BitmapData Memory Allocation

This test shows the bitmapdata memory allocation is not related to bitmapdata's area (it should be width*height*4).
The memory representation of a bitmapdata is 256bytes aligned for each row ( Math.max(height*(width/64),1)  ). This means that bitmaps occupation is significantly different depending on their orientation: vertical bitmaps are much larger than horizontal ones (up to 256x !!!)

In the chart: red line is a vertical bitmapdata occupation and blue line is the occupation of a horizontal one of the same area.

see this bug report in adobe jira https://bugbase.adobe.com/index.cfm?event=bug&id=3094186