Resolution Chart Comparison (JPEG and Raw)
Images on this page are of our standard resolution chart which provides for measurement of resolution up to 4000 LPH (Lines Per Picture Height). A value of 20 equates to 2000 lines per picture height. For each camera we use the relevant prime lens (the same one we use for all the other tests in a particular review). The chart is shot at a full range of apertures and the sharpest image selected. Studio light, cameras set to aperture priority (optimum aperture selected), image parameters default. Exposure compensation set to deliver approximately 80% luminance in the white areas.
What we want to show here is how well the camera is able to resolve the detail in our standard test chart compared to the theoretical maximum resolution of the sensor, which for the charts we shoot is easy to work out - it's simply the number of vertical pixels (the chart shows the number of single lines per picture height, the theoretical limit is 1 line per pixel). Beyond this limit (which when talking about line pairs is usually referred to as the Nyquist frequency) the sensor cannot faithfully record image detail and aliasing occurs.
This limit is rarely attained, because the majority of sensors are fitted with anti-aliasing filters. Anti-aliasing filters are designed to reduce unpleasant moiré effects, but in doing so, they also reduce resolution (the relative strength and quality of these filters varies from camera to camera). In theory though, a sensor without an AA filter, when coupled with a 'perfect' lens, will deliver resolution equal to its Nyquist limit. Therefore, even though it may be effectively unattainable with normal equipment in normal shooting situations, an understanding of a sensor's theoretical limit provides a useful benchmark for best possible performance. Nyquist is indicated in these crops with a red line.
On this page we're looking at both JPEG and Raw resolution. For a (more) level playing field we convert the latter using Adobe Camera Raw. Because Adobe Camera Raw applies different levels of sharpening to different cameras (this confirmed) we use the following workflow for these conversions:
- Load Raw file into Adobe Camera Raw (Auto mode disabled)
- Set Sharpness to 0 (all other settings default)
- Open file to Photoshop
- Apply a Unsharp mask tuned to the camera, usually 100%, Radius 0.6, Threshold 0
- Make 100% crops and save the original file at JPEG quality 11 for download
It is our standard practice to evaluate shots of our resolution chart only at a camera's full resolution setting. Due to the unique design of the X10's EXR sensor, however, we're also providing access to the 6MP resolution images in both Raw and JPEG mode. Click on the thumbnails below to compare results among all four files at original size.
|12MP JPEG (4000 x 3000) 4.5MB||12MP Raw (4000 x 3000) 18.9MB|
|6MP JPEG (2816 x 2112) 2.7MB||6MP Raw (2816 x 2112) 17.1MB|
Vertical resolution (12MP capture)
|Raw (Adobe Camera Raw 7.1)|
Horizontal resolution (12MP capture)
|JPEG||Raw (Adobe Camera Raw 7.1)|
You can see that the JPEG files fall well short of the sensor's theoretical Nyquist value. We would struggle to identify distinct line separation much beyond 20 LPH, an acceptable if mediocre result. The far more important observation here, however, is how soft the ACR-processed Raw file is in comparison. Results like this indicate that the unique nature of the EXR sensor poses significant challenges for third party raw conversion software in the demosaicing process.
We've not seen significantly better results from other raw converters, including the SilkyPix-branded version included with the X10. At this point and time, Fujifilm's internal raw-conversion simply provides a noticeably more successful result (as well as being much less of a hassle to use).