iZoom, FZ200, LX7, FastStone - a few thoughts

Started Apr 10, 2013 | Discussions thread
OP Mikedigi Forum Pro • Posts: 10,629
Re: iZoom, FZ200, LX7, FastStone - a few thoughts

Detail Man wrote:

Mikedigi wrote:

DoctorJerry wrote:

Very well said. It is my understanding that EZ Zoom ONLY takes a central portion of the sensor which is why ther is no image degradation. It does NOT add pixels anywhere. Both iZoom and digital zoom add pixels to the image to get back to their 12mp size.

In EZ, pixels are not added to the crop.  It is just a crop.

That is precisely his point.

Yes, I was agreeing with him.

Yes, iZoom adds pixels and uses iResolution to get the business done.

i-Zoom stretches the image-data contained within pixels out into other surrounding pixels . . .

that have been added - about one-for-one in the case of 48x zoom in the FZ200.

- with particularly troubling results when the up-sampling ratio is not an integer value. Doing so seems (to me) silly given that such images are very likely to subsequently be down-sampled for display (which itself involves, up-sampling by interpolation, anti-aliasing filtering, and down-sampling by decimation).

In my tests the FZ200 at 37x iZoom upsized the 5.067mp sensor crop to 12mp.  I picked 37x as a prime number, just in case that made things more difficult.  But the results were equally good.  I have no idea how they do that.

There seems nothing magical about "i-Resolution". In fact, it actually reduces the resolution of any subject-matter existing in areas that it deems to be "low gradation". The net result is when fine detail exceeds the abilities of the image-sensor assembly to resolve it ("pixelation" effects), "i-Resolution" simply detail-smears it away. Rather unusual for a "sharpening" technique ?

I agree, when I compare iRes On with iRes Off images in general, iResolution sometimes reduces surface detail but in some cases it sharpens edges.  So whether iRes On is better or worse depends on the subject and whether surfaces or edges are more important.

It works well, better than a 3mp EZ file . . . trust me, I have used EZ for years, and I am a cynical #######.

From investigating how the FZ30/50 and LX3 accomplish "EZ Zoom", it appears that the chosen priority is that sensor-cropping is used, and down-sampling appears to only be utilized in cases of the very smallest "Picture Size" settings (i.e. 2.5 Mpixel and 3 Mpixel).

Yes, I used EZ for years and as a simple sensor crop it does what one would expect, exactly the same as a PC crop, but helping with the capture process.

Why would an image that has been up-sampled (and then subsequently down-sampling for display purposes in the end, anyway) tend to look better than an image that has been down-sampled ?

Exactly.  I thought that iZoom would be a disaster, that's why I ran my own tests.  I was surprised that the results were so good.

More re-sampling (in general) means more artifacts (particulalry when non-integer ratios are used).

Not everything, that is new, is bad.

Extreme birders use it - why would they do that, if it was incompetent?

Just to chide you a bit. This "extreme birders use it" argument seems (to me) to be a bit of a "canard" (French for duck). . . . . . . . .

Less an argument, more an additional example.  Birders want feather detail - what could be more demanding of IQ than that?

I agree with you that iZoom ought theoretically to be a disaster.  But my own tests on page 2 tell me that it isn't, and I am told here on the Forum that a lot of birders are using it, and I am claiming that many of them would recognize inferior IQ if they got it.

For me personally, it is all a non-issue.  The 25-600mm EFL lens of the FZ200 is over-the-top for me and I am unlikely to need anything over 600mm, except for fun.  I would have been happier with an ultralight development of the FZ5 with improved IQ and something like 25-400mm EFL and a weight of around 350 grammes.

My only motive here was curiosity to see how well iZoom works, and to try to understand how it works, and the comments from you and other posters have been very helpful.


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