Over the years I have been working wiht many different stains and i can say with complete certainty that blood is never easy to remove and one has to deal with it while it is still wet otherwise it will be very challenging to get rid of.
This particular photo on your right is one i dealt with some time ago and it was not as bad as it looked as it was not completely dry, method i use is a wet extraction. however one has to be very mindful not to heat up water to boiling as it will make blood bind with carpet and in result it will be a nightmare to remove.
if you are not using any extraction method get yourself ready for a very long process and one that may result in more mess then actual clean carpet.
To start with get some water and cloth to get excess of blood from carpet, you can use a simple hoover with cloth at its extraction hose to such up nice amount of blood once its wet and allows to break off from carpet. its bert solution i found to work if you don’t have professional equipment.
As a last result if you are in cardiff area just ring us and we will do it for you with always great results.