Hewlett Packard PhotoSmart 812 Review
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.
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.
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.|
|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|
|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)|
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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