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Lens Blur in the new Google Camera app

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Re: Lens Blur in the new Google Camera app

#151

Post by sib »

jcampbell1 wrote: post #24
sib wrote: post #18

If only they had not confused shallow depth of field with Bokeh (which is not the shallowness of the depth of field, but, rather, how out-of-focus areas are rendered), this writeup would have been much better. http://en.wikipedia.org/wiki/Bokeh Cool technology, though.

Bokeh = shallow depth of field effects The author isn't the one confused.

Bokeh is the quality of the rendering of out of focus areas. It's not just making something out of focus (or creating shallow depth of field).

'Bokeh has been defined as "the way the lens renders out-of-focus points of light".'

Re: Lens Blur in the new Google Camera app

#152

Post by hamburglar »

mikeg8 wrote: post #89
raldi wrote: post #60

Earlier quoted context omitted.

> Up until now, a decently shallow depth of field was pretty much only achievable in DSLR cameras (and compacts with sufficiently large sensor sizes, which typically cost as much as a DSLR In 2008, I had no trouble taking shallow-depth-of-field photos with a dirt-cheap Canon A570 pocket camera. For example: https://farm3.staticflickr.com/2069/2076688334_aeae12583b_b....

Your example looks fucking delicious... (currently living abroad and missing double doubles more than ever)

animal-style, no less

Re: Lens Blur in the new Google Camera app

#153

Post by SandB0x »

dperfect wrote: post #26

I believe the algorithm could be improved by applying the blur to certain areas/depths of the image without including pixels from very distant depths, and instead blurring/feathering edges with an alpha channel over those distant (large depth separation) pixels. For example, if you look at the left example photo by Rachel Been[1], the hair is blurred together with the distant tree details . If instead the algorithm d…

Occlusion boundaries are always a challenge for vision algorithms. The defects you see are probably due to incorrect depth estimates in these regions. My guess is that for efficiency on a mobile device, they are using a simple window to aggregate the SAD measurements rather than a more complex term which weights errors based on color similarity. The simpler method will not perform well at these boundaries. Getting correct depth and foreground/background separation is a chicken and egg problem, though there are papers which aim for a joint optimization.

Re: Lens Blur in the new Google Camera app

#154

Post by jychang »

kbrower wrote: post #87
theoh wrote: post #22

Earlier quoted context omitted.

I don't know for sure but the code may be derived from or related to Marc Levoy's SynthCam: https://sites.google.com/site/marclevoy/ It does similar things, and in fact I could believe it if the Google app was just a dumbed down version of the functionality intended to be usable by a wider audience.

They did hire Marc Levoy. I have been hoping for this for awhile. Can't wait for the next iteration. There are certain things you can't replicate with just a single tiny camera, but they are doing a great job! https://news.ycombinator.com/item?id=6483182

> There are certain things you can't replicate with just a single tiny camera

MOST DoF and bokeh effects in photography can't be replicated with a single small camera.

As a photographer, bokeh is surprisingly difficult to fake, and looks glaringly bad when you notice. The blur effect is due to focal distance ratio differences, and it's very difficult to determine the distance in software. Hell, it's hard to determine it with 2 lenses, as the HTC implementation does.

If you want to compare what "fake bokeh" looks like compared to real stuff, you can look at http://www.trustedreviews.com/opinions/htc-one-m8-camera-vs-... for a review of the HTC One M8, which has a 2-lens setup.

Look at this picture, for example: http://static.trustedreviews.com/94/00002b836/8517/blue-htc-... For most software, it's extremely difficult, even with distance data, to separate the bush in the back from the blue toy. As a result... messy looking blur.

Re: Lens Blur in the new Google Camera app

#155

Post by coldtea »

grecy wrote: post #145
coldtea wrote: post #141

Earlier quoted context omitted.

Huh? Noise reduction is not a no no by any means. At least in some newspapers I know. Also, I have to add that it differs for news reporting versus stuff like interview shots, travel shots etc.

> Also, I have to add that it differs for news reporting versus stuff like interview shots, travel shots etc. Right, it really depends on if the shot is being used for "news" or if it's just an artistic shot to fill space. That's why at the start of this whole thread I reference photojournalism.

>That's why at the start of this whole thread I reference photojournalism.

I saw it, but it's not that clear cut.

What you write, "an artistic shot to fill space" implies to me generic illustration pictures, which the above isn't an example of.

I think the restrictions to editing are mostly contrained for photos about stuff like politics, world affairs, crime etc -- stuff that is presented as 100% dry news.

But the term photojournalism covers other stuff too, right? Isn't, say, a travel article written by a journalist with a photographer photojournalism too? Or the images taken by a photojournalist for a piece on dance culture, the burning man, stuff like that. Or for a sports feature.

Re: Lens Blur in the new Google Camera app

#156

Post by dperfect »

aray wrote: post #51
dperfect wrote: post #26

I believe the algorithm could be improved by applying the blur to certain areas/depths of the image without including pixels from very distant depths, and instead blurring/feathering edges with an alpha channel over those distant (large depth separation) pixels. For example, if you look at the left example photo by Rachel Been[1], the hair is blurred together with the distant tree details . If instead the algorithm d…

I'd love to see some test images with that (just get a side-by-side with the app and a larger aperture camera). As I understand what you're proposing, I'm not sure it would actually be closer to what a large-aperture camera would capture. The light field from the farther depth field should be convolving with the light field from the near depth field. Still, side-by-side would be the best way to view these :) I'll do…

Here's a comparison that illustrates the behavior of foreground blur (shot with a DSLR): http://i.imgur.com/986Iv2K.jpg

You'll notice that on the bottom image, even though the foreground leaves are out of focus, the blur does not apply to the background - details in the background are still sharp, even if partially occluded by the foreground blur.

Re: Lens Blur in the new Google Camera app

#157

Post by chernand »

jcampbell1 wrote: post #24
sib wrote: post #18

If only they had not confused shallow depth of field with Bokeh (which is not the shallowness of the depth of field, but, rather, how out-of-focus areas are rendered), this writeup would have been much better. http://en.wikipedia.org/wiki/Bokeh Cool technology, though.

Bokeh = shallow depth of field effects The author isn't the one confused.

Hi,

I am the author of the Lens Blur blog post and the sentence was indeed wrong as a result of multiple edits. Bokeh and shallow depth of field are indeed two different things. By Bokeh we mean that the blur is synthesized using a disk kernel, e.g. as opposed to a Gaussian Blur. The blog is now fixed.

Re: Lens Blur in the new Google Camera app

#159

Post by acjohnson55 »

grecy wrote: post #132
acjohnson55 wrote: post #125

Earlier quoted context omitted.

Those permitted edits you mention seem to all preserve the pixel-level integrity of the image. The fact that intentional blurring does not do this seems to be a distinction to me. I think that the fact that the blur layer must be synthesized heuristically indicates that not all of the information of the final image was really captured from the real world. I suppose that resizing (resampling) an image might be said to…

>Those permitted edits you mention seem to all preserve the pixel-level integrity of the image. Curiously, you're allowed to convert color to black and white, which in my opinion is not preserving the pixel-level integrity. An algorithm is making a guess at what level of black to convert a pixel to. > Question for professionals -- how are noise reduction, masks (unsharp), etc. treated? I'm not a pro yet, but my under…

> Curiously, you're allowed to convert color to black and white, which in my opinion is not preserving the pixel-level integrity. An algorithm is making a guess at what level of black to convert a pixel to.

In the sense of pixel integrity I had in mind, a b&w conversion wouldn't be a violation. Each output pixel would be directly effected by the corresponding input pixel (Bayer interpolation notwithstanding). Image data wouldn't be moved around from one region to another.

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