Discussions

Video Encoder Sees Through Fog

Posted by Lew Payne on April 21, 2010 at 10:34am

Would someone knowledgeable care to comment on this Rohm video encoder IC, which claims to "integrate the industry's first fog reduction function along with a unique, hardware-based Adaptive Image Enhancer (AIE) that provides real-time image correction for significantly improved visibility in dark, harshly backlit, or unclear/foggy environments."

In particular, the "before" and after pics just seem too good to be true...

I cannot think of an algorithm or process where so much lost detail could be restored. Does anyone know something more about what they're doing here, and has anyone adapted this to their UAV platform for clearer video on cloudy or foggy days?

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Replies

Lew Payne May 18, 2010 at 1:35pm

Apparently, the technique for "seeing through fog" is called stochastic resonance.

The folks at Princeton have used it to do various tricks with noisy signals.

[Hats off to Jason Fleischer and Dmitry Dylov]
Gregg "Cabe" Bond April 22, 2010 at 4:54pm

Short of actual water droplet fog, most loss of contrast is due to UV screwing with sensors. Slap a UV filter in front of it and see if it knocks out some of the haze.

http://en.wikipedia.org/wiki/UV_filter

Small filters for the keychain cam optics, et al... http://www.camerafilters.com/pages/uv.aspx
Lew Payne April 22, 2010 at 11:27am

I've placed an order for two (2) BU6521KV video encoder chips. Both Future and Digikey are out of stock, but the Rohm representative has assured me they have plenty in stock and would supply them to distributors as needed. I intend to use the first one for destructive testing - that's where you inadvertently hook something up backward and blow out the chip. The second one is to do the actual testing on, once I correct my inevitable mistake.
Lew Payne April 21, 2010 at 12:19pm

Okay guys, let's not assume we're using FPV sets or some low-res video camera. In other words, let's not impose artificial limitations in order to try and attack the technology; but rather, let's investigate the technology itself.

Check out this video demonstration. Note the segments with the cars, and how the only thing left is a "swirl" of fog. It looks too good to be true, but Rohm isn't some fly-by-night company. They're big, established, and have an excellent industry reputation. Very, very curious...
Lew Payne April 21, 2010 at 11:37am

Page 3 of the spec sheet for the BU6521KV has a block diagram, which reveals that the image data is first fed to a "fog reduction function" before being fed to an AIE (auto-image enhancement) function. Therefore, the "fog reduction" function is actually more than just standard image enhancement techniques. You'll also note the BU6520KV (as opposed to 21KV) on the same page, which has AIE but lacks "fog reduction." This furthers my assumption that the "fog reduction" is more than just standard AIE techniques.

Now, the question is, does anyone have a hunch as to what this function may be doing? As I said, it's more than just AIE. Wow... I just noticed how redundant I'm being by repeating myself.
Jack Crossfire April 21, 2010 at 11:30am

A dedicated chip for auto levels for $12? It can't even do HD. Maybe if it did unsharp mask, image stacking, & stabilization.
Riccardo Kuebler April 21, 2010 at 11:22am

Mmhmm, it seems at least strange, the fog picture.
It is not fading like a usual fog image, but very uniform instead. Strange that you can see the far background. Strange that the background does not change between the two pictures. Strange that it is so well delimited.
The cabin inner is strange also.

If you try to improve contrast on a low contrast picture, the results is far away from this one.

Could it be simply a reduced contrast image (the fog one)?

Is it really possible to recreate so well contrast that isn't present at all ?

Best regards,

Ric

PICTURE.IT
Ron Jacobs April 21, 2010 at 11:06am

It defineitely won't pull out "missing" detail.

If you look closely at the image, reducing contrast and increasing "green colour would easily give you the corrected image. I guess the benefit is it does this in real time for FPV flying.

I would think it would be pushing it a bit to say it works well in dark or foggy environments, aside from making the image more "viewable" but not a better image really.

Looks interesting though.

I would think incorporating IR data might alow you to "see" through fog and in dark environments, but I don't think this does that.