The dress is a bistable picture, similar to the Spinning Dancer, which you can consciously reverse the direction of spin with some practice.
To see the dress as blue-black, I first look at the black dress in the bottom-left corner, then shift gaze to the main dress when colour is established.
To see the dress as white-gold, I first look at the sunny regions on the right, then move gaze across, when the main dress goes to white-gold.
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It may help to cover or mask the opposite region, when focusing on one side.
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For detail, 10 years ago I saw this as white-gold and did not change from that perception. Did not know what all the fuss was about this dress. Today, I saw it as white-gold initially, but 10 minutes later, after two friends saw it as blue-black, I also saw it as blue-black and could not shake it.
It’s like the best bits of Q3A and UT combined.
Just be aware, some other online players will modify opponent skins to be extra hi-vis(cheating).
Good to give you an extra challenge.