A dedicated scan converter, such as a Robot 1200C or Tasco TSC-70, has a place to plug in a TV camera and all the necessary circuitry to capture the signal. Very easy.
However, none of the current PC-based SSTV systems have built-in circuitry to capture an image from a standard video source such as a VCR or camera. When using a PC-based SSTV system you need an additional device known as a Frame Grabber, Video Digitizer, or Image Capture Card.
For example, Digital Vision wrote the HAMCAP programs specifically for SSTV in response to customer demand. Here's how they are used.
When you click the TV Camera icon (in the paint tool box) or pick Digitize from the File menu, the system executes the commands in the DIGITIZE line of the configuration file. Let's look at an example.
DIGITIZE RUN="HAMCAP TG=DIG~TMP" OPEN=DIG~TMP.TGA DELETE=DIG~TMP.TGAThis runs the HAMCAP program and tells it to automatically capture an image from the camera and save it into a file called DIG~TMP.TGA.
Many command line options are available. For instance, "SV=1" means use S-video input instead of usual composite video. "PM=0" and "KY=0" will eliminate the preview mode and user interaction. Consult the documentation for descriptions.
Next this temporary file is read into the SSTV program and deleted.
The pictures don't look worse when read into Pasokon TV version 3. It's just that you have grown accustomed to the 640 x 480 images with 16 million colors so your expectations are now higher.
The solution is to use a newer version of HAMCAP that supports higher resolution and more colors. That way you don't lose anything when the image is copied to a temporary file.
FT=3This means save the image with 640 x 480 pixels and 16 million colors instead of the lower resolution default.