Minolta DiMAGE 7i Review: Digital Photography Review

Compared to...

Here we can compare, using results from our review archives, the colour reproduction and resolution of the Minolta DiMAGE 7i to three other five megapixel digital cameras: Sony DSC-F707, Nikon Coolpix 5000 and Olympus E-20.

Colour Chart Comparison

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.


Minolta DiMAGE 7i	Sony DSC-F707

Nikon Coolpix 5000	Olympus E-20

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	Minolta DiMAGE 7i	Sony DSC-F707	Nikon Coolpix 5000	Olympus E-20
Black	28,31,27	18,18,20	19,20,19	31,29,32
Middle Gray	95,97,91	80,89,91	91,91,91	92,92,96
White	221,222,217	176,189,190	209,209,205	201,203,205
Magenta	199,52,104	182,16,82	219,37,93	184,31,102
Red	197,39,45	178,9,4	207,26,23	182,30,43
Yellow	219,206,58	175,180,37	212,189,47	201,193,55
Green	47,140,77	8,135,66	0,130,68	25,125,76
Cyan	54,169,206	12,148,198	1,153,200	26,137,193
Blue	57,55,106	36,21,98	33,44,98	50,34,103

As you can see the DiMAGE 7i has a fairly neutral colour balance with no preference given to any particular colour and fairly mild colour saturation. Remember that if you prefer more vivid colour output you can simply increase the colour saturation setting to +1, +2 or +3.

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.

Minolta DiMAGE 7i

Sony DSC-F707

Nikon Coolpix 5000

Olympus E-20

Measurable findings (three measurements taken for each camera):

Camera	Measurement	Absolute Res.	Extinction Res.
Minolta DiMAGE 7i	Horiz LPH	* 1300	1450
	Vert LPH	* 1150	1450
	5° Diagonal LPH	900	-
Sony DSC-F707	Horiz LPH	1450	1800
	Vert LPH	1300	1800
	5° Diagonal LPH	+ 1000	-
Nikon Coolpix 5000	Horiz LPH	* 1350	1500
	Vert LPH	* 1200	1500
	5° Diagonal LPH	+ 1000	-
Olympus E-20	Horiz LPH	* 1350	1650
	Vert LPH	* 1300	1650
	5° Diagonal LPH	+ 1000	-

* Moiré becomes visible, + Chart maximum

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.

Not surprisingly the DiMAGE 7i produced identical resolution to the DiMAGE 7. This places it just below the Coolpix 5000 and quite a way away from the DSC-F707 which now seems to be even more remarkable in its ability to make the most from that five megapixel sensor. It's a shame that Minolta didn't use this update as an opportunity to improve image resolution (which is clearly a function of the camera's Bayer interpolation, the lens is good enough).