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Compared to...

Colour Chart Comparison

Using the test charts in our review database we can compare the HP 812 to three other digital cameras: Pentax Optio 430 (~$650), Canon PowerShot S40 (~$600) and the Minolta DiMAGE S404 (~$500).

Colour charts are shot in daylight, Auto White Balance, EV compensation +0.3 (all cameras except the 812 which doesn't provide manual exposure compensation), 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.

HP 812 Pentax Optio 430
Canon PowerShot S40 Minolta DiMAGE S404

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 HP
812
Pentax
Optio 430
Canon
PowerShot S40

Minolta
DiMAGE S404

Black 13,16,17 13,16,17 30,30,30 15,19,22
Middle Gray 81,88,92 83,89,94 103,102,103 70,72,87
White 228,237,234 190,192,194 215,210,211 192,191,201
Magenta 236,18,97 172,18,96 199,41,113 179,26,106
Red 239,10,31 173,7,29 196,33,42 176,29,44
Yellow 253,221,37 198,179,56 211,192,38 189,190,34
Green 0,130,68 28,122,74 33,140,67 3,113,45
Cyan 0,150,217 17,145,188 26,160,223 8,123,194
Blue 23,30,97 31,35,99 33,44,116 31,21,94

As noted on the previous page of this review while the 812 doesn't have exposure compensation it does automatically adjust the contrast and brightness of the image to provide the maximum use of the image greyscale (white to black), on this kind of shot it means that white is very nearly white and black is pinned down without being washed out. Colours are also very vivid, although I'd be concerned that the yellow and red patches are getting very close to overexposure.

Resolution 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.
HP 812
Pentax Optio 430
Canon PowerShot S40
Minolta DiMAGE S404

Measurable findings (three measurements taken for each camera):

Camera Measurement Absolute Res.  Extinction Res. 
HP 812 Horiz LPH 1000  * 1250 
Vert LPH 950  * 1200 
5° Diagonal LPH 800  n/a 
Pentax Optio 430 Horiz LPH 1100  * 1250 
Vert LPH 950  * 1250 
5° Diagonal LPH 900  n/a 
Canon PowerShot S40 Horiz LPH 1250  * 1400 
Vert LPH 1100  1400 
5° Diagonal LPH 1000  n/a 
Minolta DiMAGE S404 Horiz LPH * 1150  * 1350 
Vert LPH * 1100  * 1350 
5° Diagonal LPH 800  n/a 

* Moiré is 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.

While the new firmware does appear to make images sharper it hasn't been able to eek out any more resolution, this is probably limited by the lens. This is not the resolution we would expect from a four megapixel digital camera, nor the overall image 'look' and sharpness.

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