Problem in stretching an image

[Arrun]

Hi I am doing a image prcessing project in VC++, I am using bilinear interpolation for stretching the images but the image intensity varies before stretching and after stretching. for eg: If the image intensity for a square of 1 unit = 1xI1. If I stretch the image to 2 units then the intensity should be 2xI2 both the intensities should be equal ie 1xI1 = 2xI2 = k(constant) Pls help

[John M Drescher]

I think this is a result of roundoff. Are you doing your calculation with floating point numbers and translating them back to integers? John

[Arrun]

Thanks for ur reply Yes I am calculating it with floating point numbers and translating it back to integers. Is there a problem with that? or should I use density filter to get the same intensity