EXR Confusion not fully resolved

Started Jan 25, 2014 | Discussions thread
photoreddi Veteran Member • Posts: 7,973
Re: EXR Confusion not fully resolved

Timur Born wrote:

photoreddi wrote:

No, you relish trying to correct people but in this case it's YOU that are wrong.

I relish my daughter getting healthy, not correcting people on an anonymous forum.

You're talking about the entire sensor, ignoring or not recognizing that I wrote this :

On a pixel basis the larger M size pixels capture more photons so their DR will be greater than the L size pixels (substitute photosites for pixels here if you prefer.)

But you are right, I puzzled up your "pixel basis" statement with a "sensor basis" one. Sorry for that.

Thank you. It's good to see that unlike some, you're willing to be reasonable.


Now if you can demonstrate that M size pixels are the same size as L size pixels then maybe you have a point to make.

Here I have to disagree again, though. M size pixels are the same as L size pixels, it's still a 12 mp sensor capturing 12 mp data. It is not a 6 mp sensor where each pixel has a deeper photon well with higher linear dynamic range. Instead the 12 mp pixels are averaged down to 6 mp and then demosaiced, they are not summed up to a higher signal strength. Averaging lowers noise and thus increases signal-to-noise ratio.

No, M size pixels are not the same size as L size pixels. Pixels are (as you indicate) mathematical creations of a complex demosaicing algorithm. The photosites used to create the M size pixels are the same size as the photosites used to create L size pixels, but there are twice as many L size pixels as M size pixels so they can't be the same size. You seem to think that to create an M size pixel, the demosaicing process has to create individual L size pixels and then average them down to M size pixels. That's one way that Fuji could have done it, but it's more likely that Fuji starts by combining pixel pairs and then uses a more straightforward Bayer demosaic on the averaged pairs. This would produce higher resolution M size images than what you've suggested. Unless you have a link to a Fuji document that explicitly states how the pixels are created, I'd have to think that the Occam's Razor principle suggests that the simpler explanation (or in this case, process), while not foolproof, provides more support for my theory than yours.


You can do the very same using an L size image and downsizing it after demosaicing. The benefit of the EXR sensor based averaging is that only pixels of same filter-color and very close proximity (nearly showing the same information) are averaged. You can get an idea of post-demosaicing results by looking at the measurements of the FinePix-F800EXR at DxOmark, comparing Screen (16 mp pixel) vs. Print (8 mp averaged) results.


Could you post a link to the page that has the "mp pixel" scores along with the controls that allow Screen vs Print to be selected, or describe how to get to it? All I see are DxO's bar charts showing Overall Score, Color Depth Score, Dynamic Range Score and Low Light ISO Score. This is on the Scores page. The Measurements page makes charts available that show ISO Sensitivity, SNR 18%, Dynamic Range, Tonal Range, Color Sensitivity, Full SNR, Color Response and Full CS (Color Sensitivity), but nothing for sensor resolution.


That you appear to be supporting Joms's unsupportable statements is interesting if not amusing. Great minds think alike, or so they say.

I assume this is meant to be an intelligent but snide remark. People on this forum always amaze me with their blatant demonstration of human nature.

I've seen that sort of thing from you as well, or at least I think that I have. If not, I probably was conflating you and Trevor. Speaking of whom, I wonder if you agree with his opinion that EXR sensors have no more dynamic range than non-EXR sensors, even when EXR DR mode is considered?

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