Noise reduction at DVinfo.net

Jerome Marot · December 7th, 2006, 11:40 AM

Since I bought a A1 and I need to use the 12dB and 18dB gain settings, I figured I would test the noise reduction features. The A1 has 2 choices NR1 and NR2.

I had great hopes in NR1, because it is inter-frame noise reduction (averaging between successive frames) and should not decrease resolution. Frankly, those hopes were not fulfilled. NR1 is almost unusable: anything else than the lowest setting will produce obvious ghosting. A better choice is to reduce the shutter speed by 2 and to lower the gain by 3dB... Still: the "low" setting can be used if these is not too much action and pans.

A big surprise was NR2. This is intra-frame noise reduction, so it does reduce detail (and Canon says so), but the filter they use is quite clever. The filter will not decrease resolution if there is a lot of contrast, so the picture still looks sharp. You will notice a loss of detail on structures like grass, skin or wood, however. But the noise is indeed heavily reduced. Interestingly, the aspect of the remaining noise is then similar to what you get on Sony cameras like the FX-7: more blotchy chrominance noise, so I suspect this is what Sony does automatically.

So NR2 is worth a try. It is not adapted to all subjects (I would not use it if grass is in the picture, because then it shows), but it works very well. At the highest setting, it makes even 18dB almost noise free.

On a side note: this shows how difficult it is to test those cameras. NR2 is designed to not decrease resolution noticeably on resolution targets (which are high contrast), so tests would need to use special low contrast color targets. OTOH, this kind of processing is very efficient in making one believe one camera is a lot less noisy than another one, and it seems Sony does just that...

December 7th, 2006, 11:40 AM	#1
Jerome Marot Regular Crew Join Date: Jul 2006 Location: Munich (Germany) Posts: 107 Images: 4	Noise reduction Since I bought a A1 and I need to use the 12dB and 18dB gain settings, I figured I would test the noise reduction features. The A1 has 2 choices NR1 and NR2. I had great hopes in NR1, because it is inter-frame noise reduction (averaging between successive frames) and should not decrease resolution. Frankly, those hopes were not fulfilled. NR1 is almost unusable: anything else than the lowest setting will produce obvious ghosting. A better choice is to reduce the shutter speed by 2 and to lower the gain by 3dB... Still: the "low" setting can be used if these is not too much action and pans. A big surprise was NR2. This is intra-frame noise reduction, so it does reduce detail (and Canon says so), but the filter they use is quite clever. The filter will not decrease resolution if there is a lot of contrast, so the picture still looks sharp. You will notice a loss of detail on structures like grass, skin or wood, however. But the noise is indeed heavily reduced. Interestingly, the aspect of the remaining noise is then similar to what you get on Sony cameras like the FX-7: more blotchy chrominance noise, so I suspect this is what Sony does automatically. So NR2 is worth a try. It is not adapted to all subjects (I would not use it if grass is in the picture, because then it shows), but it works very well. At the highest setting, it makes even 18dB almost noise free. On a side note: this shows how difficult it is to test those cameras. NR2 is designed to not decrease resolution noticeably on resolution targets (which are high contrast), so tests would need to use special low contrast color targets. OTOH, this kind of processing is very efficient in making one believe one camera is a lot less noisy than another one, and it seems Sony does just that...