Photos for TV and DV
- 17 February, 2003 08:25
As CD burners and home DVD players become common, more people are using these technologies to display photographs. Rather than sticking to a plain slideshow, some adventurous types are adding sound tracks and commentaries. This type of multimedia presentation is often created in a video editing package — unfortunately, your beautiful images can become mangled in the process. They may get distorted, the edges may disappear off your TV screen or the quality may drop. So what goes wrong and how can you make the most of the slideshow?
First you will need to decide on the size of a project. VCDs in PAL format require images to be exactly 352x288 pixels and, likewise, DVD images are 720x576. DVD dimensions will provide the best results with no apparent loss in screen quality. For the rest of the column, it will be assumed that the presentation is in DVD format. The process is the same for VCD, so simply adjust your dimensions accordingly.
Your first step is to gather your images together. Spend a little time on this process and don’t try to include every picture in your collection. Make any necessary colour adjustments and touch-ups, but don’t crop or resize the images at this stage.
For a DVD production, the final dimensions of your images must exactly match 720x576 pixels. Even the slightest variation will often result in a distortion or degradation of quality since the video program will need to resize the image when the slideshow is prepared. There are three techniques for getting the right dimensions without distorting an image:
- Adding Borders/adjusting canvas size
In practice, you will probably use all three. When compared to ‘print quality’ resolutions, the DVD dimensions of 720x576 pixels are relatively small and a VCD is even smaller (a simple 1-megapixel camera can take images at around 1200x800). You can use this difference to create on-screen panoramas (see the image examples one and two) or improve the framing of an image. Portrait images will have a significant border running down each side, so try cropping the image to better fit the landscape dimensions of the TV.
The easiest approach to get your dimensions right is to resize the proportionally-longest dimension and then increase the canvas size to get the correct second dimension. Confused? Try this example using an image at 1200x800 pixels. Resize it down to 720x480. Now vertically enlarge the canvas so that the difference between 480 and 576 is filled with a black background. The image will take on the ‘letterbox’ appearance of widescreen movies (if the image was a portrait of 800x1200, it would have been resized to 384x576 then the left and right edges filled out to 720x576).
To fill in the background of an image, use the canvas setting. Select Image-Canvas Size from the menu (this is for both Paint Shop Pro and Photoshop) and enter the new values: 720x576. Make sure that the options to centre the image vertically and horizontally are selected, or your border will be skewed to one side. Click OK and a new background should appear. Its colour will be determined by the background colour listed in the program’s colour picker (these are the two coloured squares on your tools menu).
The image on this page started at 2000x1320. To create the panoramic view, it was cropped to a very narrow 720x124. Increasing the vertical canvas from 124 to 576 completes the DVD dimensions. The final image does not look like much on paper but on a large TV screen the effect is considerably better. Not all images need to be cropped this heavily, but experimenting can produce some interesting results.
Safe zone and invisible edges
The primary difference between the viewing area on the PC and TV is that TVs have a large ‘safe zone’. This is a blocked-out area around the edge of the screen that cuts out approximately 10 per cent of the image in both width and height. When playing videos on a PC, you don’t experience this.
The simplest solution is to introduce a black border around your images to approximately match the safe zone (use the canvas technique described above). Your image will be slightly smaller, but at least it can be seen. Some images may not have a problem with the safe zone, but there is nothing worse than a group photograph where the people on the edges are not visible.