Interpolation of megapixels in camera traps
One of the first things that often comes to mind when comparing trail cameras is the number of megapixels, the idea being 'the more megapixels, the better the image quality'. Wildlife camera manufacturers cleverly capitalise on this by interpolating the number of megapixels (see box below) and then advertising these interpolated megapixel values. However, the true sensor resolution is rarely reported, while in fact it says much more about the image quality of the camera.
Interpolation is the derivation of new data points within the range of a set of known discrete data points under the assumption of some relationship between them. Concretely, in the case of trail cameras and megapixels, this means that the software in the camera tries to make, for example, four pixels out of one actually measured pixel. The colour of these four new pixels is determined on the basis of the colour of the immediately surrounding measured pixels. Although there are forms of good interpolation, it is a myth that this increases the quality of the image. Interpolation remains an adaptation of the actual measured image. In fact, interpolation is often accompanied by more digital noise and colour shifting. It also leads to more data storage and battery consumption.
Videos are not as easy to interpolate as photos, but manufacturers have also come up with clever marketing tricks for this. For example, there are several cameras on the market today that have a 4K Ultra HD video resolution. This sounds very good, but in reality, this resolution is only achieved with a frame rate of 15 frames per second (fps) for most models. This while Full HD cameras usually have a frame rate of 30 or even 60 fps. The number of frames per second says a lot about the quality of the video image. A higher number of megapixels or a higher resolution of the video images does not always mean better images. So always try to pay attention to the frame rate of the videos at the different resolutions. Sometimes it is nicer to set the camera to Full HD resolution than to 4K resolution. In any case, the best advice is to base your opinion on practical examples. That is one of the reasons why we at WMS are currently very busy collecting realistic and reliable practical footage of all our cameramodels, so that we can make this available to you on our new website!
Adjustable image resolution | What to choose?
With many camera traps, the image resolution is adjustable for both photo and video. By adjusting the resolution to your desired target, you can make efficient use of the battery life and storage capacity of your trail camera. The highest possible resolution may be unnecessary, for example, if you only want to demonstrate the presence of an easily identifiable species. You are also aware of the fact that a higher image resolution does not always result in sharper and better pictures. In fact, a higher image resolution often results in a slower shutter speed, with the possible result that a moving animal will appear blurred on the photo. A higher image resolution can be especially useful when observing small, less identifiable species. The advice is therefore to experiment a lot with the different resolutions that your camera offers in order to find the best settings for your application.