Sunday, May 25, 2008

Canon G9 at 8 MP

A reader has an interesting question regarding the Canon G9 and Konica-Minolta A2 comparison:
If you were to switch G9 to a next-down image size (8MP, no?) would it improve a quality of an image?


Would this work in the same camera (the G9) if you merely changed the settings? Would ISO400 look more like ISO 200? Could ISO 800 be used at all? How does it all compare to A2?

Interesting question!

Since I am using RAW files, I am looking at the data exactly as the sensor captured it - or at least as close as Canon will let me come. Because the sensor is physically fixed, i.e. the size of the photosites can not change because of a user setting, anything that happens when a lower resolution is selected must made to happen in software.

So I fired up Photoshop and loaded the original ISO 1600 file into ACR. (I used ISO 1600 because noise is most pronounced and anything that changes should be most visible there). I then processed the file twice:

  • The first time, I used the "Image Size" dialog to reduce the resolution to 3266x2450 (8 MP). For what it is worth, I used the "Bicubic" algorithm so that sharpening would not change the results.

  • The second time, I used ACR to reduce the resolution to 3072x2304 (7.1 MP) during raw conversion.

The usual crops are here, with the original 12 MP crop for comparison:

Canon G9 ISO 1600 12 MPCanon G9 ISO 1600 8 MPCanon G9 ISO 1600 7.1 MP
12 MP8 MP (bicubic)7.1 MP (ACR)

I do not see a real difference in noise between the three crops.

In theory, it should be possible to remove pixels from an image and use the information in those pixels to reduce noise in the remaining pixels. It seems that neither Photoshop nor ACR can do this with the provided file and parameters. I do not know if the Canon G9 can do this internally - I only shoot RAW and the G9 certainly does not do this in RAW mode.

So, unfortunately, changing the resolution of the generated file does not reduce the noise from the Canon G9 sensor. The only way to change the noise is for Canon to change the sensor.
I would gladly shoot at 8MP or even less, especially if the resulting in superior images. Who really cares for 12MP? - I would take low res low noise image over hi res hi noise any day

I agree wholeheartedly and I wish that some camera manufacturer would listen to us and start selling a useable low-noise compact camera - with fast RAW format support, of course. :)

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