HP revived the compact photo printer last year with the Sprocket.

This palm-sized device takes about a minute to bring your pictures - via Bluetooth - from smartphone screen to a physical, card-size (2x3-inch) photo.

You may wonder, who prints photos nowadays? In a move that would seem counter-intuitive at the time, but a stroke of genius in hindsight, HP targeted millennials in its marketing.

And it seems to have worked.

The Sprocket has been successful enough for HP to follow up with two other Sprocket devices.

The Sprocket 2-in-1 adds an instant camera so, in a pinch, you could do away with your smartphone camera, while the latest Sprocket Plus - which is reviewed here - upsizes the photos by 30 per cent.

It prints 2.3x3.4-inch photos. Like before, these photos come with an adhesive back so that the photo can be used as a sticker.

The cost of each printout has also been upsized. Each photo costs $1.05 ($21 for two packets of 10 sheets each) compared with 80 cents for the standard model.

The printer itself has a similar design.

The glossy white version - which is less susceptible to fingerprint smudges than the black version - has copper trim around its sides to make it less bland.

It is slightly thinner, but heavier than the original Sprocket. And it still holds only 10 sheets of Zink photo paper.

The real star of the Sprocket (and the Sprocket Plus) is the companion Sprocket app (available on iOS and Android) because the print technology is not new.

The HP Sprocket uses the same Zink technology as older compact photo printers, whereby a thermal print head heats up a special type of paper embedded with dye crystals to produce the image.

What makes the app stand out are the numerous filters and stickers that let users customise their photos with just a couple of taps on their smartphones.

They can also sign in to popular social-media websites such as Instagram, Facebook and Google to directly print their uploaded photos.

A new feature called Embedded Experiences augments the printed photos by adding a hidden watermark containing extra information from the original digital photo.

The idea is to give some context for the photo and help users relive the day the photo was taken.

To see what was embedded, you scan the printed photo with the Sprocket app.

For instance, it could play the source video if you had printed a video frame. It could also show related photos or videos recorded that day or the location the photo or video was taken.

The Sprocket Plus takes about one minute to print a photo, which is similar to the original Sprocket. Enabling Embedded Experiences will add some time to this process.

Print quality is, as expected, mediocre, with dull-looking images that lack detail.

But it is good enough for a quick instant snapshot where time and convenience are more important than fidelity.

Its 900mAh battery showed a 65 per cent charge after 10 prints. It is much improved over the previous model, which was at 20 per cent charge after 10 prints.

• Verdict: The compact HP Sprocket Plus makes the case that the best printer is the one you can carry with you.