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Compared to... (contd.)

Now we'll use the data in our review database to compare the S45's color and resolution to three other four megapixel digital cameras: the Minolta DiMAGE F100, Sony DSC-P9, and Olympus C-40Z.

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.

Canon PowerShot S45 Minolta DiMAGE F100
Sony DSC-P9 Olympus C-40Z

A good balanced response, notably good blue, green and yellow compared to some of the other cameras here. Color is vivid without being over-saturated, and you can always control this with the camera's Effect menu.

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 Canon PowerShot S45 Minolta DiMAGE F100

Sony
DSC-P9

Olympus
C-40Z
Black 30,31,30 23,23,23 26,24,26 30,31,29
Middle Gray 100,101,100 95,96,97 96,94,98 100,99,99
White 207,208,204 202,209,207 192,190,192 214,216,211
Magenta 210,43,113 194,32,108 186,24,109 208,51,116
Red 205,34,47 172,21,33 174,17,29 196,45,41
Yellow 204,194,28 186,190,42 189,181,28 206,207,50
Green 16,137,79 5,146,69 37,137,66 8,143,63
Cyan 0,145,212 20,178,210 47,157,191 17,155,224
Blue 35,48,111 50,51,115 67,41,109 49,48,111

As noted in my F100 review color response from these four cameras is remarkably similar, most of the manufacturers seem to be getting closer to an optimum appearance for color from compact digital cameras. It's worth noting that the S45 manages to produce blues and yellows more accurately with less channel crossover than the others.


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 1/100th 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.
Canon PowerShot S45
Minolta DiMAGE F100
Sony DSC-P9
Olympus C-40Z

Measurable findings (three measurements taken for each camera):

Camera Measurement Absolute Res.  Extinction Res. 
Canon PowerShot S45 Horiz LPH 1250  1450 
Vert LPH 1150  1400 
5° Diagonal LPH 1000  n/a 
Minolta DiMAGE F100 Horiz LPH 1150  *1350 
Vert LPH 1150  1300 
5° Diagonal LPH 1000  n/a 
Sony DSC-P9 Horiz LPH 1100  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 

* 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 S45 managed to deliver a remarkable amount of resolution considering its compact lens system. Better still it does so without any noticeable moiré or strong sharpening artifacts. A very good performance for this class of cameras. The only thing worth noting may be the slight stepping visible in the 5° resolution lines.

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