We do not often recommend HD-SDI cameras because there are shortcomings with the current technology a topic for another discussion. High resolution megapixel cameras are fantastic and are becoming more affordable. And keep in mind that the higher the resolution of the cameras, the more bandwidth and hard drive space you will need to transfer and store it. The other issue to know about the human eye has to do with frame rate.
The human eye can perceive about 15 separate visual images per second frame rate. So any frame rate higher than 15 frames per second fps is perceived as smooth motion. But anything over 15 fps is going to look pretty good. Some devices will list different resolutions at different frame rates. In a CCTV application you will have many cameras with different resolutions but usually only one recording device.
So make sure that the recording equipment you choose has at least the resolution capability of your highest resolution camera. The shots from the megapixel camera have slightly greater potential for enlargement, however. Equally important is the size of the actual photosites on the sensor that collect the image-making light.
Details of how to calculate the size of sensor photosites are provided below. As you can see, the sensors used in digital SLR cameras are substantially larger. This is important because the more light each photosite collects, the less the signal has to be amplified to produce an image and the better the image quality will be. The actual calculation is straightforward. Simply divide the length of one side of the imaging area by the number of image pixels that correspond to that side.
Dividing the width of the sensor 5. The table below shows a range of typical photosite sizes for current consumer digicams in red and DSLR cameras in green with typical examples for each resolution category. The more photons collected, the more information the camera can process — and the less the image is affected by the background noise that is generated by all electronic devices, which is relatively constant.
The diagram below illustrates why larger photosites are less affected by noise than smaller photosites. But the amount of background noise is the same for both photosites. Consequently, the larger photosite has a much better signal-to-noise ratio. It can also collect more light with the same exposure time and, therefore, respond with higher sensitivity. Identifying Image Noise In most cases, noise can only be seen when the image is enlarged substantially — at least times.
Sometimes you may see a pattern of tiny white or coloured dots, scattered randomly throughout the image. Noise also reduces the sharpness of edges between bright and dark areas in the picture and can make it look unsharp and a little flat. Get emails, once a day, Monday to Friday. Most applications are fine with 12 frames or less, which is quite typical for 3MP cameras. While a lot of attention will be drawn to 'full frame rate', the reality is surveillance applications have traditionally used far fewer frames per second and been successful at doing.
On the other hand, there will be certain applications like casinos or money counting where milliseconds count. A 12 frame per second camera provides an image every 83 milliseconds; A 30 frame per second camera every 33 milliseconds. An HDTV camera cuts out 50 ms. Only in circumstances where very fast tiny movements are key will HDTV make a difference. Of course, it's just trade shows but it's reasonable to assume that not all companies who market HD cameras are going to produce the same quality.
So far the p HD cameras are being priced at a significant premium to traditional 3MP cameras. Contrast this to an Arecont 3MP H. To view the videos, please enable JavaScript in your internet browser.
0コメント