Wow! Thanks Kevin.
For some reason I was not getting a result by using a null.
So I used the lens flare effect as described by dan ebberts on his website. (Taken there by link from adobe AE expression help on SampleImage.
With this expression and intensity of flare down to 0%, I am getting the result.
target=thisComp.layer(“cellDeath.mov”);
target.sampleImage(target.effect(“Lens Flare”)(“Flare Center”),[1,1]);