Panasonic DMC-L10 Imatest Results

Panasonic Lumix DMC-L10 Imatest Results

We routinely use Norman Koren's excellent "Imatest" analysis program for quantitative, thoroughly objective analysis of digicam test images. I highly recommend it to our technically-oriented readers, as it's far and away the best, most comprehensive analysis program I've found to date.

My comments below are just brief observations of what we 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 Lumix DMC-L10:

The Panasonic DMC-L10 showed excellent color accuracy, with only minor oversaturation of bright reds and some very slight oversaturation of greens and blues. The L10 actually undersaturates some yellows. Hue accuracy was also excellent, with most of the hue shift occurring in the cyans, sky blues, and oranges. Average saturation was 105.9% (oversaturated by 5.9%, mostly in the reds, a bit in some blues). Average "delta-E" color error was only 4.47 after correction for saturation, making the L10 one of the most hue-accurate cameras we've tested. All in all, a very good color response for an SLR.

Using the Adobe RGB color space (which provides a much wider gamut, or range of colors that can be expressed), the Panasonic DMC-L10 slightly more saturated blues and greens, but with larger shifts in hue accuracy, especially reds, oranges and yellows. Average saturation-corrected hue error was 7.42 "delta-E" units, with an average saturation of 109.4%. Looking back over Adobe RGB color error results for several other cameras, we found that there is indeed a lot of variation and inaccuracy in the Adobe RGB results from many DSLRs. If you mouse over the links below the illustration above, you can compare the L10's Adobe RGB response with that of two other cameras, the Canon EOS 40D and the Nikon D80.

This image shows how the Panasonic Lumix L10 actually rendered the colors of the MacBeth chart, compared to a numerically ideal treatment. In each color swatch, the outer perimeter shows the color as actually captured by the camera, the inner square shows the numerically ideal color, after correcting for the luminance of the photographed chart (as determined by a second-order curve fit to the values of the gray swatches), and the small rectangle inside the inner square shows the numerically ideal color, without any luminance correction. This image shows the excellent hue accuracy, as well as a contrast curve that results in moderate overexposure of some of the highest-saturation swatches.

There's a lot in this particular graph, a lot more than we have room to go into here. (This set of plots has also changed a little in the more recent versions of Imatest. Some of the plots that were shown here previously are now shown in other Imatest output. Since we largely focus on the Noise Spectrum plot, we'll only show the graphic above, which includes that plot.)

In comparing these graphs with those from competing cameras, I've found that the Noise Spectrum graph at lower right is the most important. Cameras that manage to shift their noise spectrum to higher frequencies have much finer-grained noise structures, making their noise less visually objectionable. In the graph above, this would show up as a noise spectrum curve that remained higher on the right side, representing higher noise frequencies. The champion at this was the Canon EOS-1Ds Mark II, which produced remarkably fine-grained image noise, even at very high ISOs. The L10 does avoid lumping the noise spectrum up around zero frequency too much, but still doesn't spread as much energy into the higher spatial frequencies. The result: It's noise at low ISOs has a more or less average "grain size".

Here's the same set of noise data at ISO 1,600. Here, the Noise Spectrum graph shows much lower high-frequency content, evidenced by the steeper slope of the noise curve, and the extent to which it's lumped up on the left side of the graph. Absolute noise levels are also slightly higher those of many competing cameras, and the shaping of the noise characteristic results in a rather coarse "grain" structure. Personal tastes invariably differ quite a bit, but we find the Panasonic L10's high-ISO noise characteristic to be somewhat under par compared to competing models. (Note though, that a good RAW converter and associated third-party noise reduction filtering software can deliver considerably better results than the camera's own processor does in making the in-camera JPEGs.)

This chart compares the Panasonic DMC-L10's noise performance over a range of ISOs against that of other cameras. While I continue to show noise plots of this sort because readers ask for them, I each time point out that the noise magnitude is only a small part of the story, the grain pattern being much more important. In the case of the Panasonic L10, the magnitude of the image noise is quite low at ISO 100, but increased to somewhat higher than average levels at ISOs 200 and especially 400. At ISO 800, more aggressive noise reduction has kept noise levels identical to ISO 400, but at ISO 1600, L10 noise levels return to just slightly above average for this peer group.

Panasonic L10 Dynamic Range Analysis

A key parameter in a digital camera is its Dynamic Range, the range of brightness that can be faithfully recorded. At the upper end of the tonal scale, dynamic range is dictated by the point at which the RGB data "saturates" at values of 255, 255, 255. At the lower end of the tonal scale, dynamic range is determined by the point at which there ceases to be any useful difference between adjacent tonal steps. Note the use of the qualifier "useful" in there: While it's tempting to evaluate dynamic range as the maximum number of tonal steps that can be discerned at all, that measure of dynamic range has very little relevance to real-world photography. What we care about as photographers is how much detail we can pull out of the shadows before image noise becomes too objectionable. This, of course, is a very subjective matter, and will vary with the application and even the subject matter in question. (Noise will be much more visible in subjects with large areas of flat tints and subtle shading than it would in subjects with strong, highly contrasting surface texture.)

What makes most sense then, is to specify useful dynamic range in terms of the point at which image noise reaches some agreed-upon threshold. To this end, Imatest computes a number of different dynamic range measurements, based on a variety of image noise thresholds. The noise thresholds are specified in terms of f-stops of equivalent luminance variation in the final image file, and dynamic range is computed for noise thresholds of 1.0 (low image quality), 0.5 (medium image quality), 0.25 (medium-high image quality) and 0.1 (high image quality). For most photographers and most applications, the noise thresholds of 0.5 and 0.25 f-stops are probably the most relevant to the production of acceptable-quality finished images, but many noise-sensitive shooters will insist on the 0.1 f-stop limit for their most critical work.

The image below shows the test results from Imatest for an in-camera JPEG file from the Panasonic L10 with a nominally-exposed density step target (Stouffer 4110), and the L10's contrast setting at its default position.

These are rather lackluster numbers for a modern DSLR, and they're unfortunately reinforced by our visual inspection of the L10's images: Dynamic range does indeed seem to be limited, as seen in the deliberate torture-test of our "Sunlit Portrait" shot. There, the L10 lost the strong highlights while simultaneously producing plugged, noisy shadows.

Processing the L10's RAW files through Adobe Camera Raw (ACR) version 4.2 improved dynamic range by about a third of an f-stop. ACR did shift slightly more of the noise energy into high spatial frequencies, making its residual noise a bit less objectionable than that found in the camera JPEGs.

Fiddling quite a bit with ACR's manual controls, I managed to eke out about another 2/10 stop of dynamic range at the highest quality threshold, but lost a similar amount at the lowest quality threshold. All in all, the L10's dynamic range is one of the weaker areas of its performance.

Dynamic Range, the bottom line:

The net result was that the L10 came in behind most other current DSLR models, its in-camera JPEGs bested all but the Olympus E410 and E510, among current models we've tested.

To get some perspective, here's a summary of the Panasonic DMC-L10's dynamic range performance, and how it compares to other digital SLRs that we also have Imatest dynamic range data for. (Results are arranged in order of decreasing dynamic range at the "High" quality level.):

The results shown in the table are interesting. One of the first things that struck me when I initially looked at test data for a wide range of d-SLRs, was that here again, purely analytical measurements don't necessarily correlate all that well with actual photographic experience. There's no question that the Fuji S3 Pro deserves its place atop the list, as its unique "SR" technology does indeed deliver a very obvious improvement in tonal range in the highlight portion of the tonal scale. I was surprised to see the analytical results place the Olympus EVOLT as highly as they did, given that our sense of that camera's images was that they were in fact noisier than those of many other d-SLRs that we looked at. In the other direction, I was quite surprised to see the Nikon D2x place as low on the listings as it did, given that we found that camera's shadow detail to be little short of amazing.

One thing that's going on here though, is that we tested each camera at its lowest ISO setting, which should produce best-case noise levels. This is in fact what many photographers will be most interested in, but it does perhaps place some of the Nikons (like the D40) at a disadvantage, as their lowest ISO setting is 200, as compared to the ISO 100 settings available on most other models.

Regardless of the positions of the other cameras though, the Panasonic L10 does appear to offer a fairly limited dynamic range. Faced with high-contrast subjects, it struggles to hold onto highlight detail, while simultaneously delivering plugged, noisy shadows.

As I always say though, at the end of the day I think you have to take the figures here with a grain of salt, and look at actual images with your own eyes to see what you make of each camera's tonal range and noise levels. We'll continue performing these dynamic range tests on the digital SLRs that we review, but (just as with the laboratory resolution target results), we suggest that you not rely on them exclusively for making your purchase decisions.

Panasonic DMC-L10 Resolution Chart Test Results

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 1,729 line widths per picture height in the horizontal direction (corresponding to the vertically-oriented edge), and 1,755 lines along the vertical axis (corresponding to the horizontally-oriented edge). Correcting to a "standardized" sharpening with a one-pixel radius increased both vertical and horizontal resolution significantly, resulting in an average of 2,026 LW/PH, a bit below the best we've seen for a 10-megapixel camera.

To see what's going on, refer to the plots below, which show the actual edge profiles for both horizontal and vertical edges, in both their original and corrected forms. Here, you can see that there is in fact a little in-camera sharpening applied (the noticeable bump at the top ends of the black curves), that the standard sharpening operator only corrects for somewhat. While we didn't run the graphs to prove it, you'd likely do well to run the L10 with slightly lower than normal in-camera sharpening and the use strong/tight sharpening post-exposure in Photoshop or some other image editor.