Compared to... (contd.)
Colour Chart Comparison
Now we can compare the C-700UZ to a couple of other cameras, using samples from our test archives we will now compare its image quality (colour and resolution) to the Canon PowerShot A20, Sony MVC-CD200 and Nikon Coolpix 950.
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.
|Olympus C-700UZ||Canon PowerShot A20|
|Sony MVC-CD200||Nikon Coolpix 950|
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.
The C-700 UZ does well, overall colours are good, an even balance across the board. As we spotted on the previous page greens have a slight yellow taint (though no more in % terms than other digital's).
Red Channel Noise
Something we've commented on previously is noise in the red colour channel in what should be pure blues. This was most visible in the light blue of skies or painted walls. Our colour patch test chart turned out to be a good "leveller" and a way to measure the performance of one camera to the next.
The samples below are of 40 x 40 blocks cropped from the colour comparison charts above of the Blue and Cyan patches, each block is then broken down into it's red green and blue channels and reflected as such directly below.
Blues are definitely better (more saturated) than the Canon A20, however they do seem to contain a fair amount of noise in the red channel.
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.
|Olympus C-700 UZ|
|Canon PowerShot A20|
|Nikon Coolpix 950|
Measurable findings (three measurements taken for each camera):
|Camera||Measurement||Absolute Res.||Extinction Res.|
|Olympus C-700 UZ||Horiz LPH *||800||1000|
|Vert LPH *||800||1050|
|5° Diagonal LPH *||700||900|
|Canon PowerShot A20||Horiz LPH *||820||1000|
|5° Diagonal LPH||800||900|
|Sony MVC-CD200||Horiz LPH *||850||1050|
|5° Diagonal LPH||800||900|
|Nikon Coolpix 950||Horiz LPH||750||1050|
|5° Diagonal LPH||800||n/a|
Definition of terms:
|LPH||Lines per Picture Height (to allow for different aspect ratios the measurement is the same for horizontal and vertical)|
|5o Diagonal||Lines set at 5o 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 moiré effect on the C-700 UZ resolution charts is probably the worse I've seen, not a performance I'd expect of a second generation 2 megapixel and certainly not in line with other (even lesser priced) 2 megapixels. Resolution is better than the two year old Coolpix 950 but less than the A20 and CD200, probably what we'd expect of a complex 10x optical zoom.
If you take a closer look at the resolution charts it's also worth noting that the lens exhibits a certain amount of softness in the corners.