How to pick an embroidery machine
It isn't the machine selection that matters so much as the software available for a particular machine and the ability of that software to digitize a photographic image into the the correct form.

My sister has a couple machines with which I've assisted in the software on multiple instances. One in particular was the conversion of a photograph of a fluffy dog to an embroidery file.

The software supplied with the machine varied depending on the price paid. She purchased a more-deluxe version and it had the image digitizing feature. 

Be advised that photographs are quite complex and can result in thousands of stitches of various colors. For a single needle machine it will also result in that many changes of colors of threads. Obviously, the number of thread changes will be reduced by a factor directly associated by the needle count.

Resolution is going to impact your job size as well. The lower resolution image will "print" faster, with fewer color changes.

The aforementioned fluffy dog was reduced to black and white and became somewhat blocky, but was still recognizable as the dog of the person receiving the gift.

The price differences for one machine to the next will have to do with the capacity of the computer controlled hoop, the overall speed, the additional features (wifi, display size, etc) and the number of needles.

Our area (USA) has many sales representatives within retail shops who are frequently happy to sell machines and talk them up a good bit. You will also find it valuable to frequent the forums specific to a machine you are considering and view the problems, questions and solutions others have posted.