I've learned the hard way that you can't tell the sex of pigeons by their appearance or even by their behaviour.
First I bought a "pair" of young Jacobins. They got along at first but then fought like cats and dogs, bow-cooing at each other day and night, and tore each others' hood feathers out, so I guessed they were male. I sold one because they couldn't be kept together. I put the remaining one with my Turkish tumbler hen (who looks almost exactly like the OP's bird). I knew the tumbler was female because she had previously laid eggs. They went into full courtship mode, preening and feeding each other. Guess who laid eggs - both of them! Both clutches were duds of course.
Then there's my "pair" of Indian fantails. The breeder (experienced and well known with his show birds) swore they were male and female. They got along fine with no displaying or fighting, and I was waiting for the eggs, which never came. I tried splitting them up, putting one with the tumbler hen and one with the Jacobin hen. They started courting immediately and both hens laid fertile eggs, which means both fantails are male.
There are only two ways to definitively sex a pigeon - DNA or whether they lay eggs. If you're not planning to breed them and just want a pet, the sex doesn't matter anyway. If you decide to get more birds - get some plastic eggs as well. Pigeons are very prolific.