to a file. There are only 12 valid bits and I had assumed that they were stuffed in the LSB so that Java would see them all as positive. I'm at the point where I can display an image with my own code but it's not quite right compared to ImageJ. My calculation of maximum and minimum values are too large, don't match that of ImageJ, and the minimum value is negative. I suspect that the valid bits are the MSB
I'd like to shift the bits to the right but suspect that there will be a conversion to an int which will conserve the sign.

How can I convert these shorts?

A conversion from short to int will "sign extend" the value. So, to avoid that you need to mask out the higher order bits.... Something like...

short s = getSomeSixteenBitValueAsSignedShort();
int i = s & 0xffff; 

Henry

[Nate Lockwood]

Thanks, that preserves the data. Now to see what happens in my code!