How to use scaleToSize parameter to find image scaled non-proportionally

image “image100x100” size is 1006*753.

I can use following script to find image “image100x100” with 50% scale:
put imageFound(imageName: “image100x100”, scale: 0.5)

I can use following script to find image “image100x100” with 100% scale:
put imageFound(imageName: “image100x100”, scaleToSize: [1006, 753])

But I can’t use following script to find image “image100x100” with 50% scale:
put imageFound(imageName: “image100x100”, scaleToSize: [1006*.5, 753*.5])

What the problem?