The market is changing rapidly and now high-resolution 320x240 pixel cameras are available at prices not much higher than the low-resolution models, giving the buyer a better choice
Probably the most important factor in choosing a thermal imaging camera is price.
But this should not be the only criterion considered in choosing a camera.
Buying a camera on price alone will almost certainly drive the buyer into selecting a low resolution, 160x120 pixel (or smaller) array model.
In many cases the user would quickly come to realise that important details were missing while performing thermography.
However the market is changing rapidly and now high-resolution 320x240 pixel cameras are available at prices not much higher than the low-resolution models, giving the buyer a better choice.
The next question, of course, is: why is high resolution important in thermal imaging? The answer: pixels are the data acquisition points for thermal measurement and are used to create a visual image from the thermal profile.
More pixels provide a more accurate thermal interpretation and higher resolution of the thermal image.
High-resolution is particularly important since it allows identification of smaller details in the image and consequently more accurate temperature measurements.
To make thermal imaging cameras more affordable to a wider market, many suppliers have introduced detectors with pixel counts of 160x120 and smaller, with or without interpolation.
However, their resolution is at best only one quarter that of a 320x240 detector, eg, 19,200 pixels vs 76,800 pixels.
These larger detectors produce images twice as wide and twice as high, with four times the data for the same field of view.
High-resolution cameras also allow users to work much farther away from a target without losing measurement accuracy.
To achieve good temperature measurement a target must cover at least 3x3 (9) pixels to be accurately resolved, otherwise the measurement will only be an average of the target and the background.
Low-resolution detectors interpolate a greater area between pixels and averages in temperature readings unrelated to the target.
For example, the temperature of a target can be measured as accurately at a distance of 10m by a camera with 320x240 pixels as a camera with a 160x120 detector at 5m.
Resolution in thermal imaging cameras affects temperature measurement accuracy, not just the visual image quality - a point often overlooked in choosing a camera.
A 320x240 detector with 76,800 temperature-measuring points can resolve an area of just 3x3mm at a distance of 2m compared to a 160x120 detector, with just 19,200 pixels can only resolve an area twice this size.
Plus, with more background averaged into the temperature readings, the measurements are inherently less accurate.
In conclusion buying on price may not be the best solution, particularly if accurate temperature measurement is an important factor.
It may be better to spend a little more to get the performance offered by a high-resolution camera.
Impac Infrared is a specialist in temperature measurement and consequently it offers only offer high-resolution thermal imaging cameras, it says.
With a choice of two portable models, the IVN 770-P and the IVN 320-P, the user can be assured of clear images and accurate temperature measurements.
In particular the new IVN 770-P represents a breakthrough in the cost of a high-resolution thermal imaging camera, offering high performance at a price similar to a low-resolution camera.
With a temperature range of -20C to 250C and on-board storage of upto 400 thermal images, the IVN 770-P is the ideal camera for both process and maintenance engineers.
