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#1
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SENSOR SIZE AND RESOLUTION
Hello everybody!
Can anyone explain how it works when a camera has an 8 mpix sensor and its owner decides to take a 1280x960 photo. In this case does the sensor use all the 8 million pixels to create a smaller photo or does it use only 1,22 pixels and which ones (from the center of the sensor? Regards! Wlady |
#2
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SENSOR SIZE AND RESOLUTION
Wladyslaw Wojciechowski wrote:
Hello everybody! Can anyone explain how it works when a camera has an 8 mpix sensor and its owner decides to take a 1280x960 photo. In this case does the sensor use all the 8 million pixels to create a smaller photo or does it use only 1,22 pixels and which ones (from the center of the sensor? First, let's assume that the "digital zoom" feature is turned off. Then, yes, the camera reads the entire 8 million pixels from the sensor. It can't just read the central area of the sensor, because the field of view would be much narrower. It can't skip some of the rows and columns either, because there wouldn't be enough information to decode the colour properly, and you could have fine detail that alternately appeared and disappeared. So it reads all the pixels from the sensors, does the colour decoding, and then mathematically reduces the image from 8 MP to 1.2 MP before saving it. Now, if you use digital zoom, the picture gets a bit more complex. Digital zoom does make the camera use a smaller central portion of the sensor. If you were using 2X digital zoom, the camera would read only the centre 1/2 of the width and 1/2 of the height of the full sensor, a total of 2 MP. This smaller image would then be scaled to 1.2 MP and saved. Dave |
#3
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SENSOR SIZE AND RESOLUTION
First, let's assume that the "digital zoom" feature is turned off.
Then, yes, the camera reads the entire 8 million pixels from the sensor. It can't just read the central area of the sensor, because the field of view would be much narrower. It can't skip some of the rows and columns either, because there wouldn't be enough information to decode the colour properly, and you could have fine detail that alternately appeared and disappeared. So it reads all the pixels from the sensors, does the colour decoding, and then mathematically reduces the image from 8 MP to 1.2 MP before saving it. Now, if you use digital zoom, the picture gets a bit more complex. Digital zoom does make the camera use a smaller central portion of the sensor. If you were using 2X digital zoom, the camera would read only the centre 1/2 of the width and 1/2 of the height of the full sensor, a total of 2 MP. This smaller image would then be scaled to 1.2 MP and saved. Dave Dave, thanks for your quick reply. Having in mind what you wrote above I wonder how it correlates with the question of noise. As I wrote in some other thread some say 'if there is visible noise while taking photos at 8 mpix just reduce the resolution to e.g. 6 mpixels and teh problem ends'. Does it mean the mathematical reduction from 8 to 6 mpix makes noise less visible as well? Besides, does this mean that to avoid noise one should make 8mpix photos only in perfect light conditions and when the light is poorer switch to 6 or 4 or even 2 megapixels? Regards, Wlady |
#4
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SENSOR SIZE AND RESOLUTION
Wladyslaw Wojciechowski wrote:
[] Dave, thanks for your quick reply. Having in mind what you wrote above I wonder how it correlates with the question of noise. As I wrote in some other thread some say 'if there is visible noise while taking photos at 8 mpix just reduce the resolution to e.g. 6 mpixels and teh problem ends'. Does it mean the mathematical reduction from 8 to 6 mpix makes noise less visible as well? Besides, does this mean that to avoid noise one should make 8mpix photos only in perfect light conditions and when the light is poorer switch to 6 or 4 or even 2 megapixels? Regards, Wlady [David, not Dave here!] Yes, by combining pixels to make a lower resolution image, you will reduce noise, but using 6MP rather than 8MP I think you would be pressed to see the difference. You can do the combining (and therefore noise reduction) in post processing as well, so still take the image at 8MP, but reduce to 2MP in post processing. Of course, by using fewer pixels, the image will not look as sharp, so you may need to consider if your viewers would prefer a sharper but noisier image to a more blurred bur more noise-free image. Different image styles may suit different subjects better as well! Cheers, David |
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