When purchasing a scan converter, there are several variables that can make a significant difference in whether you will be happy with your purchase or not. Since the role of the scan converter is to convert computer video into television video, both the computer and the television being used will have an impact on the results. Television products such as the TV, video cameras, VCRs etc. all operate at a frequency (scan rate), of 15.75 kHz which keeps them compatible with each other. However, computers are not as standardized and can operate at 15.75 kHz to frequencies that exceed 100 kHz. The higher the frequency, the better the image quality. Hence the need for scan converters.

As would be expected, the higher quality scan converters with the most features also have the highest price tags. Before going too far into the selection process, determine your expected usage and budget to avoid paying for whiz bang features you may or may not need. The type of technology used in the conversion process is generally the driver of the price and the quality of the output.

On the lower end is the software driven converter. These scan converters use software, generally on the video card of the computer, to aide in the conversion process. During the conversion process, every other line of the image pixels is eliminated. As you can imagine, this results in a lower quality in the image output.

Mid-range scan converters use a more sophisticated method of digital pixel sampling before eliminating pixels and have many more enhancement options available. The conversion process occurs entirely within the scan converter rather than using external software, and results in a higher output quality.

On the high end of the spectrum, a digital pixel sampling is still utilized in the conversion process, however, it is completed at a much faster rate and with much improved accuracy. These models also provide additional features for image manipulation, resulting in an output that more closely matches the original image than other lower cost options.

With your needs and budget in mind and a basic understanding of the cost drivers, you are ready to begin looking at specific models. Keep the following questions in mind as you make your final selection.

1. Is my computer display mode supported?

Lower end scan converters may only support computer resolutions of 640 x 480 and although this is often the default setting on computers, many people increase their resolution settings and the lower resolution may not be considered acceptable. You will also want to make sure the check the compatibility of the vertical refresh rates.

2. How many colors does the scan converter output?

Most modern computers and televisions can support 24 bit color so it makes sense that you would want a scan converter that can input and output 24 bit color. Not all scan converters process and output 24 bit color. Be sure to check that the 24 bit color is not only supported, meaning it can be accepted as input, but that it can also be processed and output if color accuracy is important to you.

3. Does the scan converter allow for manipulation of sizing and position of the converted image?

On a computer monitor, the picture does not always extend to the edge of the screen. On a TV, the picture extends off the screen. This discrepancy can make displaying a computer image on a TV screen problematic. Some scan converters allow for manipulation of the converted image to fix this issue using “underscanning” where it shrinks the picture horizontally and vertically. Higher-end scan converters allow for other options such as pan and zoom, and a cropped output.

4. How is flicker reduction managed?

When evaluating a scan converter’s flicker reduction feature, be sure to examine both converted images and text. Although many low-end scan converters can eliminate all flicker, this is not always a good thing. For example, when all flicker is eliminated from text, the text can become unreadable because of the information that has been removed. Some scan converters have a single level of flicker reduction, which is either on or off. Others have multiple or continuous levels of anti-flicker controls for the optimal effect.

5. Does the scan converter offer built-in genlock with timing?

Genlock allows the user to use the converted output in sync with another video source allowing the two video outputs to be edited together. Check to see if the scan converter offers easy-to-use controls to adjust both the horizontal and subcarrier phasing, which is the timing, if you plan to use the output in other projects

When considering any scan converter, be sure to view samples of the output to be sure they are acceptable for your intended usage. If possible, observe the converter in operation. The manufacturer warranty and reputation are other key factors that should not be overlooked.

For further assistance in selecting the best scan converter for your situation, contact the AV Superstore staff. They will provide knowledgeable guidance in your selection process.