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09/23/2005 12:28:22 AM · #1 |
was reading reviews and realized that many cameras actually uses in-camera interpolation (software) to reach the claimed pixel count. This, to me at least, means quality reduced in the final photo output. Now I've got a few funny ideas and I hope you people in DPC can help answer or at least explain?
1. does that mean the best quality photo from a digicam may not be the largest photo setting available on the camera? (since its interpolated?)
2. how do we check if a particular camera uses interpolation technology?
3. will the camera still interpolate if we do not use the max photo setting? ie. capturing a 5 mp photo on a 6 mp camera?
4. is this somewhat similar to using digital zoom? (which is crap, IMHO) |
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09/25/2005 09:39:44 PM · #2 |
| bump - nobody cares? or nobody knows? :( |
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09/25/2005 09:47:26 PM · #3 |
I care, I just have no idea, as I'm sure is the same with most other people :-S
Anybody have any clue?
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09/25/2005 09:56:00 PM · #4 |
Originally posted by shadow:
was reading reviews and realized that many cameras actually uses in-camera interpolation (software) to reach the claimed pixel count. This, to me at least, means quality reduced in the final photo output. Now I've got a few funny ideas and I hope you people in DPC can help answer or at least explain?
1. does that mean the best quality photo from a digicam may not be the largest photo setting available on the camera? (since its interpolated?)
Correct. THis is done on some cheep cameras to bump up the megapixle count
2. how do we check if a particular camera uses interpolation technology?
Usually tells you on the box or manual
3. will the camera still interpolate if we do not use the max photo setting? ie. capturing a 5 mp photo on a 6 mp camera?
Usually not.
4. is this somewhat similar to using digital zoom? (which is crap, IMHO)
No it is a little different it adds pixels guessing where they should be by looking at the sourounding pixels.
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09/25/2005 09:58:22 PM · #5 |
I could swear I heard something about this somewhere else. Maybe at Steves or DPreview. I believe it's only the cheap low end cameras that do this.
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09/25/2005 10:04:35 PM · #6 |
The image is recorded red, green or blue pixels; the camera then interpolates them into an RGB pixel. (see here for more detail).
As for image size, unless the image is being bumped up to a size greater than the data captured (the manual will tell you if it is), each RGB pixel is real data -- regardless of the dimensions of the image. If the final image size is smaller than the number of pixels on the sensor, the interpolation will use more sensor pixels in the interpolation.
Interpolation is not a bad thing -- nearly everything that is done to the data before the image is completely processed (both in camera and out) is done by interpolating the result from the data of the surrounding pixels.
David
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09/25/2005 10:05:39 PM · #7 |
Interpolation happens on almost all digital cameras and is pretty much unavoidable. A couple short explorations are:
Here (Toward the bottom)
And Here |
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09/25/2005 10:06:49 PM · #8 |
Here is one:
//global.yesasia.com/en/PrdDept.aspx/pid-1004047959/section-electronics/code-c/version-all/
It should be in the advertisong of the camera, maybe in the fine print.
Edit to add another link and state that this is a differet type of interpolation and it is bad if you like quality:
//www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00CGix
Message edited by author 2005-09-25 22:08:52.
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09/25/2005 10:19:31 PM · #9 |
| Thanks for the replies! actually not only "cheap and low end" cameras do this. I was reading reviews on Finepix and some other cameras from rather reputable companies. It seems they do it to reach certain pixel counts. yes I'm aware that some 1mp cameras are being sold as 2mp camera by means of interpolation - those are obvious. I'm just interested in those 2.9mp sensors being marked as 3mp, and they are done by bigger names. Just on a personal note, I'd like to avoid these cameras in the future, is there anyway to tell? It seems the manufacturers dont label it on their specs. Only can be realized from in-depth review websites :S |
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09/25/2005 10:27:51 PM · #10 |
Fuji Super CCD's are a different story they have a different type of sensor that have a honeycomb grid, ths is done to have a wider dynamic range.
Look here |
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09/25/2005 10:36:55 PM · #11 |
With regard to bayer interpolation, this is done by ALL digital cameras, with the lone exception of those using the Foveon sensor chips (Sigma DSLRs, for instance).
Here is a rather in-depth discussion of the interpolation method.
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09/26/2005 03:35:49 AM · #12 |
The Fujis do use interpolation extensively however this does not stop at least some of them being excellent cameras eg the 602z, my father in law has one and I agree with the reviews, its a great camera. It may not have the same outright resolution as some cameras with the traditional rectangular sensor arrays and nominally the same number of megapixels but thats OK, its not priced to compete with them either. Comments I have read are that while the 602z has "6mp" interpolated from "3mp" the end result is comparable to a traditional digital camera with 4 to 5 mp, and it was priced accordingly.
I agree it is confusing for the uneducated buyer but it is very different to the cheapies with a basic 1mp sensor claiming 3mp - this is misleading. Reading reviews and fine print on the box helps here, and not buying no name products is important too.
Just to really confuse I believe if you shoot in a mode where the saved image has a lower resolution than the sensor that the camera does this by a form of interpolation too! The end use here is the most important thing, if low resolution is all you will ever need why not?
In the end the result - picture quality - is important, NOT how it was achieved. Read reviews from trusted sources before purchase. By the time the reviews are out the cameras are often not quite the latest models and better priced too :-)
Message edited by author 2005-09-26 03:44:53. |
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09/26/2005 04:24:54 AM · #13 |
| even RAW files are interpolated? |
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09/26/2005 04:37:28 AM · #14 |
Originally posted by shadow:
even RAW files are interpolated? |
No -- but the RAW converter has to interpolate the individual pixels before it is RGB (or whatever colorspace converted to). The advantage is that a desktop computer is far more powerful than a camera at calculation tasks -- thus the interpolation can be done more finely, and with more user control.
David
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