Panasonic Lumix DMC-FZ15By: Dave EtchellsPanasonic introduces a four-megapixel digicam with the high quality optics of a 12x Leica lens. <<FZ15 Sample Images :(Previous) | (Next): Print-Friendly Review Version>> FZ15 Imatest ResultsReview First Posted: 10/30/2004 |
Detailed analysis of the Panasonic FZ15 images, from Imatest(tm)
I've recently begun using Norman Koren's excellent "Imatest" analysis program for quantitative, thoroughly objective analysis of digicam test images. I highly commend it to our technically-oriented readers, as it's far and away the best, most comprehensive analysis program I've found to date. (And with an introductory price of only $59, it's hard to beat.)
My comments below are just brief observations of what I see in the Imatest results. A full discussion of all the data Imatest produces is really beyond the scope of this review: Visit the Imatest web site for a full discussion of what the program measures, how it performs its computations, and how to interpret its output.
Here's some of the results produced by Imatest for the Panasonic FZ15:
Color Accuracy
For the most part, the Panasonic FZ15 has pretty good hue accuracy, but like many consumer-level digicams, tends to oversaturate its colors somewhat. The oversaturation is shown by the extent to which the circles (camera color) are displaced outward (higher saturation) relative to the ideal values (squares). On average, color saturation of swatches on the MacBeth ColorChecker(tm) chart are 109.8% of their ideal values. (An average oversaturation of 9.8%.)
Color here is generally pretty good, with the slight ovesaturation that most
consumer cameras have. There are slight hue shifts in some colors, the blues
generally being pulled toward more purple tones, oranges being pulled toward
red, and reds pulled a bit toward purple. I think these color twists are some
of why the FZ15's skin tones tend to be on the pinkish side, I don't think
the overall effect is too severe.
Color Analysis
These images show the color behavior of the Panasonic FZ15 directly. In each color swatch, the outer perimeter shows the color as actually captured by the camera, the inner square shows the color after correcting for the luminance of the photographed chart (as determined by a 2nd-order curve fit to the values of the gray swatches), and the small rectangle inside the inner square shows what the color should actually be, based on perfect rendering to the sRGB color space.
For me, the bottom line on the chart above is that the hue shifts mentioned
earlier don't really have all that big an impact on the colors visually.
Gray Patch Tone and Noise Analysis
There's a lot in this particular graph, a lot more than I have room to go into
here. Bottom line, the Panasonic FZ15's noise levels are a little higher than
average across the board, but the noise spectrum is such that the noise is fairly
fine-grained.
This chart compares the Panasonic FZ15's noise performance over a range of
ISOs against that of other cameras. As you can see, the FZ15 is lower than average
at low ISO levels, but a little higher than average at higher ISOs. - The positive
side of its high-ISO behavior though, is that the camera tends to hold onto
detail in subject areas of subtle contrast better than some competing models
do.
The chart above shows consolidated results from spatial frequency response
measurements in both the horizontal and vertical axes. The "MTF 50"
numbers tend to correlate best with visual perceptions of sharpness, so those
are what I focus on here. The uncorrected resolution figures are 1169 line widths
per picture height in the horizontal direction (corresponding to the vertically-oriented
edge), and 1064 along the vertical axis (corresponding to the horizontally-oriented
edge), for a combined average of 1117 LW/PH. Correcting to a "standardized"
sharpening with a one-pixel radius increases this number a fair bit, to an average
of 1361 LW/PH. These are very good numbers for a 4-megapixel camera, more in
the range of what a lot of 5-megapixel models deliver.
For the real techno-geeks, the two plots below show the actual edge response
of the FZ15, for horizontal and vertical edges:
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