Tag Archives: software

Pocket Computational Photography

If you’ve followed this blog for a while, you may have seen my earlier posts on computational photography.  If not, you can review them at this link:  http://edrosack.com/?s=computational+photography.  The term refers to using software algorithms to supplement or replace optical capture processes.  Common examples are multi-frame panoramas, focus stacking, HDR processing, post capture focus, and other techniques.  You can read more about it at this link on Wikipedia:  https://en.wikipedia.org/wiki/Computational_photography

As phone capabilities increase, their computational photography power is growing.  Camera phones have long been able to do on the fly panorama and HDR capture.  And here’s an example of a new capability that arrived on the iPhone 7+.

BokehBokeh

Apple calls this “Portrait Mode”.  It’s available in Beta on the iPhone 7+ in the latest version of IOS.  Since the 7+ has two cameras separated by a small distance, it provides the info necessary to compute a “depth map” of pixels in the frame.  The software uses this to selectively blur pixels based on distance to add a “Bokeh” (shallow depth of field) effect that helps with subject isolation.  For comparison, here is the non-computed version of the image.  You can see that the background looks very different.

Original
Original

All isn’t perfect.  The algorithm has problems around small features at the boundaries.   Look closely at the next frame and you can see blurring issues at the edges of the reed.

Phone output
Phone output

The processing blurred parts of the reed that we wanted sharp.  For the first photo above – I cheated and used Photoshop to correct the problems.  Maybe in future versions the software will be better.

Here’s one more example.  This is Lynn, rocking an election day t-shirt.  First, the portrait mode version.

Lynn - original
Lynn – portrait mode

And finally, the original.  In this case, the software did much better, with no obvious blurring issues.  These two are straight out of the camera with no processing on my part.

Lynn - portrait mode
Lynn – original

It’s fascinating how photography and computers are merging.  For someone who started out programming a large room sized Univac in FORTRAN with punch cards, the power and ability that fits in my pocket is just stunning.  I’m glad to have it with me.

What can they possibly think of next?  Do you use computational photography techniques?  Do you like or hate them?

Thanks for stopping by and reading my blog. Now – go compute some images!

©2016, Ed Rosack. All rights reserved