Cell-Phone Cameras That Zoom

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• 	Good work but a waste of time dickcaro on 02/06/2007 at 9:22 AM
  Posts: 7 Avg Rating:	The answer to good pictures in cellphones is more pixels and digital zoom. The trend in semiconductors including image sensors is to higher density. Using this technology to get a 3:1 zoom is OK, but installing 8 megapixels and using a 3:1 digital zoom will soon be less expensive and better. Rate this comment: (Reply)

  • Re: Good work but a waste of time omarg on 02/07/2007 at 4:53 AM

    Posts: 2

    Digital zoom although a cheaper option has some serious drawbacks. Since it uses the image interpolation technology, there is a drastic reduction in image quality. Even the higher resolution cannot address this issue since the actual image layout captured by the image sensors, cannot be regained. Secondly, working with digital zoom makes the images more prone to blurring due to slight movement of the camera while capturing the image. Hence this alternate design of the camera lens can offer better solutions to the cell phone industry. Rate this comment: (Reply)

    • Re: Good work but a waste of time gaijin on 02/07/2007 at 7:32 PM

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      It think the previous comment about using say 8Mpix and digital zoom for 3 X was indicating that without interpolation this woudl lead to a theoretical resolution of 8 /sqrt 3 = 4.7Mpix. So very nearly the same resolution as zooming a 5Mpix sensor 3X. But nothing physically moves. It woudl not be more prone to hand shake effects than optical zoom, both magnify this. However the effect that neither correspondant has mentioned is that smaller pixels collect less light. The low light performance of an 8Mpix sensor in the same optical format as an 5Mpix woudl be worse. The same effect would be a problem with the research cited. The fact that 90% of light reflected off the top face may not make the image contrast look poor (although I find this difficult to believe), but it wodl most definitely affect the low light perfromance by a huge margin. I don't think it is a waste of time, but there are still problems to solve. Rate this comment: (Reply)

      • Re: Good work but a waste of time PeterPiper on 02/08/2007 at 5:37 AM

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        Using x3 digital zoom on an 8Mpixel sensor (3264 x 2448 say) you would get only 1/3^2 of the sensor resolution, so image size 1088 x 816. Zooming in to 4Mpixels only gives you x1.414 not x2, sorry (x2 would only give you a 2Mpixel image). You COULD zoom in further than 1 to 1, but you are not adding any new information, just adding more data points to a smaller and smaller raw image. Futher to the point about reduced sensitivity, another effect of the smaller pixel pitch is the lens can't resolve to that level. You could use bigger pixels, but that is more Silicon, more money, longer focal length so larger lens and shorter depth of field. Yet another issue is reduced full well capacity (means the best noise level that can be achieved is limited, the reason why higher and higher pixel count cameras are getting more noisy....). My question is, they say optical zoom. This needs a change in the characteristics of the optics, normally achieved by moving one of the lens elements. In this case, how is the 'zoom' actually achieved? I have checked this, sorry for any errors (especially spelling!). Rate this comment: (Reply)