Can you change the color scale to a define max in the visualizer page?
The built in visualizer allows you to modify several properties. You can select from three predefined color schemes that let you specify min and max values assigned to given color scheme.
For example, if you use greyscale scheme, you can define which value will correspond to white(max) and black(min). Any values in between will be automatically assigned corresponding shades of grey.
Here is an example showing the chart settings: