DislikedI do not think that spread distorts chart since since only bid level is recorded.
I see each broker has different feed.
Just very curious is there any currency centralized price level.
What do these heard sessions like London, NY, Tokyo do?
Do not they centralized price level?
Then from where liquidity providers take the price?
Liquidity providers don't "take the price" from anywhere. The price you see is the best (highest bid and lowest ask) that all the aggregated liquidity gives. If you are looking for historical data
http://truefx.com/ is a pretty good resource.