PowerPoint and Image Considerations

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

Life is all about choices. Even with the use of PowerPoint, you have choices to make when employing tcConference technology.

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

Internet Bandwidth:

Internet bandwidth, or Internet speed, is the size of the "pipe" available to transfer data from one computer to another computer over the Internet. As an analogy we could look at filling a one-gallon bucket with water. If we needed to fill the bucket and we had a half inch pipe, it might take about thirty seconds. If we had a two inch pipe, it our bucket might be filled in just two seconds. The bigger the pipe, the faster we could complete the task. 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. We use the term Kilobits Per Second (kbit/s) to specify the volume of data we can move from one computer to another. Dial-up services typically provide up to 56 kbit/s - a small pipe, while ADSL and Cable services are up to a hundred times, or more, faster - a big pipe. To put that in perspective, it would take approximately four and 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 five to ten time faster than dial-up. The download times (as suggested above) are the theoretical best times. Internet congestion, the physical quality of the connection, and other factors can degrade the service and, therefore, the performance can be less than optimum.

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 determines the resolution - the higher the number of dots, the sharper the image resolution, necessitating a larger file; the larger the file, the longer it takes to send the image to another computer. For a "display", the screen resolution signifies the number of dots (pixels) for the entire screen. Therefore you will see, for example, a display with a resolution of 800 x 600, meaning there are 800 dots across the top and 600 vertical dots. Or, a display may be 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 effective material for powerful presentations. The slides created with PowerPoint may contain many different types of objects such as text, images, and so forth. Because some of these objects (images, for example) can be very large, care must be exercised when the presentation is distributed via the Internet. PowerPoint version 2002 (or later versions) provides a formatting function to compress a single image (or all the images) in a presentation, to a resolution of 96dpi - a value suitable for Internet use. To use this function, select any image, click the Format/Picture menu, click Compress and follow the prompts. Make sure you select the "Compress All Images" option.

PowerPoint is designed to be used directly from a source computer. In its "native state", PowerPoint does not work well when pushing slides in a web conference environment. However, our web conference 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 in Administration/Document Center) will upload the presentation to a web space so it can be used in a web conference meeting.

The obvious question is: "What format should I use?" Let's start with the simple answer first. If you are going to use the presentation slides with the Whiteboard (also provided with the 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, please note that if you are going to use the uploaded presentation outside of the web conference room, with any browser other than Internet Explorer, you should use the JPG or GIF option.

If the presentation is going to be used simply as a web presentation, you may choose the HTML, JPG, or GIF formatting options. Your objective should be to make the PowerPoint-converted files as small as possible while maintaining the highest quality presentation. Remember, you are going to be simultaneously speaking AND pushing these slides to your audience. Both the audio and the pushed slides will require bandwidth. If you are sending a large image file it will take some time to push that file, particularly if you, or anyone in your audience, is using a dial-up connection. Moreover, you do not want to negatively impact audio quality as a result of such "imposed delays".

If your version of PowerPoint will compress images, our recommendation is that you compress the images, save the presentation, and then choose the HTML formatting option. The resulting conversion, except on 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 HTML format. The file size is 40K. Click to view After viewing, click the Back button on the browser to return to this article.

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 here.

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

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

Our strong recommendation is that you experiment with the different options, and then choose the option that works best for you.

Tips:

• Always compress all the images.
• Use images carefully - use smaller images and don't be too generous with the number of images.
• If you have a page of text with some supporting images, you may be tempted to simply scan the entire page, and then insert it as an image into the presentation. Consider retyping the text and inserting just the images you absolutely need.
• View your presentation through your audience's eyes. Far too often we get carried away with our own creativity, and construct presentations that are too long, too complex, or both! A rule of thumb is to allow at least 2 to 3 minutes per slide - 20 to 30 slides for a one hour presentation.
• A page of text that has been scanned is an image, not text, and will be considerably larger than if the same information was typed for the presentation. Consider finding the original text document and pasting that information into the presentation or retyping the text into the presentation.
• 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 which can happen is, if you change the size of an image within PowerPoint, a new image will be created and both image files will be kept. When this presentation is converted with the HTML formatting option, both image files will be uploaded and used. This happens when there has been a significant change in the size of the image - the meaning of "significant" is anyone's guess! The only way to remedy this is to copy the image file and resize the image (using an image editor) before you insert the image into the presentation. This is time-consuming, but may further reduce the size of the converted presentation files - potentially a desirable result. This issue is a concern only when the original image is large and the resized image is much smaller.