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Canon dual pixel RAW, too good to be true ?
Rumor says  focus can be adjusted post shot :

  • Pixel RAW Dual : record both of one of the normal to the RAW file of the image and the parallax information (parallax information). Digital Photo Professional of the “Dual Pixel RAW Optimizer” in the can: three of image processing
    <ul><li>Image Micro-adjustment: by using the depth information, to fine-tune the maximum position of the sharpness and resolution (original: micro-adjusts the position of maximum sharpness and resolution)
  • Bokeh Shift: to change the position of the previous blur of viewpoint (original: repositions the viewpoint of foreground bokeh for a more pleasing result)
  • Ghosting Reduction: reduce the incidence of ghost and flare
[*]RAW file size
    <li>RAW: 6270 x 4480 about 36.8MB
  • DPRAW: 6270 x 4480 about 66.9MB
  • M-RAW: 5040 x 3360 about 27.7MB
  • S-RAW: 3360 x 2240 about 18.9MB

Having read it, I think the understanding might be a but optimistic. My take on it is that DPRAW will store not only the light level from conventional raw, but also the phase information in some way. I don't know if they'll store the sub-values directly, or a derived level+phase value, since the phase has to be decoded already for the AF system to use it. Phase being some value showing if that point is in focus or not, and if not, how much in which direction. The roughly doubling of file size would be consistent with that.


Now, what could you do with that data is another matter. Adding extra blur according to the defocus amount could more accurately simulate bigger apertures than without that information, but I'm less convinced in refocusing. There are ways to improve images if you know the nature of their spread (e.g. by defocus), but in my experience they aren't good enough for high grade imaging, and are particularly sensitive to noise.


If I'm not mistaken, previous dual pixel implementations have been in a single direction have they not? I would think they would need a matrix of at least two directions for improved performance.

<a class="bbc_url" href="">dA</a> Canon 7D2, 7D, 5D2, 600D, 450D, 300D IR modified, 1D, EF-S 10-18, 15-85, EF 35/2, 85/1.8, 135/2, 70-300L, 100-400L, MP-E65, Zeiss 2/50, Sigma 150 macro, 120-300/2.8, Samyang 8mm fisheye, Olympus E-P1, Panasonic 20/1.7, Sony HX9V, Fuji X100.
  I spent some time thinking about this "Dual pixel RAW" feature and it's supposed ability to change the plane of focus after the shot has been taken, I couldn't see any way it could do it, yes it can look at the image from two viewpoints per pixel site,  but how could it change the plane of focus? 

 The answer is that it can't, however it can process the two viewpoints and attempt by using it's 3D viewpoint to "boost" sharpening in front or behind the real focus plane, but that's something anyone could do in PP anyway.

 The results show that it just plain doesn't work, at least at any useful level, the changing of the bokeh does have some visible effect, but again of limited usage. The doubling of file size file size and loss of frame rate and buffer cripple it's use even further.


Tony Northrup clears up the matter in another of his well put together videos!


This of course plays nicely into the hands of Fuji owners!

Why especially Fuji owners?  :blink:

Quote:Why especially Fuji owners?  :blink:
Because Fuji owners don't need to change the focus plane, they nailed it first time!
In reality, the 5D mk IV nails focus just fine. The dual pixel thing is first and foremost for PD AF in live view (stills and video). They hapoened to think of some neat tricks one can do with the extra info. If you put focus somewhere with a Fuji and in hindsight it should be a tad different, you can't try and shift it.

Quote:In reality, the 5D mk IV nails focus just fine.
   I'm sure it does!


It's a bit like the Pentax IBS system used for preventing moiré, a hugely advertised feature....



   that no one uses! 


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