Hi, I am trying to put a black background on this pic, but when i'm using the select tool, it wont stay on the actual subject. Is this because the lighting isnt right and it can't work out what the focus point should be?
Is this using Photoshop? Also an unedited version of the image would be useful to give a better idea of what you are asking the software to achieve. If it's Photoshop and probably applies with other similar software, the select tool is not an exact science and will work within a set of parameters to try and select an area or areas of the image which are distinguishable from other areas. It doesn't work on focus points it just outlines something which is different to what's next to it. Yes it has improved over time but still doesn't do ambiguity very well if parts of an image are not easy to distinguish from what surrounds it.
What Tim said.
The best option is to start with the colour image too.
His hair is a similar grey to the furniture but I bet it’s a completely different colour.
A select tool is looking for object edges, there’s lots more options in colour.