Rules clarification required (iii)

I've been watching a bit of tennis recently and I've noticed that accurately deciding whether a ball was 'in' or 'out' seems to have become a major issue, with Hawkeye playing its part, when someone can justify the cash spent to implement it.
But is the following 'in' or 'out' in a singles game?
Apologies for the colour and accuracy of the picture ... the red bit is the contact the ball makes with the ground while bouncing. At first look it would appear to be out; it has bounced just missing the junction between the baseline and the sideline. However, as far as the baseline line judge is concerned it was clearly in, and likewise the sideline judge looking straight up his line would call it in. Could the umpire overrule? Unlikely that he could see it clearly enough to be sure, and even if he could, how can you 'overrule' if neither of the line judge has made a mistake that needs to be over-ruled.
If it is on a Hawkeye court, would Hawkeye rule it out? If Hawkeye is not employed, what is the correct decision?