Sidebar 2: Improving player picture quality

For most applications, the player's own image-processing software will produce satisfactory picture quality. Some of the processing is handled automatically by the downloading software on the host computer, but most of the work is done by the player itself. If you are not happy with the results, there is a lot you can do to improve the picture quality for both the internal screen and the TV-out.

Use an image- or video-editing program to prepare the images
For still photos and slides, it's best to edit and process the images in an editing program such as Adobe Photoshop Elements. You will have more control and get better results than using the player's automatic image-processing software. Prepare the images in a form that the player won't need to modify so that they are downloaded and displayed by the player exactly as you've prepared them. Every extra processing step (rescaling the image size or transcoding the image file format) will degrade the picture quality. The same is true for videos. For prerecorded videos, your choices are generally limited, and for copy-protected videos, you likely won't have any choices, other than possibly the bit rate.

Use low-compression JPEGs
The player software generally uses a relatively high degree of compression for most JPEG images in order to reduce the storage requirements for the file. This introduces compression artifacts into the images. The greater the compression, the more likely you are to notice the artifacts onscreen. For best results, use an image-editing program and save the image with the JPEG option set for maximum or highest quality.

Use low-compression video
If you are recording the video yourself, use the highest bit rate that you can. If you are downloading a prerecorded video, select the highest bit rate available. But note that there is a limit on how high any player can go. If the bit rate or the resolution format is too high for the player hardware to keep up with, the frame rate, the smooth motion, and audio sync will degrade. There are so many video formats and variables for both the recorder encoding and the player decoding that it is impossible to provide specific recommendations. You will simply have to experiment and compare the results for your particular player. In general, WMV (Windows Media Video) and MPEG-4-AVC (Advanced Video Coding, also known as H.264) will provide the best picture quality for a given bit rate. All of the players except the Apple iPod support WMV; however, the Apple iPod is the only player that supports MPEG-4-AVC. All the other players support only MPEG-4-SP (Simple Profile).

Use a lossless file format
Low-compression JPEGs generally perform quite well on all but the most complex images. Under those circumstances, it is best to switch to one of the perfect lossless file formats, such as BMP, GIF, PNG, or TIFF. Make sure that the player itself supports one of these file formats rather than simply transcoding them on the host computer, most often to highly compressed JPEG. Note that while there is a Lossless JPEG format, none of these players support it. GIF and PNG support only 256 screen colors, so they work well for graphics images used in presentations, but not for photos. TIFF files come in a very large number of formats, so you will need to test for compatibility. BMP is the best all-around lossless format, but it takes the most space. It is so easy to implement, I am amazed that only two of the six players support it. However, if you scale the images to the native resolution of the player's screen, the BMP file size won't be very large.

Scale to the native resolution of the display
For the best picture quality and fastest processing speed, the pixel size of the image should match the native resolution of the player's display screen. If it doesn't, it has to be corrected by the player in a process called image rescaling. It isn't crucial for most photographs because the images are relatively smooth, but when there is fine detail in an image, the processing is critical for maintaining sharpness and avoiding ugly artifacts. The Apple iPod was by far the best performer and delivered outstanding image rescaling. All of the other players had significant rescaling artifacts. Sometimes the rescaling can be done with bundled player software on the host computer. For best results, use an image-editing program to rescale the images to the native resolution of the player's display screen. If you are also going to display the image on a TV, then make a second copy for the native resolution of the TV (see below). Note that host computer software may sometimes automatically rescale imported images to the 640x480 TV-out resolution, which is not optimal for the player's own display screen (except for the Creative Zen Vision, which has a 640x480 screen). If that isn't satisfactory, scale the images yourself as described above. This is especially important if you're not planning to use TV-out. For video, you should pick a format, resolution, and bit rate that provide the fewest artifacts as discussed above.

Match the aspect ratio of the screen
In order to make full use of the relatively small player screen, you should try to have the images match the aspect ratio of the screen. Otherwise, you'll see black bars at the top and bottom or the left and right of the screen. Use an image editor to crop the pictures. If you are using TV-out with a TV that has an aspect ratio different from the player's screen, then you should crop the images for the TV aspect ratio as well (see TV out, below).

Adjust the image black level, contrast, and color saturation
If the bright portions of images seem washed out (called white or bright compression), then lower the contrast so that the peak intensities no longer reach the compressed portion of the grayscale. If the dark portions of images seem washed out, then lower the black level a bit, typically with the (inappropriately named) brightness control. If the colors appear washed out, then intensify them with a color saturation control. These adjustments generally need to be made in an editing program since few players implement these controls.

Use the DisplayMate image optimizer
The DisplayMate image optimizer mathematically processes any photo or image for a particular display to accurately correct for errors in the display's internal grayscale, then produces a corrected and optimized image with the best and most accurate picture quality that the display can deliver (with an optimum grayscale and enhanced color).

Improving TV-out
The native resolution for TV-out is generally 640x480 with a standard 4:3 aspect ratio, but some players also have an anamorphic 16:9 wide-screen option. For best results, you should scale source images to the TV-out resolution and aspect ratio. Because TV-out has a much higher resolution than the screens on most players and the images appear on a much larger screen, image defects often become more obvious. Thus, all the issues mentioned here are much more important with TV-out. For videos, you should pick the highest resolution and bit rate possible and try to match the aspect ratio of the screen, as discussed above.

In addition to personal photos and videos, these players can be used for all sorts of TV-out presentations. If there are images with text, graphics, or fine detail, as in a business presentation, rescaling artifacts and NTSC (cross-color) artifacts can have a significant impact on picture quality. The Apple iPod is by far the best performer in this case, even for composite video. The iPod is also the only unit in this roundup that offers an S-Video output (with the optional docking station). S-Video generally produces a higher-quality TV signal than the composite-video output available from the other players, although good video processing within the TV can neutralize this performance difference.

Avoid multiple processing steps
All compressed images (JPEG and video) degrade somewhat every time they are transcoded, processed, or saved to a file, so it's best to minimize the number of processing steps that you perform. Always use the highest quality (lowest compression) for all intermediate processing steps. If you're going to significantly compress the images, do it only for the final output step. For videos, avoid transcoding from one format to another.

Automate the file processing
Some image-editing programs can automatically process all of the files in one or more folders with a single command. Use it to resize and convert files to JPEG in one operation. Set the destination to the staging folder you use for downloading files to the player.

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