PowerPoint and Image Considerations

"If I had to choose, I would rather have birds than airplanes." Charles Augustus Lindbergh

Life is full of choices. Even when using tcConference technology, there are choices to be made.

This article will discuss some background information on Internet bandwidth and image resolution, and then talk about available options.

Internet Bandwidth:

Internet bandwidth, or Internet speed, is the size of the "pipe" available to transfer data from one computer to another. An appropriate analogy might be that of filling a gallon bucket with water. A 1/2-inch pipe might take as much as 30 seconds. On the other hand, a 2-inch pipe could well fill the bucket in 2 seconds. The bigger the pipe, the faster the task would be completed. Engineers talk about Volume Flow, measured in gallons per minute, to describe the volume of water that can be moved from point A to point B. Similarly, the term Kilobits Per Second (kbit/s) is used to specify the volume of data moved from one computer to another. Dial-up services typically provide up to 56 kbit/s - a small "pipe", while ADSL and Cable services can provide a "big pipe" that may be more than 100 times faster. For perspective, it takes approximately four and a half minutes to download a two-megabyte file on a dial-up connection. The same file will download in about five seconds with a high speed ADSL or Cable connection. Some providers offer a "Lite" ADSL or Cable service that is just 5 to 10 times faster than dial-up. The download times indicated here are the "theoretical best". Factors such as Internet congestion, the physical quality of the connection, and a variety of other factors can degrade the service, resulting in performance that may be less than ideal.

Image Resolution:

Image resolution refers to the sharpness and clarity of an image. In the case of a printer the resolution indicates the number of dots per inch (dpi). For example, a 300-dpi printer is one that is capable of printing 300 distinct dots in a line one inch long. A photograph, whether viewed on the screen or printed, is composed of tiny dots - also called pixels. The number of these dots that fit into a one inch space specifies the resolution - the higher the number, the sharper the image resolution. This sharper image, however, requires a larger file AND a longer time to transfer to another computer. For a display, the screen resolution signifies the number of dots (pixels) for the entire screen. Therefore you will see a display with a resolution of 800 x 600 - 800 dots across the top and 600 dots vertical - or 1024 x 768 and so on.

One important point to recognize is that a 17 inch display with a resolution of 1024 x 768 has a dpi resolution of about 80. Therefore any image with a resolution more than 80 is wasting Internet bandwidth if is only sent to be viewed on a display.

PowerPoint:

PowerPoint is an excellent tool for creating powerful presentation material. The slides created with PowerPoint may contain many different types of objects such as images and special text. Because some of these objects (such as images) can be very large, care must be exercised when such a PowerPoint presentation is "pushed" via the Internet. PowerPoint (Version 2002 or later) provides a formatting function by which a single image (or all the images in the presentation) can be compressed to a resolution of 96dpi - a value suitable for Internet use. To utilize this function, select any image, click the Format/Picture menu, then activate Compress and follow the prompts. Make sure you select the "Compress All Images" option.

PowerPoint is designed to be used directly from a Computer. In its "raw" or "native" state, it does not work well when pushing slides in a web conferencing environment. However, tcConference technology provides a utility to convert the presentation into HTML, GIF or JPG formats, all of which are suitable for web conference use. The same utility (found by accessing the Administration drop-down menu and then clicking on Document Center) is available for upload of the presentation to a web space for immediate use in a web conference meeting.

The obvious question is: "What format should I use?" If you are going to use the presentation slides with the Whiteboard (also provided with tcConference technology), there is no choice: it must be converted to JPG or GIF format. Choosing GIF or JPG is a matter of personal preference. Also, if the uploaded presentation is going to be used outside of the web conference room with any browser other than Internet Explorer, either the JPG or GIF option should be used.

If the presentation is going to be used only as a web presentation, any of the HTML, JPG, or GIF formatting options can be chosen. Your objective should be to make the converted PowerPoint files as small as possible while still maintaining the highest quality possible. Remember that you are not only going to be pushing these slides to your audience, but you will also be, simultaneously, be speaking to your audience. Both audio and pushed slides require bandwidth. If you are sending a large image file, it will take some time to push that file. This will particularly be the case if you or any of your audience is using dial-up connections. More importantly, the audio quality will be negatively impacted due to the delays imposed by tranfer of large images.

If you have a version of PowerPoint that will compress the images, the recommendation is to use that function, then save the presentation, and choose the HTML formatting option. The resulting conversion, except in rare occasions, will have the optimal file sizes, and will certainly look more professional.

The following example will show a presentation slide that was converted using the HTML format. The file size is 40K. Click to view After viewing, click the Back button on the browser to return.

The following example is the same presentation slide that was converted using the JPG format option. The file size is 58K. Compare the text at the bottom and top of both examples. Click to view After viewing, click the Back button on the browser to return.

In this case the HTML converted document is superior, smaller in size, better quality, and therefore the better choice.

If you have a older version of PowerPoint, an image editor can be used to change the resolution of images before you insert them into PowerPoint; if you don't wish to do that, use either the GIF or JPG formatting option.

Talking Communities strongly recommends that you experiment with the different options, and then choose the option that works best for you.

Tips:

• Always compress all images.
• Use images carefully ... be wary of using large/many images.
• If you have a page of text with some supporting images, the temptation may be to simply scan the entire page, and then insert the resulting image into the presentation. Seriously consider retyping the text and inserting just the images where needed.
• View the presentation through your audience's eyes. Far too often we get carried away with our own creativity (!) and create presentations that are too long, too complex, or (worse) both. A rule of thumb is to allow at least 2 to 3 minutes per slide - 20 to 30 slides for a one hour's presentation.
• A page of text that has been scanned is an image, not text, and will be considerably larger than if the same information were typed into the presentation. Consider finding the original text document and pasting that information into the presentation or retyping the text into the presentation.
• ALWAYS test your presentation completely before going live.
• Run through your presentation, from beginning to end, before turning on "Follow Me". This will load all the slides into your computer's buffer area.
• A "quirk" with PowerPoint is, if the size of an image within PowerPoint is changed, a new image will be created and both image files will be retained. Subsequently, when the presentation is converted with the HTML formatting option, both images files will be uploaded and used. This happens when there has been a significant change in the size of the image - "significant", unfortunately, cannot be defined. The only way to remedy this issue is to copy the image file, resize the image (using an image editor) before inserting the image into the presentation. This is a "pain", but it may further reduce the size of the converted presentation files - if that is needed. This is normally a concern only when the original image is large and the resized image is much smaller.