Manufacturers of today's production document scanners strive to deliver high quality images. One of the ways that they do it is by including built-in image enhancement hardware. Circuit boards on scanners take the original image and attempt to improve the contrast, clarity, and legibility of the image before it is passed to the host computer.
Once an image has been created on the scanner, it is sent to the "host" computer via a cable to a host interface. Some vendors offer scanner interfaces with built-in image processing. Additional image processing is applied after the image is received. Some of the hardware can even do rudimentary recognition of "patch codes" and bar codes in the short period of time before the image is saved to disk as a file.
Hardware-based image process during scanning has only a very limited amount of time to work on the image before the next image arrives. On an average production scanner that runs 60 pages per minute, this means just one second per image. On faster scanners, even less time is available. To really enhance the image, processing needs to be freed from any time constraints. Running images through software image processing modules after scanning is complete allows a lot more time to enhance the image through multiple passes.
Datacap scan software supports VRS (Virtual Rescan) and all hardware-based image processing. When more nuanced image processing is required, a separate Taskmaster task performs the honors. For maximum control, users can configure Taskmaster rules to sequence the image processing as required, perhaps first deskewing the image, then removing horizontal lines.
More recently, hybrid hardware technology is on the market that combines hardware on the scanner with hardware in the host computer. Kofax's VRS, is designed to maximize image quality over a wide range of input paper quality. It works with a card in the scanner that delivers the original grayscale image to the host computer, where the VRS-enabled hardware dynamically recalculates the threshold needed to convert the image to black and white.
A black and white image has one piece of information per pixel. Any enhancement involves deciding whether that images should be on or off. It is always possible that the "enhancement" ends up making the wrong decision about a pixel, resulting in poorer quality, instead of better. There is not much information to work with in this environment, which is why alternative strategies are used in products like VRS.
Datacap uses grayscale images, which offer 256 possible values for each pixel, as the basis of image processing. If the scanner delivers a grayscale or color image, then the software has much more information about each pixel to work with, before it needs to make a decision. The Taskmaster Grayscale Conversion Task takes grayscale images and then converts them from grayscale to black and white.
Similarly, the Taskmaster Color Conversion Task takes color images and converts them to grayscale or black and white.
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