Adjusting brightness in images using JAI lookup tables

[Amy]

Hi,

I have written a program using JAI for a project I am doing which can
be used to adjust the brightness of an image. It all works fine but I
now need to write it all up and am not entirely sure what it is doing.

The code is below:

public void adjustLight(int ipParam){ // ipParam = 18
pb = new ParameterBlock();
pb.addSource(image);
byte lookUpTableData[];
lookUpTableData = new byte[256];
for(int j = 0; j < 256; j++){
lookUpTableData[j] = clampByte(j + ipParam);
}

LookupTableJAI lookUp = new LookupTableJAI(lookUpTableData);
pb.add(lookUp);

image = JAI.create("lookup", pb, null);
tellObservers();
}

private final byte clampByte(int i){
if(i > 255)
return -1;
if(i < 0)
return 0;
else
return (byte)i;
}

I am unsure about what the clampByte method is doing and was a bit
confused by the lookup operation.

If anyone could help I would be very grateful. Thank you.

Amy