The photo I tested was just a simple portrait from about the 1880s. I was surprised how quickly it colorized, and I was pleased with how nice it looked but I realized that it actually just looked like a sepia tone had been added to it. I don't think that was the intention, and the skin tones did have a more fleshy color, but everything else looked like it'd just been sepia toned. A little disappointing.
Additionally, you may not be able to see it very well but this man's eyes were clearly light colored - blue, grey, hazel, etc. Something like that. But zooming in on his eyes shows the sepia/fleshy colors of the skin seems to have just been overlaid on his eyes, making them look brown, as if there was no attempt whatsoever to even color the eyes at all.
And while we're on the subject, they are beautiful eyes, aren't they? I've always thought this guy looks a bit like Leonardi DiCaprio.
To show you the difference between what a computer can do and what a human can do, here is my colorization of the same photo (including spot cleaning/restoration):
Back to MyHeritage. I then tried it with a group photo, thinking the multiple faces, garments, etc would add some variation to the possible colors. This was much more impressive:
Not bad for an automated system! Granted, the photo's highlights are a little blown out in places and some of the faces are blurred from too much movement, but colorizing system handled it pretty well in spite of that.
What's even better is that this is a high resolution image I used. I was a little worried that such an advanced tool available for free would only accept low resolution images (maybe charging for high resolution), but this was a fairly high resolution image and it not only accepted it, it still only took a few seconds to generate a color version. Unfortunately, although it will accept high resolution images, there is a limit to how many photos you can colorize if you have a free account. They don't tell you this anywhere but choose your photos carefully because you only get 10 of them, and deleting previous ones doesn't allow you anymore.
And the colorization still isn't perfect.
You may notice how it doesn't exactly take much risk or leaps with the colors it chooses. The men are in black suits, the women all seem to be in black and dark navy dresses, and the kids are all in white or neutral colors. You can probably understand why - I suppose they don't want a man's suit turning up bright red or something equally unrealistic for the era and gender. That's the downside to using a computer instead of a human who can distinguish these things and safely choose a greater variety of colors to apply.
Additionally, when I zoom in, there are areas that look like something almost resembling purple fringing except not along high contrast edges. You can see these sort of random purple splotches in the zoom-in below, particularly in her hair (pretty sure purple wasn't a trending hair color in 1880 Wisconsin), and sleeves. This is just a small area of the photo but these purple spots turn up everywhere if you look closely enough.
There's also some areas of the image that the computer seems to have some difficulty coloring. You'll note above how her one shoulder does not appear colored, or at least seems to be a different color from the rest of her dress - more of a sepia tone again. You see it most prominently in the skirt behind this child below:
At first, I thought maybe it was due to a shading variation in the original that may have fooled the system into thinking the difference in the shading meant a difference in color, but that is not the case. You can see in the original, there is no shading variation.
I guess the tool just sometimes has difficulty identifying edges and items so when it's unsure, it seems to do this. It's understandable, I suppose - after all, what is required to accomplish this in mere seconds must be an incredibly complex algorithm and coding, and it's provided for free, so I can forgive it for not being perfect.
Lastly, you may have noticed MyHeritage put their logo in the bottom right corner of the colorized image, and a little paint palette icon in the lower left. To avoid these, I'd recommend adding a superficial border to your image where the logo and icon will show up, which you can then crop off later.
I decided to try another photo (above), this time with more elements in it - horses, a house, etc to see if the same problems occurred, and they did. Once again, you can see all the clothing colors are very neutral. And again, you can see some weird rainbow-like discoloration at the top of the house.
And again, there were obviously some spots where the computer had difficulty colorizing or distinguishing between items - as you can see below, the hand on the shoulder looks like it either hadn't been colorized at all or it's blending in with the color of the other boy's jacket. Conveniently for the computer, it chose to "color" this boy's jacket grey!
So if you don't want any creepy dead hands like this, or your ancestors had blue eyes instead of brown, it's best to hire someone to do this for you instead of relying on an automated system. There are also Facebook groups with generous people who will colorize your photos for free, but be aware that Facebook doesn't easily support high resolution images like this does. This option from MyHeritage is still pretty impressive for what it is though, and if you're not bothered by the small problems that you might not even see very well when zoomed out, this will be amazing tool for many people. At the very least, I enjoyed seeing some color in the faces of my ancestors and relatives, as it seems to make them come alive a little more.
I haven't checked it out yet but there's an alternate colorizing option found at ColouriseSG. It appears to be free.