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JPEG Noise levels

ISO equivalence on a digital camera is the ability to increase the sensitivity of the sensor. This works by turning up the "volume" (gain) on the sensor's signal amplifiers (remember the sensor is an analogue device). By amplifying the signal you also amplify the noise which becomes more visible at higher ISO's. Many modern cameras also employ noise reduction and / or sharpness reduction at higher sensitivities.

To measure noise levels we take a sequence of images of a GretagMacBeth ColorChecker chart (controlled artificial daylight lighting). The exposure is matched to the ISO (i.e. ISO 200, 1/200 sec for consistency of exposure between cameras). The image sequence is run through our own proprietary noise measurement tool (version 1.6 in this review). Click here for more information. Room temperature is approximately 22°C (~72°F), simulated daylight lighting.

Panasonic G2 vs. Sony NEX 3 vs. Olympus E-P1 vs. Canon EOS 550D

  • Panasonic G2: Olympus 50 mm F2 Macro lens (@F6.3), Manual Exposure,
    JPEG Large/Fine, Manual WB, Default Parameters (Standard), Self-Timer
     
  • Sony NEX-3: Sony 50 mm F1.4 lens (via adapter), Manual Exposure,
    JPEG Fine, Manual WB, Default Parameters (Standard), Self-Timer
     
  • Olympus E-P1: Olympus 50 mm F2 Macro lens (@F6.3), Aperture Priority,
    JPEG Large/SHQ, Manual WB, Default Parameters (Standard), Self-Timer
     
  • Canon EOS 550D: Canon 50 mm F1.4 USM lens, Manual Exposure, Manual WB,
    Default Parameters, High ISO NR (Normal), JPEG Large / Fine
  Panasonic G2 Sony NEX-3 Olympus E-P1 Canon EOS 550D
ISO 100    
ISO 200
ISO 400
ISO 800
ISO 1600
ISO 3200
ISO 6400  
ISO 12800    

At lower ISO settings (100-400) the difference between all these cameras, in real terms, is minimal - the G2 has excellent detail but also shows a hint more noise than the two APS-C cameras here. This is the compromise demanded by the smaller sensor, and as you move up the ISO scale it's obvious that the Micro Four Thirds cameras are having to work harder to keep noise under control. To be fair they're doing a pretty good job of it, and until you get to ISO 3200 the G2 keeps up with the larger-sensored NEX and EOS cameras well enough (if we're talking about normal viewing magnifications - at 100% there is visibly more noise).

The new ISO 6400 option is - clever new Venus Engine or not - a 'step too far', and if you regularly shoot at anything approaching this kind of level you'd be better off with something sporting a larger sensor.

Finally it's worth noting that Olympus and Panasonic are taking a slightly different approach to (the default) noise reduction used, with Olympus going for a stronger NR producing cleaner, but less detailed output.

RAW noise (ACR 6.1, Noise reduction set to zero)

Here we look at the RAW files processed through Adobe Camera Raw (in this case version 6.1). Images are brightness matched and processed with all noise reduction options set to zero. Adobe does a degree of noise reduction even when the user-controlled NR is turned off.

The amount of NR applied 'under the hood' is not high, but it does vary by camera (Adobe is attempting to normalise output across different sensors), so we are still looking at a balance of noise and noise reduction, rather than pure noise levels. However, the use of the most popular third-party RAW converter is intended to give a photographically relevant result, rather than simply comparing sensor performance in an abstract manner.

  Panasonic G2 Sony NEX-3 Olympus E-P1 Canon EOS 550D
ISO 100    
ISO 200
ISO 400
ISO 800
ISO 1600
ISO 3200
ISO 6400  
ISO 12800    

The raw output shows that if you're mostly working in the lower registers of the ISO range it makes precious little difference which camera you choose - they all show a little noise at ISO 400, but nothing to worry about (remember these samples have noise reduction turned off). Above that the differences start to show, with the APS-C sensored Sony NEX and Canon EOS having at least a one (probably nearer a two) stop advantage over the G2.

High ISO noise - GF1 vs G2

One thing we noticed when playing with the G2's high ISO files was that the default JPEG rendering looked a little different to the last generation. As this quick comparison shows, the new engine does indeed treat noise in a different way. As you can see, there's visibly less luminance noise at ISO 800 and above (here compared to the GF1 with the latest firmware). It's not all good news though; we saw evidence of the color bleeding (caused by excessive chroma noise reduction) that plagued early Lumix cameras, and there's a slight loss of contrast and texture, implying that luminance NR has been turned up a little too. You can of course turn the NR down for JPEGs (or just shoot raw and do your own), but it's worth a mention here.

  ISO 800 ISO 1600 ISO 3200 ISO 6400
GF1  
G2

Raw vs in- camera JPEG noise reduction low contrast detail comparison

The G2 has five levels of noise reduction from -2 to +2. The crops below shows the effect of the highest, lowest and default settings from ISO 800 upwards when compared to Adobe Camera Raw (6.1) with noise reduction set to the minimum. At anything over ISO 800 there's quite a lot of noise to deal with. Our feeling is that the default is a little too high (we'd prefer to turn down the NR and live with a bit of grain rather than lose all detail to luminance blurring).

  ACR RAW NR OFF JPEG NR−2 JPEG NR0 JPEG NR+2
ISO 800
ISO 1600
ISO 3200
ISO 6400

Noise reduction and fine detail

The biggest issue with noise reduction - especially luminance noise reduction - is that in the process of blurring away the noise it can also have a very destructive effect on the detail in an image, particularly the fine, low contrast detail you might find in hair, fur or grass. To better judge the effect on fine detail lost due to noise reduction we have shot our new studio scene and produced crops from the feathers in the image. We have left out the 'Low' noise reduction setting as it only appears to apply chroma noise reduction which tends to have little impact on detail (fine contrast).

To check the effect of noise and noise reduction on low contrast detail we shoot our new studio setup at various ISO and noise reduction settings, then crop an area that's challenging to any camera. The very fine detail in the feathers will help to better judge the effect of noise reduction on fine detail.

Raw vs in- camera JPEG noise reduction low contrast detail comparison

As the crops below show, there's a lot of noise to deal with at higher ISO settings, and as you move to the top of the scale the blurring effect of noise reduction on fine detail is pretty extreme. As with previous Lumix models we'd prefer a wider range of NR options, and with the G2 specifically we feel that the default is a little too high. Ultimately this isn't a camera that performs very well over ISO 800 unless you stick to modest viewing magnifications.

  ACR (NR 0) JPEG NR−2 JPEG NR STD JPEG NR+2
ISO 800
ISO 1600
ISO 3200
ISO 6400
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