HeatMap : How to normalize color in the Y axis

[dp297]

I have a standard Heatmap with 50 elements in the X axis and 50 in the Y axis. However, the Color Grading of the Heatmap takes the highest weight and normalizes based on that.
I would like to normalize the color grading for each Y axis element.
The way I create the Heatmap is by adding to a Series Collection individual HeatSeries, each one with a new HeatMap. However, it still works as described above!