Colour Chart Comparison
Using the test charts in our review database we can compare the Kodak DX4900 (~$400) to three other four megapixel digital cameras: HP 812 (~$500), 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 DX4900 which was set to +0.5 EV), 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.
|Kodak DX4900||HP 812|
|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.
Overall colour response was good with the DX4900 exhibiting good primary colours and a fairly good white balance (grey purity). Colours are noticeably more neutral than the 'fizzy' HP 812.
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 S40|
|Minolta DiMAGE S404|
Measurable findings (three measurements taken for each camera):
|Camera||Measurement||Absolute Res.||Extinction Res.|
|Kodak DX4900||Horiz LPH||1100||* 1250|
|Vert LPH||950||* 1250|
|5° Diagonal LPH||900||n/a|
|HP 812||Horiz LPH||1000||* 1250|
|Vert LPH||950||* 1200|
|5° Diagonal LPH||800||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)|
* Nyquist frequency defined as the highest spatial
frequency where the CCD can still faithfully record
image detail. Beyond the Nyquist frequency aliasing occurs.
The DX4900 performs as we had expected it to, definitely an 'average' resolution for this level of digital camera. Again, probably let down by a combination of a lens which isn't up four megapixel requirements and a lack of processing power to get the most out of the data coming from the sensor. The DX4900 also exhibits some strong moiré effects near to its extinction resolution in both directions.