For some time, many paint stores have offered a service that matches paint to the colour of an object you take to the outlet.

That's fine for easily portable items, but what if you want to match a colour that's already on your wall (eg, in existing wallpaper)? Or perhaps you want to paint the legs of a desk to match a filing cabinet?

Colour measurement devices have been out of reach for non-professionals, but paint brand Taubmans has come up with an affordable system that lets practically anyone generate paint codes that match existing colours.

The key part of the system is the Coloursmith app, available for iOS 8 or later, and Android 5.0 and later. It uses new or stored photos as the source.

If you don't have a phone or tablet that can run the app, you can upload a photo to the Coloursmith website and extract the colour of interest.

The limitation is that the analysis cannot be calibrated to the specific digital camera used or the lighting conditions.

So the next step up is to use the $5 Coloursmith Window. This is a credit card sized colour target with a square hole in the middle. You place the card over the object you're scanning, and line up the phone so the card fills the designated area on the screen. Once the app is happy with your alignment, it takes a short series of photos. Coloursmith 'knows' what the colours on the target are, so it can adjust the image accordingly.

The Coloursmith Window also features some embossed areas that help adjust for the way the light is falling on the object, and it did result in more accurate colours, at least as rendered on the phone's screen.

Last, and most expensive (though cheaper than comparable products) is the $195 Coloursmith Reader hardware device, which is made for Taubmans by Variable, a specialist manufacturer of portable colorimeters and spectrophotometers.

It comes in a convenient padded case that also contains a calibration tile and a short USB cable for recharging.

According to Variable, the Coloursmith Reader uses multiple illuminations representing sunrise, noon and sunset daylight, and incandescent and fluorescent lighting, as well as compensating for gloss and surface texture.

Once the Reader is connected to the phone via Bluetooth, you touch the app's Match button, then the Coloursmith button, place the device on the object to be measured, and touch another Match button. A few seconds later, the app presents its interpretation of the colour.

Sometimes that's a single colour, but you're often presented with a choice of three or more shades where the Reader is for some reason unable to make a precise determination.

According to the instruction leaflet, it's supposed to be possible to initiate the matching process by pressing the 'wake' button, but that didn't work in our testing. The closest it came was to display a notification on the phone that the device (which was identified as "Muse SCI-xxxxxxxxxxxx") wanted to open the Coloursmith app. Apart from that, nothing happened even if the app was active.

A pleasing touch is that the ring of LED lights on the top of the Reader don't just show the device's status as described in the instructions (eg, flashing red means it's time to recharge, slow flashing blue means it's paired with the phone), but it also changes briefly to an approximation of the scanned colour. It's not especially useful, but it made us smile – and that's a good thing.

Less pleasing is the way the Reader takes about 20 seconds to reconnect to the phone. It's quick to disconnect, so this delay can be quite irritating unless you have everything ready to measure multiple colours in quick succession.

How closely the colour appearing on the screen matched the original object was quite variable. Some shades appeared spot on, while others – especially browns – seemed to deviate significantly.

For example, scanning a chocolate brown from a historical colour chart with the Reader gave a much darker shade, while the result when using the Window looked much closer to the original.

Using the Reader, a reddish stone shade looked somewhat purple, yet a related grey-brown colour was reproduced relatively faithfully on screen. However, repeated scans gave consistent results. It's worth noting that if you scan the same colour twice, you don't get duplicate entries in your palette.

Scanning a variety of objects including a painted wall, a filing cabinet, a towel, a pottery jug and some upholstery fabric gave convincingly close results, even though the degree of glossiness varied widely.

But the proof isn't on the phone, it's in the paint. So we ordered sample pots of the two stone shades to see how they came out.

This photo shows the colours as shown on the colour chart (above) and the paint (below; please excuse the pronounced brush marks!).

As you can see, the results are impressive. In direct sunlight or under fluorescent light they look even closer than they appear in the photo, which resembles what we saw under warm white LEDs. Incandescent lighting gave the biggest differences between the paints and the reference source. Even then it's important to realise that they appear as slightly different shades of the same colour – you don't perceive them as being mismatched, as sometimes happens when rely on your memory of a colour when buying decor items.

Sample pots can be ordered through the app, or by taking the phone to a retailer where the QR code for the shade is scanned from the screen. Online orders are restricted to low sheen – it's not clear whether other finishes such as gloss are available in store. There's also a price difference: online orders cost $5.20 for a 100ml pot (post free if you order four pots), whereas Bunnings charges $5.73 for 250ml sample pots.

Once you're happy that the colour matches, buy the amount of paint you need for the job by presenting its QR code at the counter.

In our testing, the Coloursmith Window worked well, and at $5 it's a no-brainer. For just over a tenner you can buy the card and a sample pot, then check the paint against the original before spending more than $70 on a four litre can of paint.

And if you're someone who redecorates according to fashion or 'just for a change' rather than out of necessity, the extra cost of the Coloursmith Reader would soon be amortised over several projects – assuming you're the sort of person that wants or needs to match existing colours.

The Coloursmith Reader and Coloursmith Window can be ordered via the Coloursmith web site or purchased at Bristol, Bunnings and Taubmans stores.