Olympus SP-570 UZ

Color (6.38)
When taking pictures, what you see frequently isn't what you get, especially when it comes to color reproduction. Whether caused by an intentional effort on the manufacturer's part to provide a more pleasing result, or simply the camera's innate inability to get it right, we always find noticeable differences between the reality and the reproduction. To figure out which colors are changing and by how much, we shoot an industry-standard GretagMacbeth color chart under bright, carefully controlled lighting and study the resulting images using Imatest image analysis software.
 

The Imatest chart shown below provides one window into the results for the Olympus SP-570UZ. The squares represent the color blocks from the GretagMacbeth chart. In each one, the outer ring shows the color captured by the camera, the inner square shows the chart color adjusted to match the luminance of the photo, and the smaller rectangle shows the uncorrected chart color.
 

Another useful Imatest color result chart reveals the degree of color shift. Here the original chart color is shown in the squares, the color as captured by the camera in the circles, and the difference between the two values shown by the length of the line that connects them.

The saturation is off for oranges and yellows, but the
basic color hues are close to the originals

Resolution (11.80)
The number of megapixels in a camera's spec sheet doesn't equal the actual resolution of the final image, which relies on a combination of image sensor, optics and image processing performance. To test the bottom-line sharpness of a camera, we shoot our resolution chart under bright studio lighting, at all available full-resolution ISO settings, and use Imatest to determine how many line widths per pixel height (lw/ph) the camera is able to resolve. This reveals the point at which the cleanly drawn lines from the printed chart turn into a gray blob in the photo. For the 570UZ, the best result was achieved at a sweet spot about halfway through the lens' zoom range, with the aperture at f/4.3. As you'd expect, this high level of resolution doesn't hold up for the full range of the zoom, with much softer results at both the wide angle and telephoto extremes.

A full-size section of our resolution chart as shot by the 570UZ

The strong performance in the middle zoom range earns the 570UZ an outstanding score compared to the other tested cameras.
 

White Balance (6.04)
When we look at a white object we're inclined to see it as white, no matter what kind of lighting it's under, because our brains automatically adjust to the different colored illumination. This task is a lot tougher for a computer's digital smarts than for our flesh-and-blood processors, and the camera's relative success in dealing with producing whiter whites under difficult conditions has a tremendous effect on the color reproduction in your final photos.
 

We test white balance performance in two ways. First we shoot our GretagMacbeth color chart using the camera's automatic white balance system, under a variety of light sources, and analyze the camera performance using Imatest. Then we use the camera's manual white balance presets, designed to allow the photographer to choose the type of illumination in effect rather than leaving the decision to the camera.

Auto White Balance (4,75)
As is usually the case in this test, the 570UZ did quite well with some types of illumination and poorly under other light sources. White balance using flash was good, and the camera's ability to automatically cope with fluorescent light was impressive, since this is an area that often causes problems. On the other hand, results for tungsten illumination (like standard household bulbs) and in shaded daylight were quite poor. The images below are generated by Imatest to indicate the type of color shift produced under each type of illumination. Note that these differences are exaggerated substantially for illustration purposes; you wouldn't see this level of color shift in your actual photos.
 

Preset (7.33)
The camera's strength under fluorescent light we saw in the automatic white balance test was even more pronounced here. Olympus provides three different fluorescent presets, since fluorescent bulbs come in several different shades. We tried all three, and discovered the best-case setting produced exceptionally accurate results. Choosing the tungsten preset also produced a substantial performance boost, improving over a bad automatic result to the point where the color reproduction was quite good. Shade remained a sore spot, though. In fact, switching to the manual preset actually produced an even worse score than the automatic setting. There is no flash preset, hence the lack of a result here.

 

Compared to the other cameras in the ultra-zoom class, the 570UZ produced acceptable if unexciting results in our white balance testing.