Compared to the Nikon Coolpix 990 (contd.)

Distant Detail Comparison

Canon G1 @ ISO 50
  		Canon G1 @ ISO 100 Nikon Coolpix 990 @ ISO 100

Blue... Yes, the G1 did much better, I've no idea why the 990 didn't pick up the blue (ignore the top of the image because it's blocked by the cloud). The 990 does surprisingly well at ISO 100, very little visible noise, having said that the G1 ISO 50 image is still the cleanest. Neither have more or less detail, but the G1 has better colour.

Flash Comparison

Canon Powershot G1 Nikon Coolpix 990

To me, the 990 image is darker with a strange blue cast on the wall but fairly good skin tones, the G1 image is a little pale but lighter and no cast on the wall. It's tough, somewhere between the two would probably have been the perfect image. Jo would like me to point out that the "Wanted poster" pose was my idea... (d-oh).

Colour Chart Comparison

Shot in daylight, Auto White Balance, EV compensation +0.3 (all cameras), measured light ~10 EV.

Canon Powershot G1 Nikon Coolpix 990

We're only measuring colour here. RGB values below were taken 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.

  Canon PowerShot G1 Nikon Coolpix 990
Patch White 214,208,208 201,201,201
   
Middle Gray 97,96,102 104,104,104
   
Patch Red 186,33,53 223,52,58
   
Patch Green 26,149,73 5,149,63
   
Patch Blue 55,49,117 60,50,112
   

"Warmer" overall, there's a very very very slight red cast over light areas of the G1's colour patch shot, other than that it's really a matter of taste. Notice that the G1 has maintained the lower end of the gray scale better.

Resolution Comparison

Shots here are of the PIMA/ISO 12233 standard resolution test chart (more available for comparison in our comparison database). Studio light, cameras set to auto, Exposure compensation +0.7 EV for all cameras. How to read the charts: All values are 1/100 th lines/picture height/width. So the "10" value equates to 1000.

Canon PowerShot G1
Nikon Coolpix 990

Measurable findings (three measurements taken for each camera):

Camera Measurement Absolute Res. Extinction Res.
Canon
PowerShot G1		 Horiz LPH 950 1300
Vert LPH 950 1400
5o Diagonal LPH 900 n/a
Nikon
Coolpix 990		 Horiz LPH 900 1300
Vert LPH 900 1400
5o Diagonal LPH 900 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.

It was so close, I spent a long time pouring over the G1's resolution chart, it defintely has a very slight resolution edge on the 990, but it's really VERY VERY CLOSE. The trade off for that extra resolution is increased moiré (blue / yellow banding).

Red Channel Noise (Blue Sky Noise)

Something we noticed early on with the current crop of 3 megapixel cameras was a certain amount of noise in the red channel, even at normal shutter speeds. This was normally 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 image below shows the red, green and blue content of the blue & cyan patches from both the G1 and 990. We deliberately included both ISO 50 and ISO 100 samples from the G1 "to be fair" to the 990 (as any CCD will produce less noise at lower ISO's).

I think it's fairly plain to see that Canon's implementation ISO 50 virtually illiminates any noise in light blues making it the perfect choice for daylit scenes (as there'll be plenty of light to shoot at ISO 50) there's also a much better "purity" in the G1 colours, the 990's looking oddly cast. Even at ISO 100 the G1 performs better than the 990 for light blues, the 990 just pipping the G1 for dark blues.

Original test charts for download: Canon G1 ISO 50, Canon G1 ISO 100, Nikon Coolpix 990 ISO 100