Sony DSC-P9 Review: 12. Compared to...: Digital Photography Review

Compared to... (contd.)

Now we'll use the data in our review database to compare the P9's colour and resolution to three other four megapixel digital cameras: the Canon PowerShot S40, Olympus C-40Z and Sony DSC-S85.

Colour Chart Comparison

Colour charts are shot in daylight, Auto White Balance, EV compensation +0.3 (all cameras), measured light ~10 EV. This test is also dependent on the accuracy of the camera's auto white balance, the colour charts are shot in daylight but some camera's white balance is better than others. All cameras are given 20 seconds to "settle" before the shot is taken.

Sony DSC-P9 Canon PowerShot S40

Olympus C-40Z Sony DSC-S85

Virtually identical balance to the DSC-S85 except for the almost purple appearance of blues (this was a surprise as I hadn't observed this in real life shots). Otherwise a measured and neutral colour balance which succeeds because it provides vivid colour without looking false or overly saturated.

In the table below we're only measuring colour. The RGB values were measured from a VGA reduced image (to average colours, remove noise and eliminate JPEG artifacts) using the Eyedropper tool in Photoshop with a 5 by 5 Average Sample Size.

Patch	Sony DSC-P9	Canon PowerShot S40	Olympus C-40Z	Sony DSC-S85
Black	26,24,26	30,30,30	30,31,29	17,17,19
Middle Gray	96,94,98	103,102,103	100,99,99	76,81,79
White	192,190,192	215,210,211	214,216,211	188,189,189
Magenta	186,24,109	199,41,113	208,51,116	170,12,124
Red	174,17,29	196,33,42	196,45,41	176,0,40
Yellow	189,181,28	211,192,38	206,207,50	181,180,14
Green	37,137,66	33,140,67	8,143,63	24,131,27
Cyan	47,157,191	26,160,223	17,155,224	23,158,175
Blue	67,41,109	33,44,116	49,48,111	23,31,112

Again, it's fairly easy to see the 'red bleed' into the dark blue patch, this has had the effect of turning this patch purple (this appears to be a daylight auto white balance issue).

Resolution Chart Comparison

Shots here are of the PIMA/ISO 12233 standard resolution test chart (more of which are available in our comparison database). This resolution chart allows us to measure the actual performance of the lens and sensor system. It measures the ability of the camera to resolve lines at gradually higher resolutions and enables us to provide a definitive value for comparison purposes. Values on the chart are 1/100^th lines per picture height. So a value of 8 equates to 800 lines per picture height.

Studio light, cameras set to auto, all settings factory default. Exposure compensation +0.7 EV for all cameras.

Horizontal resolution Vertical resolution 5 degree diagonal res.

Sony DSC-P9

Canon PowerShot S40

Olympus C-40Z

Sony DSC-S85

Measurable findings (three measurements taken for each camera):

Camera	Measurement	Absolute Res.	Extinction Res.
Sony DSC-P9	Horiz LPH	1100	1400
	Vert LPH	1100	1400
	5° Diagonal LPH	1000	n/a
Canon PowerShot S40	Horiz LPH	1250	*1400
	Vert LPH	1100	1400
	5° Diagonal LPH	1000	n/a
Olympus C-40Z (D-40Z)	Horiz LPH	*1200	*1350
	Vert LPH	1100	1400
	5° Diagonal LPH	1000	n/a
Sony DSC-S85	Horiz LPH	1250	*1650
	Vert LPH	1200	1650
	5° Diagonal LPH	1000	n/a

* Some artifacts / moiré visible

Definition of terms:

LPH	Lines per Picture Height (to allow for different aspect ratios the measurement is the same for horizontal and vertical)
5° Diagonal	Lines set at 5° diagonal
Absolute Resolution	Still defined detail (below Nyquist frequency*)
Extinction Resolution	Detail beyond camera's definition (becomes a solid gray alias)
n/a	Not Available (above the capability of the test chart)
n/v	Not Visible (not visible on test results)

* Nyquist frequency defined as the highest spatial frequency where the CCD can still faithfully record
image detail. Beyond the Nyquist frequency aliasing occurs.

The DSC-P9 performed pretty much as we'd expected, based on what we've seen from its sample images and in comparison to the S40. Horizontal resolution is around (but just slightly less) than some of the other competition, vertical resolution is identical to the S40 and C-40Z (D-40Z). The DSC-S85 was included for comparison, as you can see it still manages to hold onto its crown for the highest resolution four megapixel consumer digital camera.

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