Grey Heron

Not sure where you get Great Blue Heron from, that is not even an Asian species and it would have brown thighs which this clearly does not have. I have added my lightened version of your picture as a second picture for your perusal. I gave you a suggestion with the correct species.

Scroll down to the Grey Heron section and look at the picture, the wings can be very dark below, and taking the photograph with the sun above makes it look much darker. I ran your picture through a photographic program to correct the lighting and it is clearly a Grey Heron.

That bird is beautiful. btw- Hi Coach Fox! You were the coach for the girls soccer B team, but I was on A. I'm Kira. Awesome spotting! See you later!

Oh never mind I don't know in Singapore.

I was thinking the same thing, tough light, but I'd say great blue heron

Since I can't see the colors some possibilities could be Great-billed Heron, Ardea sumatrana Purple Heron (Ardea purpurea