Sure, here is one sample of my RGB mask:
[[[107 142  35]
[107 142  35]
[107 142  35]
…
[ 70 130 180]
[ 70 130 180]
[ 70 130 180]]
[[107 142  35]
[107 142  35]
[107 142  35]
…
[ 70 130 180]
[ 70 130 180]
[ 70 130 180]]
[[107 142  35]
[107 142  35]
[107 142  35]
…
[ 70 130 180]
[ 70 130 180]
[ 70 130 180]]
…
[[128  64 128]
[128  64 128]
[128  64 128]
…
[128  64 128]
[128  64 128]
[128  64 128]]
[[128  64 128]
[128  64 128]
[128  64 128]
…
[128  64 128]
[128  64 128]
[128  64 128]]
[[128  64 128]
[128  64 128]
[128  64 128]
…
[128  64 128]
[128  64 128]
[128  64 128]]]
The shape is (375, 1242, 3)