At a minimum you would want to adjust the color gamut of the image by hand to line up with the lego color gamut so the end result is more pleasing, more concretely that means spending some time on the hue/saturation/lightness/color curve filters until those conversion artifacts are minimized. A more theoretically interesting way to do it would be to use a gamut matching algorithm with a discrete color space defined by the available lego bricks.
And taking the step to actually getting out of the digital world is something everybody should probably do more often!
In this case, the aggregation algorithm not only creates rectangular areas, but also avoids the need for the quilter to have to sew Y-seams.
Here's my talk from RacketCon:
Noooooo. RGB is not useful for anything but computer displays. Always use a suitable color space if you want to calculate with color values. Eg a CieLAB one or similar.
Sometimes "good enough" works.
Even beyond that though, there is something to be said for seeking to approach perfection. Nobody is requiring or expecting perfection, but when someone offers an easy way to get closer to it, it will rub many the wrong way when someone rebukes the helpful suggestion with the excuse of “good enough is fine, so stop providing helpful product improvement advise!” This is how you achieve mediocrity.
EDIT: after looking into this: CieLAB is still beyond scope, but a good solution for nearest color when you want to be accurate to that degree.
This seems to be to be one of those cases where the simple and obvious approach appears to give a better result than the 'correct' approach
There are a few other pictures and how well the medium of Lego works for pixelated art.
There are a few people on this thread posting 'things made with Lego' which is a different thing to using Lego for pixelated art.
I think that you could build a small business out of making pixelated Lego for people wanting to buy their new-borns some Lego. Imagine if in the bedroom the Lego starts as a bright picture on the wall, out of reach. Then when they can reach it then see what happens. If they have no Lego then do they work out that you can make things with it? Or do we need marketing and instructions with box artwork?
Also interesting would be a Lego sorting machine that you tipped random bricks into for it to then print out as pixelated art. It would scan the bricks and then show you exactly what images you could make from the bricks and also dither a given image to the palette and availability provided by the bricks dropped into the sorter.
I'll say cross-stitchers beat everyone to it.
Made any updates to your neural net implementation? I’m working through some deep learning intro courses right now, and I can better appreciate your approach.
With pixel art that uses models, part of the challenge tends to be not to be as accurate as possible, but to deviate in the ways that best brings out the overall qualities of the image.
E.g. in this case I'd argue that the big flaw in the end result was to not bring out the blue in her head-dress and the white and black in her eyes, and ensuring the back of her head and back is actually visible, at least with a dark grey outline, as well as the red line of her mouth.
Likewise, sacrificing some of the lines in her headdress for less texturing but hinting at it with maybe one line would probably look better.
I don't want to diminish it in terms of demonstration of the methods in the article - it's great as a means of showing what you can do with them. But it also demonstrates shortcomings of those methods (but that's good too).
Here's a portrait of R2D2: https://www.flickr.com/photos/152507766@N07/32877646570/
and here's the Millenium Falcon: https://www.flickr.com/photos/legocityson/37717492631/in/dat...
and Groucho Marx: https://www.flickr.com/photos/125619484@N02/29571498821
and a self-portrait (not me): https://www.flickr.com/photos/142720019@N08/33587002231/in/d...
 https://www.youtube.com/watch?v=k9ENEj33t4M construction video
This has been done for 3D models as well. https://brickify.it/
The idea was to build most of the model from Lego and 3D-print only the complicated / detailed parts.