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Compared to... (contd.)

Colour Chart Comparison

Now we'll use the data in our review database to compare the QV-4000 colour and resolution to three other four megapixel digital cameras: the Canon PowerShot G2, Sony DSC-S85 and Olympus C-4040Z.

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.

Casio QV-4000 Canon PowerShot G2
Sony DSC-S85 Olympus C-4040Z

All of these four megapixel digital cameras are very close for colour balance. Casio have done a good job of producing well balanced yet vivid colours. Here are some general observations:

  • Better overall colour balance than the C-4040Z (stronger reds and yellows)
  • Less saturated than the DSC-S85 (good, plus you can adjust via record menu)
  • Blues not quite as strong as the Canon G2
  • Grayscale is a little contrasty, not much detail beyond patch 15

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 Casio
QV-4000
Canon
PowerShot G2
Sony
DSC-S85
Olympus
C-4040Z
Black 21,23,25 45,43,42 17,17,19 35,36,35
       
Middle Gray 91,92,94 107,106,110 76,81,79 111,105,110
       
White 198,199,199 208,210,208 188,189,189 211,210,217
       
Magenta 178,14,100 196,37,116 170,12,124 190,46,110
       
Red 178,4,33 195,30,35 176,0,40 178,44,45
       
Yellow 194,176,64 205,195,20 181,180,14 191,195,65
       
Green 28,129,59 43,152,68 24,131,27 41,145,84
       
Cyan 10,141,188 23,169,234 23,158,175 52,166,220
       
Blue 37,26,104 61,56,133 23,31,112 75,58,118
       


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.
Casio QV-4000
Canon PowerShot G2
Sony DSC-S85
Olympus C-4040Z

Measurable findings (three measurements taken for each camera):

Camera Measurement Absolute Res.  Extinction Res. 
Casio QV-4000 Horiz LPH 1150  *1350 
Vert LPH 1100  1400 
5o Diagonal LPH 1000  n/a 
Canon PowerShot G2 Horiz LPH 1250  *1450 
Vert LPH 1200  *1500 
5o Diagonal LPH 1000  n/a 
Sony DSC-S85 Horiz LPH 1250  *1650 
Vert LPH 1200  1650 
5o Diagonal LPH 1000  n/a 
Olympus C-4040Z Horiz LPH 1150  *1350 
Vert LPH 1100  1400 
5o 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)
5o Diagonal Lines set at 5o 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 Casio QV-4000 matched Olympus's C-4040Z for resolution, at the lower end of what we'd expect from a four megapixel digital camera. Taking a closer look at the QV-4000's resolution chart it's clear to see that at least some of the artifacts are a result of its noise reduction algorithm, the rest has been lost in unsophisticated Bayer interpolation.

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