How to pick an output format

Before choosing the ScanToNotes or ExperScan output format, ask yourself the following questions:

1. How good must the color rendition be?

2. How fast will the documents be scanned in?

3. How does my choice influence file size?

In order to answer these questions, you must understand some technical definitions:

Bit Depth: The basic unit of image information is the pixel (picture element) which contains the information for one point of the display. To store the information for 1 pixel, the computer might need 1,4,8, 16 or 24 bits. The number of bits stored per pixel is the bit depth.

Resolution: The number of pixels stored per inch is the resolution (horizontal or vertical). This is usually measured in dots per inch (dpi).

Compression: Instead of just storing the raw pixels of an image, the computer can look for patterns and represent the patterns with fewer bits than the original. This is called image compression. ImageSuite makes use of several standard compression algorithms. Of course, the image viewer program has to understand these algorithms.

How good must the color rendition be?

Choices here are black and white (bit depth 1) or color with 16, 256, 65k or 16 million different colors i.e. bit depth from 4 to 24. To save space and speed processing, choose the lowest bit depth that meets the visual reproduction standards of the application. Lower bit depth will also compress better.

How fast will the documents be scanned in?

The more bits, the scanner has to capture per pixel, the slower it will scan. For common desktop scanners, scanning at 24dpi can be painfully slow. Again, choose the lowest bit depth that meets the color rendition requirements.

A second factor is the scanning resolution – the higher the resolution, the more pixels have to be captured and the slower the scan. A common scanning resolution is 200 dpi. The resolution choice should take into consideration the most common use for the image. Screen resolution is typically 72dpi while printers usually default to 600 dpi. So images destined to be printed should have higher resolution.

How does my choice influence file size?

As discussed above, higher resolution and greater bit depth lead to bigger files. File size will be reduced by storing the files in a compressed format.

TIFF with group 4 compression is an industry standard format that does an excellent job of compressing using a two-dimensional algorithm and is highly recommended for black and white documents. On the downside, TIFF images are not supported by Internet Explorer, the user will need a separate viewer.

JPEG is a popular compressed format for color images. JPEG's compression is not perfect and some image detail is lost in JPEG images.

PNG is an open standard for color images. It does not lose detail in its compression and can be viewed in browsers and most viewers.