No, the triangle is what can be achieved by mixing the primaries. The blob is what the eye can distinguish between. I think the blob is the http://en.wikipedia.org/wiki/CIELUV_color_space but I'm not certain.
Can I suggest we look at http://en.wikipedia.org/wiki/CIE_1931_color_space#Definition... instead? There you can see that three primaries cover a large range of human colour perception. In particular yellow is well covered, but there is a big gap around cyan, hence my earlier comment that a cyan primary would seem more useful. This corresponds to the requirement for a negative red colour to reach between 440nm and 540nm. Note red is the only primary that goes significantly negative.
Also since we expect television to be displayed using three RGBish primaries, the triangle is also the only colours that are actually transmitted in any TV signal or recording.
Now, it is possible that the small gain in yellow is noticeable, and leads to a nice visual "pop" when viewing the screen, but it really isn't gaining you a lot. I'd be more interested in a cyan primary (think of the skies!) or an HDR screen with a real range of brightnesses.
Can I suggest we look at http://en.wikipedia.org/wiki/CIE_1931_color_space#Definition... instead? There you can see that three primaries cover a large range of human colour perception. In particular yellow is well covered, but there is a big gap around cyan, hence my earlier comment that a cyan primary would seem more useful. This corresponds to the requirement for a negative red colour to reach between 440nm and 540nm. Note red is the only primary that goes significantly negative.
Also since we expect television to be displayed using three RGBish primaries, the triangle is also the only colours that are actually transmitted in any TV signal or recording.
Now, it is possible that the small gain in yellow is noticeable, and leads to a nice visual "pop" when viewing the screen, but it really isn't gaining you a lot. I'd be more interested in a cyan primary (think of the skies!) or an HDR screen with a real range of brightnesses.