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Old Oct 13, 2007, 8:16 PM   #1
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http://www.flickr.com/photo_zoom.gne...056&size=o

File was a little too large to put on the message, so I put it in my Flickr account. I did some testing to show that the Aiptek camera's hardware is perfectly capable of doing a good digital zoom. Unfortunatly, the way the software is designed seems to prohibit it. Just to make sure you know what you are looking at here, I'll explain.

I put the camera on a tripod and I took a still image. Then I put the camera in video mode and took a few seconds of video at 1X and a few seconds at 4X. Then I took screen-captures of the video so you can see these stills. These are the pictures on the left. Now, on the right hand side, I took a paint program and reduced the image down to 640x480. Obviously, it has less compression than the video mode and looks a lot better. But the bottom-right picture tells the story. How did I get this picture? I just used my paint program and cropped out the exact same area of the 3M still image to get another 640x480 image. However, the camera never moved on the tripod the entire time any of these pictures were created. So why does the 4X zoom I did in the paint program look so much better? The only explanation I can come up with is the way the Aiptek firmware handles its zoom function. I believe the video feature starts off with a 640x480 image from the sensor (rather than a 3 MP) and when you go to zoom in, it zooms into the 640x480 image instead of using the entire sensor. It is very likely that a firmware re-write would allow the Aiptek cameras to have a decent 4X digital zoom. I may try a similar experiment with my Sanyo. However, I'm not even sure if it has a digital zoom or not, I'll have to check.
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Old Oct 14, 2007, 11:37 AM   #2
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I just performed the same test with my Sanyo CG6. Unfortunatly, it is difficult to do a straight comparison because my Sanyo won't enter digital zoom until it has reached the end of the optical zoom. So what I did was started off by zoomming to the full range of the optical before taking the 6 MP snapshot. The other thing is, I think the digital zoom on the Sanyo may be more than 4X of the Aiptek. Nevertheless, I found that the Sanyo could zoom in considerably while still giving an image that is not blocky. However, at the far limit of the digital zoom, there was some blockiness that was not observed in the zoomed in 6 MP image. Which means the Sanyo does have the same problem as the Aiptek, but not nearly as bad.

Being that the Sanyo has an optical zoom, the issue is almost pointless. However, being that these cheap Aiptek cameras depend on the digital zoom as the only one available, I would think they would put forth more effort to make it work correctly.
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Old Oct 14, 2007, 4:00 PM   #3
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I've never seen digital zoom on a camcorder that was worth using even on my Sony camcorders. Why? Because you are trying to zoom at 30 frames per second so unlike a paint program which has the luxury of analyzing the image and selecting the best zoom algorithm or use a specific one you've selected and at that it does take a little time to process. Try doing that at 30 times per second. If zoom or telephoto is important then one should get a camera that has a good optical zoom with a quality lens like a Zeiss.

At that the first thing an HD camcorder user learns is that unlike his SD camera any shake will be magnified much more when zoomed in. That's why when you see still photographers with a telephoto lens on their camera they are on a tripod and almost NEVER handheld.

Though I have a telephoto adapter for my Sony I have rarely used it. In fact most of the time I use the wide angle adapter so that I can get great shots in small quarters. And just the opposite from the telephoto the shake is even more reduced (note I turn off stabilization as it reduces resolution though this may not be so with optical stabilization).
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Old Oct 14, 2007, 6:08 PM   #4
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Quote:
Why? Because you are trying to zoom at 30 frames per second so unlike a paint program which has the luxury of analyzing the image and selecting the best zoom algorithm or use a specific one you've selected and at that it does take a little time to process.
i disagree with this. The reason digital zoom stinks on most camcorders is because the imager is designed for NTSC or PAL resolution and there usually aren't enough extra pixels to use for additional zoomed in detail. Granted, some of the newer camcorders are starting to use megapixel sensors. In the case of a hybrid that has 3 or more megapixels, a digital zoom should be easy. The idea is, pixel patterns. Obviously, when grabbing a frame the imager only uses a selected pattern of pixels to get its 640x480. All that needs to be done is use a different pattern of pixels for each zoom level. Each pattern will get closer and closer to the center of the CCD the higher the zoom level. I think the way Aiptek does it, where they zoom in on their existing 640x480 image and apply anti-aliasing to it actually uses more CPU power than the method I suggest.
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Old Oct 14, 2007, 10:10 PM   #5
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Adric, you have confirmed my suspicions about the digital zoom on the Aiptek. It always looked to me that way since as you say the zoom got blocky too quickly for the resolution of the sensor.

I have noticed that my Nokia 6682 digital zoom seems much smoother even in the video mode as if it really is user the entire sensor size and that's with only a 1.3MP sensor.

It seems that Aiptek takes shortcuts in their software. I remember the PVR model that I had in which the video quality looked over sharpened and ragged compared to their other models. I did some investigation like you (which was posted on this forum as fishycomics will confirm) and came to the conclusion that their resizing algorithm was doing a basic resizing instead of resample from the full sensor image down to 640x480

I resized some 5MP images down to 640x480 size, first using basic resizing and then resampling algorithms. The basic resized ones exactly matched in my opinion the way the video looked from the Aiptek PVR.

When I sent email to their Taiwan HQ all I got was that this was the 'moire' effect which all cameras suffer from. I of course said, not to this amount they don't but they never showed any further interest. I called Aiptek USA and again they were not interested intially although one guy there did take an interest and said he wrote a report to them about the problem. Although Aiptek never officially aknowledged the problem or ever released a firmware update to fix it, the PVR was mysteriously discontinued some time after. It looked like a simple firmware fix to me, but perhaps it was hardware related after all...
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Old Oct 15, 2007, 3:30 PM   #6
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I think you want to address your questions on the digital zoom to the folks at Ambarella instead since Aiptek probably just puts a camera together around the Ambarella's developer's kit with parts they can purchase in bulk. I doubt if Aiptek's engineers had anything to do with the zoom other than turn it on in firmware.

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Old Oct 17, 2007, 10:27 AM   #7
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hdguy wrote:
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I think you want to address your questions on the digital zoom to the folks at Ambarella instead since Aiptek probably just puts a camera together around the Ambarella's developer's kit with parts they can purchase in bulk. I doubt if Aiptek's engineers had anything to do with the zoom other than turn it on in firmware.
We're talking about the other Aiptek Camcorders not the A-HD. That is the only one that uses the Ambarella Chipset.
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Old Oct 17, 2007, 2:36 PM   #8
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Though Aiptek may have developed the complete product my bet is they even used third party chipsets and developer kits for the other cameras too. Dump the files and see if there is any notation of a third party company. Even then that ID may not be there.

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