// Simple

function inRange(x, min, max)
{
    return x >= min && x <= max;
}

image.width = 10;
image.height = 10;
limits.minWidth = 5;
limits.maxWidth = 5;
limits.minHeight = 5;
limits.maxHeight = 5;

if (!inRange(image.width, limits.minWidth, limits.maxWidth) ||
    !inRange(image.height, limits.minHeight, limits.maxHeight)) {
    throw new Error("Image incorrect size");
}