We have only red, blue and green receptors (everything you see is a mixture of those colors) and they have like four or five colors they can see.
I can totally agree on what Chris. wrote, and I just want to give an idea on how this might look like for them:
Have you even been under an orange street lamp, trying to read a printed map or look at something? Looked around, how everything looks like being in shades of orangey-greyish?
That's because now we can only see a small part of the spectrum we are usually able to see under natural daylight.
For a dragon it mus be similar when he sees you usually indoors: Only a part of the natural daylight (because: indoors, no UV he could see), also less than in the enclosure (we're never mimicking a natural solar spectrum perfectly, even not with the UV lamps), so you must appear kind of "greyish". Outdoors, he suddenly sees you in all colors, looking overwhelming different!
And don't worry, my big boy saw the outside world for the first time when he was eight months old and he would puff up and open his mouth at me like I've never seen him. He was quite intimidating as he was already quite big at this age.
Mine was outside (on the balcony, very bright, high UV index) at an age of about 7 months for the first time. Not puffing up or so (he's done that once, indoors, when my partner who is not my dragon's primary human but rather rarely interacts with him re-arranged things in the enclosure). But, also looked to be overwhelmed and tried hiding at me (he already trusted me a lot, my dragon is a super calm boy who lets me touch each part of his body, lets me put on a harness on him).
Generally, it's normal for them to be very cautious when they are babies. When they are juveniles, it gradually changes. I remember very well my dragon (inside his enclosure) hid from me when I entered the room. Now, him being 10 months old, since a few months I can gently lift his legs to put them through the loops of his harness (big step from "hides when I enter the room"! steps in between likes "does not hide when I enter the room", "does not hide when I open the enclosure", "lets me pet the stone (!) next to him", "lets me pet him a second on the back", "lets me touch even parts like the feet, head, base of tail", "lets me pick him up"). When before he was scared by normal household activities (so sorry little guy, but cooking or cleaning is impossible to be done noiseless), and the worst was me doing laundry (clothes must have looked like flapping birds! but so sorry little guy, we had to bring them somehow from the washing machine to the balcony and back in), now he eagerly comes and looks when I come home with groceries and put them away, or when I iron a load of clothes.
