Compared to... (contd.)
Colour Chart Comparison
Now we can compare the IXUS 300 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 S10, 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.
|Canon Digital IXUS 300||Canon PowerShot S10|
|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 and eliminate JPEG artifacts) using the Eyedropper tool in Photoshop with a 5 by 5 Average Sample Size.
Surprisingly dull blues, indeed the IXUS 300 has done an excellent job of measuring the correct white balance, both the white and gray patches samples are virtually pure, unfortunately all the primary colours are less saturated (duller) than I would have liked to have seen (compare them to the Sony MVC-CD200), having said that they're plainly an improvement over the S10. This fitted in with what I saw in images from the camera, to give them some "zing" they tended to need a saturation boost of about +15 (Photoshop).
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.
The IXUS 300 exhibits good channel separation (colour purity) and although there is some 'grainy' noise in the red channel it's not enough to be visible in most blues. About what I'd expect of a 2 megapixel ultra-compact digital camera.
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, Exposure compensation +0.7 EV for all cameras.
|Canon Digital IXUS 300 (S300 ELPH)|
|Canon PowerShot S10|
|Nikon Coolpix 950|
Measurable findings (three measurements taken for each camera):
|Camera||Measurement||Absolute Res.||Extinction Res.|
|Canon Digital IXUS 300||Horiz LPH *||820||1000|
|5° Diagonal LPH||800||900|
|Canon PowerShot S10||Horiz LPH||850||1150|
|5° Diagonal LPH||700||n/a|
|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.
Relatively good performance, resolution is better than the now ageing Nikon Coolpix 950, notably the IXUS 300 had very slightly better horizontal resolution than vertical.