Kodak EasyShare DX4900 Review: 12. Compared to...: Digital Photography Review

Compared to...

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.

Patch	Kodak DX4900	HP 812	Canon PowerShot S40	Minolta DiMAGE S404
Black	12,11,18	14,14,18	30,30,30	15,19,22
Middle Gray	100,98,107	87,91,94	103,102,103	70,72,87
White	198,192,197	235,242,238	215,210,211	192,191,201
Magenta	191,8,102	239,20,100	199,41,113	179,26,106
Red	198,9,45	242,10,32	196,33,42	176,29,44
Yellow	220,195,20	254,223,41	211,192,38	189,190,34
Green	0,127,57	0,132,71	33,140,67	3,113,45
Cyan	0,137,194	0,157,221	26,160,223	8,123,194
Blue	31,23,98	12,32,100	33,44,116	31,21,94

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.

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 1/100^th 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.

Kodak DX4900

HP 812

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
	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.

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.

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