                Opening and Saving DVA Images
                -----------------------------

Using ImagePrep/Colorlab you can now open and save images in 
VideoLogic DVA format. To display DVA images, you will need the 
DVA-4000 digital video adapter and the MIC System II software. 
The DVA-4000 is a full-motion digital video adapter, available for 
IBM PC-XT, PC-AT, PS/2 and Apple Macintosh computers. DVA images are 
saved in VideoLogic's proprietary 21 bit YUV format.

Note that, when opening images saved with earlier versions of the 
MIC System software, you will need to specify the .IM4 suffix 
used for these files.

When saving an image in DVA format you will be given the 
following options:

Video Resolution (Field or Frame)
---------------------------------

The DVA-4000 displays each video image as a sequence of two 
fields. Using the MIC commands, you can choose to display either 
or both fields of a video image. As a general rule, images 
displayed in Frame mode (showing both fields) contain more 
information than images displayed in Field mode (showing a single 
field), but, in some cases will suffer from a flickering effect 
caused by the difference in the content of the two fields. You 
will need to experiment with these settings to find the best 
result for your particular application.

When converting an image to DVA format, you should choose Field 
or Frame depending on whether disk space or quality is at a 
premium. Images stored using the Frame option are nearly twice as 
large as images saved as a single field -- typically 350K as 
opposed to 175K for a 640 x 480 image. However, if an image has 
more than 241 vertical lines (284 in the case of PAL), saving it 
using the Field option means that some information is lost in 
order to fit the image into a single field. The difference in 
quality with most images will be minimal, but will be most 
apparent with larger images.

Video Standard (PAL or NTSC)
----------------------------

Select the video standard you are using for live video input. 
This is not critical. You will be able to display images saved in 
PAL format when running live video in NTSC and vice versa. 

NTSC images have 241 lines per field (482 per frame) and PAL 
images have 284 lines per field (568 per frame).

Graphics Card (VGA, Super-VGA and Macintosh)
--------------------------------------------

Different display systems use different horizontal scaling, so 
you will need to select the type of graphics card you will be 
using to display the DVA image. Choose one of the following:

VGA
for DVA systems used with standard VGA cards in 640 x 480, 16 
color mode and Super-VGA cards in 640 x 480, 256 color mode.

Super-VGA
for DVA systems used with Super-VGA cards in 1024 x 768 
interlaced, 16 and 256 color modes.

Macintosh
for DVA systems used with Macintosh 640 x 480 graphics cards.
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