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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

#81

Post by DanielBMarkham »

Lately I've been watching various TV shows that are using green screen/composite effects. At times, I felt there was some kind of weird DOF thing going on that just didn't look right.

Now I know what that is. Computational DOF. Interesting.

Along these lines, wasn't there a camera technology that came out last year that allowed total focus/DOF changes post-image-capture? It looked awesome, but IIRC, the tech was going to be several years until released.

ADD: Here it is. Would love to see this in stereo 4K: http://en.wikipedia.org/wiki/Lytro The nice thing about this tech is that in stereo, you should be able to eliminate the eyeball-focus strain that drives users crazy.

Re: Lens Blur in the new Google Camera app

#82

Post by ygra »

aray wrote: post #42
theoh wrote: post #31

Earlier quoted context omitted.

SynthCam is one, free but not open source. You might be interested in the various bits of lightfield rendering code released by Stanford: http://lightfield.stanford.edu/

Synthetic aperture-like algorithms are also common at SIGGRAPH if you go through the past two decades. A quick search didn't unearth any, but there is open source software to do parallax depth inferencing, and you could just apply proportional gaussian blur kernels to each depth segment to get a very similar effect.

Gaussian blur looks very different from the blur produced by an aperture. You need a round blur kernel, not one with a bell curve fall-off.

Re: Lens Blur in the new Google Camera app

#83

Post by theoh »

aray wrote: post #25
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.

There have been multiple implementations of this class of algorithm (collectively "synthetic aperture") using different techniques. Edit: below mentions the HTC "double camera" phones, and in fact it's also possible to create synthetic aperture photography with multiple cameras instead of moving a single camera to multiple positions. Then you have the added advantage of not needing to assume a static scene! But a sin…

Point taken. Arguably it's a case of David Pye's notion of the workmanship of certainty (in this case heavy-lifting computer vision) replacing the workmanship of risk (making adept movements of camera) But if it works better under all conditions, fine. http://en.m.wikipedia.org/wiki/David_Pye_(furniture)

Re: Lens Blur in the new Google Camera app

#84

Post by kbrower »

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…

Side by side comparison http://onionpants.s3.amazonaws.com/IMG_0455.jpg

Re: Lens Blur in the new Google Camera app

#85

Post by darkmighty »

jawns wrote: post #41
grecy wrote: post #12

We had an interesting discussion about this a few nights ago at a Photojournalism talk. In that field, digital edits are seriously banned, to the point multiple very well known photo journalists have been fired for one little use of the clone tool [1] and other minor edits. It's interesting to think I can throw an f/1.8 lens on my DSLR and take a very shallow depth of field photo, which is OK, even though it's not ve…

When you say "digital edits are seriously banned," I think that's overreaching. I'm a former newspaper editor, and "digital edits" in the form of adjusting levels, color correction, etc., are performed on every single photo. What's not allowed, as you allude to, is retouching a photo. So does introducing blur after the photo was taken count as retouching, or does it fall into the same category as color correction? It…

Yea I think it's ok to edit as long as it doesn't produce significant logical inconsistencies from the original (A=>B) - e.g. two missiles are turned into three; or it seemed to be late afternoon which can be made to seem nighttime from color balance (when that's significant).

Procedures like blurring shouldn't be able to cause those because like you mentioned the could have been done in situ with a camera, and they usually just lower the amount of information in the picture. That itself can change the interpretation of the scene (B=/>A), but to some extent this is inevitable -- and so acceptable if not overdone.

Re: Lens Blur in the new Google Camera app

#86

Post by raldi »

jwarren wrote: post #71
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....

Some things worth noting: Depth of field increases as the focus point moves deeper into the frame. Depth of field decreases as your lens length increases. Depth of field decreases as your sensor size increases. The A570 will have a relatively large sensor compared to a mobile phone, and your subject was very close to the lens. These things considered, the depth of field isn't impressively shallow. Reducing the sensor…

Good points; all my shallow-depth-of-field shots seem to be close-ups.

Re: Lens Blur in the new Google Camera app

#87

Post by kbrower »

theoh wrote: post #22
jawns wrote: post #5

Regarding the technology (achieving shallow depth of field through an algorithm), not Google's specific implementation ... 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). You can simulate it in Photoshop, but generally it takes a lot of work and the results aren't great. The "sh…

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

Re: Lens Blur in the new Google Camera app

#88

Post by georgemcbay »

alanh wrote: post #75
reustle wrote: post #67

Earlier quoted context omitted.

> It's interesting to think I can throw an f/1.8 lens on my DSLR and take a very shallow depth of field photo, which is OK, even though it's not very representative of what my eyes saw I beg to differ. Pictures with a shallow depth of field feel more real because that is how the eyes work naturally. Hold up your hand at full arms length, and focus on it with your eyes. Everything else around it is blurred.

You’re both right, to some degree. While you are correct that the eyes focus at a certain depth, much like a camera, the difference is that we can chose to focus at any depth (assuming good eyesight). This is not true of a photograph if it has no depth. (It’s also true that, if the photograph has both fore and background in focus, edges may be harder to pick out and depth harder to discern, even though we would have…

Dynamic range too. Modern digital sensors are just now approaching dynamic range similar to that of the "instantaneous" dynamic range of human eyes, but as you mentioned we don't really see images instantaneous as a camera does and what we "see" (when you include brain processing) is really essentially a stack of everything we've seen up to as much as the previous 15 seconds; and when you take that into account even the best cameras are still way off on DR.

Re: Lens Blur in the new Google Camera app

#89

Post by mikeg8 »

raldi wrote: post #60
jawns wrote: post #5

Regarding the technology (achieving shallow depth of field through an algorithm), not Google's specific implementation ... 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). You can simulate it in Photoshop, but generally it takes a lot of work and the results aren't great. The "sh…

> 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)

Re: Lens Blur in the new Google Camera app

#90

Post by pjmlp »

dannyr wrote: post #23
Spittie wrote: post #11

I find it funny that this was one of the "exclusive features" of the HTC One M8 thanks to the double camera, and days after it's release Google is giving the same ability to every Android phones. I'm sure the HTC implementation works better, but this is still impressive.

Well, only Android 4.4.x phones. But coming to other Android version.

Where do they state < 4.4 users would ever get it? I only find mentions of 4.4.
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