iZoom, FZ200, LX7, FastStone - a few thoughts

Started Apr 10, 2013 | Discussions thread
Detail Man
Detail Man Forum Pro • Posts: 16,676
Re: iZoom, FZ200, LX7, FastStone - a few thoughts

Ronomy wrote:

Detail Man wrote:

Ronomy wrote:

DoctorJerry wrote:

Nice comparisons BUT for me I would rather try EZ ZOOM first.  The extended range youreducing just cropping out the central portion of the sensor ( goingdown from 12 mp to 8 or 5mp) gives better results than any of the digital zoom variations in my opinion.

I used 3mp and 5mp EZ Zoom a lot with my FZ8 and FZ38 and that was my start point for looking at iZoom.

With the FZ200, 5mp EZ gives me 37.5x zoom and a 5mp file.  iZoom at 37x or 48mp or whatever between 24x and 48x gives me a 12mp file.

That would be meaningless if it gave inferior quality, but the iZoom pics I have shown here compare very favourably with the 24x normal zoom pics, it seems to me.

It seems that it does not just insert extra pixels, the iResolution is said to balance noise and sharpening. But I don't know the technology of it.


My problem with EZ zoom is when less than 24x you files are a lower res than the sensor. Why throw away resolution when you have izoom to keep using 12MP from 25mm to 600mm?

EZ Zoom uses sensor-cropping in combination with optical zoom, and only in some situations down-samples the recorded images. I-Zoom and Digital Zoom use the sensor-cropping and up-sample the result to larger pixel-sizes.

Up-sampling does not restore sensor resolution lost due to sensor-cropping, whatsoever ...

What counts is which approach is reducing loss of sensor resolution the least by minimizing sensor-cropping for the same composite Zoom Factor. Reduced sensor resolution is worse than down-sampling - because it limits the image-data gathered in the first place, whereas down-sampling is able to include the image-data gathered by the image-sensor (in the process of interpolation followed by anti-alias filtering followed by decimation to lower pixel-resolution).

Plus you get cropped raw files with izoom if you want to shoot raw.

Granted. It's too bad that Panasonic does not allow the same for EZ Zoom (and Digital Zoom?).

There is no change in how much of the sensor is used while in EZ.

What particular camera model(s) are you discussing ? I found the implementation of EZ Zoom in the LX3 to be rather different from its implementation on the FZ30 and FZ50. Have you verified the amount of optical zoom used by looking at the Focal Length in the EXIF portion of the image-file meta-data ? Since the display of the Zoom Factor has zero digit resolution to the right of the decimal place, how were you able to determine the exact Zoom Factors (i.e., the Zoom Factor could be anything between 1.0 and 2.0 when the display shows "1.0" and anything between 2.0 and 3.0 when the display shows "2.0").

If you set it to 5MP when you are at 25mm your throwing away resolution.

True. That is why I do not myself use modes that sensor-crop at all (or that down-sample). I understand the desire to see the target "bigger" in the preview - and the metering may not be different - but less photo-sites are available to the CDAF system to perform accurate AF ...

Your using the same 12MP of the sensor and the camera is downresing it to 5MP.  So the entire range of 25mm to 600mm you are throwing away resolution.  I would rather use izoom.  At least your looking at the full 12MP from 25mm to 600mm.  Above 24x you are cropping in the EZ and izoom setting.  The only difference is instead of going up to 12MP it goes down to 5MP until it hits 5MP area of the sensor which is 37.5x zoom.

I understand and acknowledge your point there. Better that such things occur at full zoom only.

What might be useful with EZ is the downresing may help clean up noise but your still throwing away resolution in the primary optical zoom range with is 25mm to 600mm.  That never changes.

Down-sampling shifts both the desired signal and the undesired noise downward in spatial-frequency. It can in some cases appear to improve the Signal/Noise Ratio in cases where the visible noise is high spatial frequency relative to the signal, and as a result of down-sizing is less visible due to print/display resolution limits and/or the visual acuity of the viewer.

Down-sampling does, however, combine information from multiple photo-sites into single photo-sites - something that is not the case for individual photo-sites on a cropped image-sensor. Up-sampling by interpolation adds no additional image-data at all (as well as creating artifacts). Up-sampling does not itself cause aliasing - but its use can magnify the effects of aliasing that occurs at the photo-site level (relative to the image-frame size as a reference).

EZ doesn't add any more optical zoom...your just cropping the sensor.

Correct. The same is also true of "i-Zoom" and "Digital Zoom" - so they are all the same where it comes to photo-site resolution on the image-sensor. I am no fan of the down-sampling that EZ Zoom modes perform myself (and do not use them). However, sensor-cropping (while decreasing the FOV) reduces resolution in even more significant ways, and having that sensor-cropped image-data up-sampled is rather silly, given that the image is quiet likely to be displayed at pixel-dimensions that are themselves (even) lower than the sensor-cropped pixel-dimensions.

All re-sampling adds some artifacts. Up-sampling only to then later down-sample seems undesirable.

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