Why use an optical scanner rather than a video camera?
• Scanners can produce images of many times the resolution of a camera.
A good 2400 dpi scanner (true optical resolution) produces images which have 2400 by 2400 pixels per inch (2.5cm). Some can go up to 4800 dpi.
Over a scan area of 8.5 by 11.7 inches, it produces an image of 20 400 by 28 080 pixels (more for a LA scanner).
Over an area of 8.5 by 11 inches, unlike the scanner it still produces an image of 4272 by 2848 pixels. It has an equivalent resolution of approximately 350 dpi. The pixels are too large to measure very thin roots.
A good digital camera (12 Megapixels) can produce images of 4272 by 2848 pixels.
Therefore, you must reduce the area and take more images. The right scanner image is equivalent to 47 camera images!
• It is easy to get good images using a scanner.
Lighting is uniform over the entire scan area and it is not necessary to adjust the position, orientation or intensity of the light source. There are no focus or aperture rings to adjust.
• Calibration is permanent.
Unlike a camera, the object-to-camera distance and zoom are always the same.
• They are reliable and last for a long time.
When is a camera better adapted than a scanner?
A camera is better when extremely high magnification is required. By adding proper lenses or mounting it on a microscope, you can see more details than with a scanner BUT OVER A MUCH SMALLER AREA. Mychorizae and root hair are better analysed with such setups. A camera is also better when portability (like image acquisition in field) is required. WinRHIZO can analyse images taken with a camera with a means of calibration.
Can Regent’s scanners be used in the field or at a remote location?
Desktop scanners cannot be used in the field but are easily transportable and usable in remote locations where electrical power is available.
Not all scanners are created equal
The images below show the same roots scanned with two different scanners at the same resolution. As you can see, not only dpi (resolution) is important. The quality of optical, electronic and mechanical components have a great influence on what can be seen in an image (and hence, the precision of the measurements you make from it). Scanners are made for different applications, the graphics industry and home use being the major ones. Requirements for scientific usage are different. Eye-pleasing images are good, but it’s better to accurately reproduce reality. Therefore, before selling scanners for scientific use, we test them carefully to make sure they have minimal qualities. You cannot rely on theoretical specifications alone.
Target size is 5x5 mm
Why buy a scanner from Regent?
Although WinRHIZO can work with many scanner models that are TWAIN compatible, it is advantageous to purchase a scanner from Regent.
The model you buy has passed our scientific quality control test. You get a scanner that is well adapted (fast, precise and reliable) for long term repetitive scientific measurements. Before deciding which scanners to sell, we test many of the models available and we choose the best.
You get a scanner that has a dual lighting system which produces shadow-free images when scanning roots.
You get a scanner for which the TWAIN driver compatibility has been tested with our products. Unlike some other models on the market, our scanners support the dual light system recommended for WinRHIZO.
You are sure that our accessories will fit on the scanner. The root positioning system is specific to each scanner we sell.
We calibrate our scanners against precise standards to obtain more accurate dimensional measurements. This calibration is supplied with the scanner and is automatically used by our programs.
It is much easier for you to get technical support. You get competent and prompt technical support from people who not only sell the product but also use it. If problems arise, you don’t have to contact two vendors, only one is responsible for finding the solution.
You get our manual that illustrates how to scan biological samples for analysis with our programs (WinRHIZO, WinFOLIA...). This manual helps you to obtain the best images for accurate measurement and also gives some tips specific to the scanner that you have ordered.
Note: Regent Instruments does not provide technical support for scanners it has not sold, nor do we guarantee their compatibility with our products. In case of incompatibility, you can scan the images with the scanner manufacturer’s program, save them in tiff files, then open and analyse them in WinRHIZO.
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www.regentinstruments.com & www.regent.qc.ca
Last Revision November 2015