Video Monitor Image Capturing

This page is a tutorial on how to digitize images with a Macintosh computer (many models have a digitizing card or one can be bought) and how to prepare them for use on the World Wide Web. This page covers:

Digitizing Images

Step by Step Hardware Setup

Find a video source: live camcorder, VCR tape, TV, cable feed, or videodisc. Prepare ahead of time for your computer session by logging your video sources so that you can find images efficiently when you come to the computer. Remember to consider issues of copyright and have written permission for images you wish to broadcast over the network using your Web browser, such as Netscape, if they come from copyrighted work.

Check your workstation's hard drive space and make sure you have a few spare magabytes to store your work. If so, then create a temporary folder for your images on the desktop and as you digitize, put the images that you wish to keep in there. You can use the GIF Converter program as a slide sorter, displaying many images at the same time from your folder, and cull your collection periodically. Bring plently of spare diskettes, but a SCSI cartridge hard drive or tape backup system is preferred. Then when you quit, after making sure that you have a copy of the day's work on your own disk system, drag the temporary folder to the trashcan.

This is an issue of etiquette. Please make sure that your work is removed from the workstation when you are ready to leave the lab, as images take up large amounts of space and will have to be deleted by someone to make room for the next person.

Connect your video output to the video input of the digitizing card on the back of the Mac. At the moment there are several PowerMac stations and one Quadra 660AV station. The PowerMacs have two RCA adaptors with connectors hanging off the back of the case. These adaptors are marked input and output in the plastic and must match the input and output marking in the digitizing card on the back of the Mac. If you are using a device with an S-Video plug, remove the adaptor and use the S-Video connection in the place where the adaptors were plugged. The quality of your video signal will be improved.

Watch your powercord wires running from your video source and arrange them to reduce the likelihood of someone tripping over them as they pass your workstation. Make sure all devices are powered on.

If you are shooting an image on paper with a camcorder, use extra lighting sources (e.g., the copy stand). You may need some tape handy to tape images to the wall. For higher quality, mount your camcorder to the copy stand and use a glass plate to press paper flat.

Step by Step Software Procedures

Assuming that your hardware is properly configured and connected and a video feed is being sent to the Mac, find and run the program that ships with AV Macs called Video Monitor, or Avid VideoShop or some other digitizing program.

  • In the Instructional Technology Center, the program can be found quickly on the launcher screen. Once this program is running, it places a window displaying the video feed on the screen.

  • Check preferences under the pulldown menus. You can either save your images directly to disk or save it to the clipboard and paste it into another application as you go. I have often used the ClarisWorks draw program, pasting each image on the clipboard to a draw file (up to 6 small images works well) and then saving them to disk. For preparing images for the Web however, saving them to the desktop seems most efficient for me.

  • Check your screen size and set it to one of its three sizes. The bigger your image, the longer it takes to transmit and the more storage space it takes up, so consider this carefully.

    Let's assume that you have set Video Monitor to save your images to the desktop. When you see an image that you wish to digitize, hold down the Command (Apple symbol) key to left of the space bar and tap the letter C (for copy). A couple of seconds later the image is digitized and visible as a file icon on the desktop. Double click on this file and the Teach or Simple Text program will display this image. If the image is acceptable, drag it into your temporary folder. If not, drag it to the trashcan. If you are taking slides/images from a rolling video tape in this manner, you may have to press the Copy keys (Apple C) slightly before you see the image or frame that you really want. This timing will take some practice. It is generally only a problem when trying to digitize a particular moment of a smile. Different programs will use different command keys and symbols to activate the digitizing. Study the program you have and its help files and you will find them.

    When you have a number of images digitized you will need to cull through them. Find and start up the GIFConverter program and Open several of the images in your folder in the numbered order in which you shot them. Just keep going to the Open command until to have opened what you need or can display on the screen. Drag each new image alongside a previous one. Since you can make side by side comparisons of several shots at the same time, you can quickly decide which ones to keep and close and drag the rest to the trashcan and empty it.

    Any image that is destined for the Web must be saved in a different file format than PICT. The image file comes into GIFConverter as a PICT file because that is the format used by the Video Monitor program. To change the format, move to save the file and in the Save As dialog box, click the term PICT near your file name. This will open a pop-up window with a choice of other file formats. Select the GIF format. This should append a .GIF extension on the file name. If it does not, place it there manually. Note carefully where you are saving this file and place it appropriate to your needs.

    Notes on irregularities

    Even though the GIFConverter application saves files with the extension of GIF, the server or the browser can be case sensitive and not recognize the files until the image is typed in lowercase, eg., .gif. This is not supposed to be the case, but changing it has made some images accessible on older browsers.

    Some models of PowerMac AV's are very sensitive and erratic in their image digitizing capacity when the monitor is hooked to the motherboard. Make sure that the monitor has the adaptors to hook directly to the digitizing card itself.

    Other Image Sources

    For obtaining original image work, there are a number of tools: For obtaining previously prepared copyright free images, find:

    Digitizing Rolling Video

    Digitizing rolling video into short videoclips can also be done with the Macs, but cannot be done by Video Monitor. Instead you will need to use Fusion Recorder, VideoShop or other software which is available on many Macs in our facilities. See the help data within those programs. Once saved, these files will also need the correct suffixes so that the browser and server software can handle them properly.

    Houghton@wcuvax1.wcu.edu

    Copyright Notice - Dr. Robert S. Houghton, Copyright, 1994-6.

    Houghton@wcu.edu