Vladimir Brajovic's Shadow Illuminator
October 9, 2003 12:06 PM   Subscribe

Vladimir Brajovic does interesting research on "reflectance perception". The result: the Shadow Illuminator, a site that brings out amazing amounts of detail in the shadowy parts of your digital images.
posted by tss (23 comments total)
Disclaimer: he works at my school, and I just got back from a lecture he gave.
posted by tss at 12:08 PM on October 9, 2003

Previously known as contrast masking. This sort of thing is also built into the next version of Photoshop.
posted by y6y6y6 at 12:11 PM on October 9, 2003

Yeah, but this is a little more sophisticated. Notice that there are no settings to tweak. Go ahead--put it through its paces...
posted by tss at 12:14 PM on October 9, 2003

I did. I still like my home brewed Photoshop action better. But mainly because fine tuning seems to yeild a better result. I understand your point, and I read through the FAQ so I have a vague idea what's behind his app. It's largely the same as a constrast mask - Creating a mask that will allow you to lighten each pixel based on it's deviation from a median brightness.

It's like a contrast mask with the fine tuning striped out. I'm sure many casual users will find this useful, but it's not for serious post processing. And my understanding that some of the new digital cameras are starting to do this in camera as the picture is taken.

Cool site though. Good post.
posted by y6y6y6 at 12:25 PM on October 9, 2003

I wish he put the relevant publications online. He has a few in PDF, but this one only has the abstract (and even that is a 404).

Also, it it normal to publish a technique in a journal and to try and get a patent on it at the same time?
posted by smackfu at 12:35 PM on October 9, 2003

In the Public Gallery section of the site, the before-and-after of Gene Hackman is freaking me out. Especially with faces, removing natural lighting patterns makes an image look all wrong. Where in nature are you going to find perfectly uniform, omnidirectional light like that?
posted by samw at 2:15 PM on October 9, 2003

I can understand lightening a photograph up a touch if the original was shot incorrectly, but taking out shadows is really wrong.

That's part of a good photograph. Contrast. If you take out shadows, you take out the viewer's involvement with the photo. What you can't see draws you in.

The example of the canyon using the shadow illuminator produces a horrible image, frankly. It's all washed out, nothing to miss. Maybe the CIA or FBI would like this, but that shot wouldn't win any awards if everything is washed out like that showing everything.

I prefer my photoshop tweaks yet retaining artistic qualities. Maybe for a layperson it's satisfactory, but ughh. Nice blandness.

If I photographed a black cat in a coal mine with no lighting, what would that look like using Vlad's technology? [j/k]
posted by alicesshoe at 2:55 PM on October 9, 2003

ome of the new digital cameras are starting to do this in camera as the picture is taken.

In the talk, there were slides with schematics. Brajovic's goal is to get this working in silicon, integrated into the sensor. While this may not appeal to photographers, the benefits to robotics are pretty significant. Lots of machine vision algorithms, especially those that can run in real-time on embedded hardware, are pretty sensitive to light changes and shadows. This compensation, though it does make Gene Hackman look weird, makes the look more consistent, and in the talk one of the things that was shown was improved performance at face recognition.

The lack of tweaking with this method is appealing. You don't have to change parameters if you drive into shadows; just keep running the algorithm.

Creating a mask that will allow you to lighten each pixel

The details of the mask creation seemed to be an especially important part of the algorithim, and may be where it's most novel. It's important to make sure your mask respects object boundaries and other image details. The technique involves permitting variations in the image relative to the overall intensity in a certain region, but I forget the exact details. Interestingly, there is some neurological basis for this approach.

it it normal to publish a technique in a journal and to try and get a patent on it at the same time?

I don't think it's uncommon. I was disappointed to hear about the patent too, if only because I wanted to try it out on our open-source AIBO software. I don't think we can GPL it if it's patented, though.
posted by tss at 3:09 PM on October 9, 2003

If you register at the site, you can select the strength of the effect. If you don't register, you can still use Photoshop layers to apply the effect to a lesser strength. Actually, I think applying the processed image to the original in Soft Light mode might be fairly interesting -- it should bring out more of the large-scale features of the image while not pushing the shadows too far toward black.

When tweaking images for artistic purposes, it's usually a mistake to do just one thing and stop. Think of this algorithm in conjunction with other creative tools.
posted by kindall at 3:12 PM on October 9, 2003

"I can understand lightening a photograph up a touch if the original was shot incorrectly, but taking out shadows is really wrong."

I disagree.

The human eye and brain do this subconsciously on a constant basis. Frequently to get a picture to look more "real" you need to pull the detail out of the shadows. The best example of this is a portrait taken against a bright background. To prevent overexposing the background you need to underexpose the subject. Lightening the entire photo would wash out the background. Only by lightening the subject independently can you make the photo look more "real".
posted by y6y6y6 at 3:20 PM on October 9, 2003

It's a tool. Like any other, it will be abused, but that doesn't negate its value.
posted by rushmc at 5:06 PM on October 9, 2003


ok, I'll recall that line and say instead "lightening specific parts of an incorrectly shot photo..."
I still stand by my "taking out shadows is wrong."

I'll agree with you on pulling detail from the shadows, some though. So maybe highlight an area or part of that which is in the shadows. You know very well, bounce some light from that background, light the dark area independently.....etc.

But to completely wash out the photo overall, aaaack, ptui!

Are we talking about joe tourist photo's or some portrait studio photo in regards to that " portrait taken against a bright background"?

I'm still all for shadows. Look at that image in the shadow illuminator's photo gallery. The 7th one down. A tree trunk and branch frames the left hand side and the top with a mansion in the background.

That "corrected" photo looks crappy. The original is better.

Maybe it's just subjective, but a photo is mood, subject, lighting and not just recording "just the facts m'am".

The shadow illuminator is for those who just want the facts. Or to correct their setting mistakes and/or lack of basic photography knowlege. See same photo gallery on shadow illuminator, 5th image of sky and mountain. Wrong exposure to begin with if you wanted to actually see the face of the mountain. Would the proper exposure on the mountain wash out the sky? Sure, a tad.

Some photo's are meant to be taken at the correct moment. Wait till the sun is from the side or from behind, illuminating the mountain and you've got the correct shot, otherwise...yeah, use shadow illuminator to record those moments while travelling and you just have to squeeze off a shot.
posted by alicesshoe at 5:25 PM on October 9, 2003

yeah, use shadow illuminator to record those moments while travelling and you just have to squeeze off a shot.

That's obviously what it's intended for, and it seems to do a pretty bloody good job. Still, though, isn't it up to the artist to make the ultimate decision as to what image processing techniques they're going to use on their photos? Otherwise, uou could argue the evils of performing any kind of image enhancement. You could argue the evils of transferring an image into digital format to start with. You could argue the evils of cropping photographs - after all, if you didn't frame it correctly when you took the shot, what right have you got to change that post hoc? And, of course, who are we to be so arrogant as to attempt to capture light itself in a static medium like film? Photography itself is obviously a farce.
posted by Jimbob at 6:15 PM on October 9, 2003

Ok, it can't just me but the website seems to have completely changed its "public gallery" in the last hour. When I went there the first time they had a cathedral and a couple at the grand canyon. Now they have an airplane.
posted by dgaicun at 7:10 PM on October 9, 2003

Go ahead--put it through its paces...

Tried two different pictures. Almost imperceptible differences between the shadowed before and still-shadowed after.

posted by stavrosthewonderchicken at 7:59 PM on October 9, 2003

Did a couple experiments layering the processed and unprocessed Hackman image in Photoshop. Results here. I was fairly impressed with how well the combined images turned out.
posted by kindall at 8:26 PM on October 9, 2003

It's not just about a natural or artistic look. Revealing hidden detail is sometimes just plain useful.
posted by i_am_joe's_spleen at 8:40 PM on October 9, 2003

dgaicun - When you submit your pictures for processing, you have the option to add them to the public gallery. The new picutres people are trying out must be appearing.
posted by Jimbob at 9:46 PM on October 9, 2003

This sort of thing is also built into the next version of Photoshop.

Photoshop does this now. Test it out for yourself. Download a "dark" image, load up pshop, Adjustments/Levels, move the slider to the left a bit (0 : 1.70 : 255), then Adjustments/Auto Contrast. The image looks identical, and I'm not even working with a high-res original image like the samples are.

Very, very unimpressed.
posted by Civil_Disobedient at 10:01 PM on October 9, 2003

There is a Technical Details page comparing it to the gamma adjustment and other techniques. At least on the example shown, there's a big difference.
posted by kindall at 10:06 PM on October 9, 2003

CD: Photoshop does this now

tss: I suspect it does not, but let's try. Here is an original image from the site. Here is the Shadow Illuminator version. Here is the same image with your algorithm.

It came out better than I thought, but there are important differences. Detail is brought out more clearly in the SI version: note greater contrasts on the nearest archway, the tiny bit of tree at the extreme right of the image, and elsewhere.

I don't know for certain, but I suspect that Photoshop's Auto Contrast facility is a global change to the image. Certain relationships between distal pixels may be preserved: if pixel A is brighter than pixel B on the other side of the image, it will stay that way after Auto Contrast. SI effects graded local changes; these relationships are not preserved. In this way it is a fundamentally different operation.

CD: Very, very unimpressed.

tss: <wisconsin>oOOoooo...</wisconsin>
posted by tss at 10:38 PM on October 9, 2003

The algorithm I suggested was merely a quick 1st step, and it should be customized for the individual picture. Here's the picture you chose with a bit of customizing.

Provided there's no funny stuff going on (downsampling a higher-res pic, for example), I should probably recant my early dismissal of this software. At the very least, it does save you a couple of steps in the pshop process.

As for those of you who want shadows in your pics, you can always take the original picture, add the "fixed" picture on a layer on top of it, and show-through some of the shadows if you like.
posted by Civil_Disobedient at 1:19 AM on October 10, 2003

"Photoshop does this now."

The new Photoshop command goes way beyond what auto contrast will do. All the reviews I've read so far say it works better than any of the commercial or free software for contrast adjustments.

This thread was sort fortuitous since I've been chomping at the bit this month for Photoshop CS to come out, largely just for this feature. I do mainly natural light photos and find contrast masking improves about 10% of my photos. I really should bring a reflector, but I don't.
posted by y6y6y6 at 7:01 AM on October 10, 2003

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