Pentax Optio V20

Overall the V20 produced mediocre but not unacceptable test results, with low light and video performance scoring particularly well, and noteworthy shortcomings in white balance and resolution.

Color (8.05)
Often what you see is not what you get, when it comes to your digital camera. You see a pale blue sky on the LCD when you pres the shutter, yet somehow when you review the photo the sky is a darker, richer hue. The delicate yellow flower you found growing by the roadside looks strangely orange in your photo. Sometimes the effect is intentional on the part of a camera manufacturer who thinks warmer, richer colors will look more appealing. Sometimes it's simply a camera that's not doing its job properly. Either way, we prefer accuracy in our color reproduction, so we take our test cameras into the lab, shoot an industry-standard GretagMacbeth color chart under carefully controlled lighting conditions, analyze the resulting images using Imatest software and figure out precisely how precisely the camera is delivering the colors we experienced with our naked eyes.

In the Imatest output chart below, which recreates the 24 color squares from the GretagMacbeth chart, the color as captured by the camera is shown in each outer rectangle, the chart color corrected to match the luminance of the camera image is shown in the inside square, and the original chart  color is shown in the inset rectangle.

 

The same underlying data is represented more diagrammatically in the chart below. Here, the original chart color is shown in the square, the color as captured by the camera is shown in the circle, and the difference between them is represented by the length and direction of the connecting line. As you can see, the reproduction of skin tones (approximated by the first and second squares on the chart) is reasonably accurate, but blue shades are significantly shifted off-hue, as is the yellow. Overall saturation is quite accurate at 101.8% of the ideal.

The long lines for the blue shades indicate significant color shift.

Resolution (5.87)
The key lesson to learn about camera resolution is that it is not measured in megapixels. The megapixel figure describes how many photo-receptive dots are available on the image sensor. But the actual sharpness of your photos is governed by many additional factors, including the quality of the camera lens and the processing routines applied to the digital information captured by the sensor. To tease out the true picture of a camera's resolution, we shoot an array of photos of an industry-standard resolution chart under tightly controlled lighting conditions, at a range of distances and exposures, and analyze those images using Imatest to determine image sharpness measured in line widths per pixel height (lw/ph).

Close-up of a V20 shot of our resolution chart

In the best-case combination of lighting conditions and zoom lens setting, the V20 managed only 1553 lw/ph horizontally, with inconsequential software oversharpening. This compares poorly with the competition overall. The Canon SD1100 IS, for example, managed 1783 lw/ph, while the Casio stands out with a test result at 2774 lw/ph.

White Balance (6.49)
A digital camera needs to adjust not only to the intensity of illumination in a photo, by coming up with an appropriate exposure setting, but also to the color of the light, which requires white balance adjustment. Our brains do a pretty good job of adjusting for the color of the light around us: a white page pretty much strikes us as being white, whether it's illuminated by a yellowish household bulb or a greenish fluorescent. Making that adjustment using processors and software is much more difficult, though, than making it using brain tissue, though, and like many an inexpensive point-and-shoot before it, the V20 proved quite good t handling some light sources and miserable dealing with others.

We test two different types of white balance performance. The first relies on the camera's circuitry to automatically identify the appropriate adjustment. The second uses the camera's built-in white balance presets. provided to allow the photographer to manually set the camera for the current lighting situation.

Auto White Balance (6.39)
The automatic white balance system did an excellent job delivering accurate color when shooting with the built-in flash, and also handled fluorescent lighting very well. The same cannot be said for shooting under tungsten lighting, as found in standard (i.e., non-fluorescent) household bulbs, or in shaded sunlight, where recorded colors are off drastically. Note that the color shifts shown in the Imatest charts below are exaggerated to make the trends easier to see; you won't find color differences this drastic in your actual photos.

Preset (6.59)
It requires a bit more effort to manually select a white balance preset versus letting the camera do all the thinking, but when it comes to shooting under tungsten with the V20, that extra moment's preparation is well worth taking: color reproduction jumped from fairly awful to quite good when we shot using the tungsten preset. Using the preset for fluorescent illumination didn't make much difference, and for shade, the most flagrantly problematic area of our white balance test, it actually made an already bad situation slightly worse. No flash preset is provided, but considering how well the camera performed using flash in auto mode, none is really needed.
 

Exaggerated White Balance Errors (Presets)

Fluorescent Preset WB - Fluorescent Illumination

Cloudy Daylight preset WB - Daylight illumination

Tungsten preset WB - Tungsten illumination

As the comparative chart below makes clear, white balance is a problematic area for inexpensive point-and-shoots, and the V20 is no exception.  And it's worth noting that, while the Samsung apparently towers over the competition here, a bit  or grade inflation took place in our scoring procedure, since near-perfect scores under flash and fluorescent illumination compensated for average performance in other areas.