Calculating the difference of two images (tif)



Hi everybody!
My friend and i calculated the difference-image of two tif-images (original one and the 8-bit-color-version of it with a smaller size than the original one) and we need to find out, why the resulting picture has a bigger size than the original one. we used the image-calculator-tool, then ‘difference’.
Does anyone know the answer?

Thanks for your help!!



Would you be able to post your two images so we can try to recreate this issue you are finding? It is still not completely clear to me… ie - when you say ‘smaller’, do you mean dimensionally, as in it is a cropped section of the original, etc?

Sorry - fuzzy brain today!