EM5 vs GH2 RAW Image Noise Comparison (ISO=200)

Started Apr 28, 2012 | Discussions thread
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EM5 vs GH2 RAW Image Noise Comparison (ISO=200)
Apr 28, 2012

Have had a look at RicksAstro 's recently posted EM5 and GH2 RAWs recorded at ISO=200 from:

http://www.ricksastro.com/temp/em5/EM5_16P4180038.ORF
http://www.ricksastro.com/temp/em5/16P1080017.RW2

From: http://forums.dpreview.com/forums/read.asp?forum=1041&message=41260897

Note: The correct download link for the GH2 RAW image-file was posted later in the same thread .

RawDigger reports that the ratio of the Average/Peak levels between the EM5 and the GH2 equals -0.574 EV (for the entire image-frames). As a result, the processed images were scaled by a difference of 0.574 EV so as to normalize for that difference in RAW-level scaling, and a 800x600 pixel uniform-field "patch" was derived from the lower-left corner of the GH2 and the EM5 images.

Rather interestingly, the White Balance parameters that each camera used are very different. The fluorescent lamp color-temperature in the test-shot scene was (likely) something in the range of 3,000 Degrees Kelvin. While the GH2 used a Color Temperature of 2835 Degrees K and a Tint of 0.943, the EM5 used a Color Temperature of 5051 Degrees K (a color-temperature nearly double that of the the flourescent lamp light-source), and a Tint of 0.532. The following analysis was conducted using the White Balance parameters (presumably) chosen by each camera's AWB system. Thus, it appears that the nature of the Bayer array RGB color-filters is significantly different .
.

Used RAW Therapee 4.082 for Win32-bit in the following configuration when processing:

Exposure tools :
Neutral
Exp. Comp. - For the EM5 used a value of +0.574 EV more than for GH2.
Highlight recovery amount=0
Black=0
Shadow recover=0
Brightness=0
Contrast=0
Saturation=0
Lab Brightness=0
Lab Contrast=0
Lab Saturation=0
Tone Curve=Linear
All other functions disabled.
.

Detail tools:
Contrast by detail levels disabled.
All other functions disabled.
.

Color tools:

White Balance = Camera Settings

Color Management:
Input profile=No profile
Working profile=sRGB
Output profile=sRGB
Outpt gamma=standard_g=2.2

All other controls in their default state.
.

Transform tools:
Crop = enabled
Width=800 pixels
Height=600 pixels
All other functions disabled.
.

Raw tools:
De-mosaicing algorithm=AMAZE
False color suppression steps=0
All other functions disabled.
.

16-bit sRGB color-space TIFF output image-files were exported from RAW Therapee 4.082 , and analyzed using PaintShop Pro X4 . XnView 1.986 was used to convert the 16-bit TIFs to loss-less (no Chroma Sub-sampling, no Quantization data-compression) 8-bit JPGs for display below.
.

Here is the GH2 (RAW scaling of +4.43 EV):

Here is the EM5 (RAW scaling of +5.00 EV):

Here is the difference (the absolute-value of the subtraction) of the GH2 and EM5 images:

The average (composite RGB) luminance of the GH2 and EM5 images differenced is the same (within plus or minus 0.42% measurement accuracy). The magnitude of the (vector-summed) difference between the two image-samples is a full -3.73 EV below their average luminance values
.

Guillermo Lujik 's excellent Histogrammar 1.2 (16-bit log EV X-axis mode) was used to analyze:

A 16-bit log histogram of the GH2 image above (RAW scaling of +4.43 EV):

A 16-bit log histogram of the EM5 image above (RAW scaling of +5.00 EV):

A 16-bit log histogram of the image of the difference of the GH2 and EM5 images (above):

.

Comment : I see a somewhat better looking Signal/Noise Ratio in the EM5 sample relative to the GH2 sample. Numerical analysis does not indicate that the magnitude of the difference in image-noise that is present in each sample is highly significant (-3.73 EV below average luminance).

DM ...

Panasonic Lumix DMC-GH2
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