How image to seed is calculated

[Creative-comfyUI]

Image to seed can be a very interesting function. To use it, we need to understand how it is calculated

If I understand well, the seed number of a batch image defines all the images of the batch. Each image of a batch is a variation of this number, this variation is determined by a formula with a strength value. The number for each of the images obtained by "image to seed" is the result of this formula. Am I right? What is the formula to retrieve the noise seed ?