Doing good portraiture is one of the hardest artistic challenges in drawing or painting and being able to do really good tattoo portraits is even more difficult. Not only is it a realistic art style, but a tattooist doesn't get the chance to reshade, change or fix the portrait as they are working on it. Any poor choices in shading or line work, and suddenly the portrait starts to not look like the person it's meant to represent.
Take for example, the tattoo shown here. It's a memorial tattoo, done for a girl who has passed away. Notice how bright eyes can quickly turn into a scary squint and how a happy smile can be rendered as a grimace. This tattoo picture is all over the internet, held up repeatedly as an example of what NOT to get for a portrait tattoo.Some things are easier to portray in portraits than others. Movie or cartoon characters where the image was originally drawn or designed fare much better than straight up portraits of people. Images of beloved pets also tend to come out much more accurately than images of people. If you truly wish to get a portrait tattoo, take the time and effort to seek out an artist who has made this form of tattooing their specialty and take a look at a LOT of their art before you make a decision.
I have a friend who has a tattoo on her leg of a mermaid and it was put there to honor her daughter. However, it's not an out-and-out portrait. At the time, her daughter was ten years old and my friend felt that her kid probably wouldn't want to see a childhood picture of herself from when she was little on her mom's leg for the rest of her life. The mermaid has the same haircut the daughter had at the time the art was inked so that it's a symbolic representation and not a literal one. Now, closer to twenty years later, both mother and daughter are still doing fine with the tattoo.
