Change contrast on an image

Question

hi i am tryin to change the contrast of an image using lookup operation i am using a sinosuidal function for the look up table but the problem is that the original image doesnt retorn to its origin any help will be welcome
//return cambiaBrillo1(contraste, img);
byte[] lut = new byte[256];
for (int i = 0; i < 256; i++)
double scale = i + (contraste * Math.sin( (0.0245 * i) - 3.14));
if (scale > 255.0)
scale = 255.0;
else if (scale < 0.0)
scale = 0.0;
lut[i] = (byte) scale;
LookupTableJAI lookup = new LookupTableJAI(lut);
ParameterBlock pb = new ParameterBlock();
pb.addSource(img);
pb.add(lookup);
return JAI.create("lookup", pb);

Answer 1

OK. I see the solution now. I had a theme selected to add opening titles. The border set on the pic-in-pic image looked the same colour as that theme. So I set the theme to No Theme and the image's border went away.