The Samovar


HDR with a crappy mobile phone camera
June 16, 2008, 10:26 pm
Filed under: Frivolity | Tags: , , ,

I can’t be bothered to carry a camera around with me wherever I go, but my mobile phone camera produces pretty shitty images, especially in low light levels. Here’s an example of my living room with normal indoor lights:

You can probably see the noisy image at this reduced size, but if we zoom into the full resolution it gets much worse. Take a look at the teapot:

A couple of days ago it struck me that it ought to be possible, in principle, to take multiple photos of the same scene and have some software align them as best as possible, do some sort of averaging process and eliminate the noise. I’d heard about high dynamic range imaging (HDRI) before and it seemed like the sort of software techniques you’d need for that would be similar to the problem I’m set myself. And sure enough, they are, and it turns out Adobe Photoshop CS3 has some tools for this built in. So what I did was to take 13 pictures from the same place, each one with a different brightness level (to try to capture details at all the different light levels), and merge them together using Photoshop’s “Merge to HDR” tool. Once the image is merged into HDR, you show it to someone on a standard dynamic range monitor (i.e. everyone), you need to convert it to a normal dynamic range image, and there are various ways to do this. I just tried Photoshop’s default setting, and it’s “highlight compression” setting, and here are the results:

As you can probably see, the detail is much clearer and there’s much less noise. This is even clearer on a close up, take a look at the teapot in the new version:

Impressive!

If you have Photoshop, it’s only a matter of a few minutes to load these pictures in to do this, and there may well be free software out there that does the same thing. The biggest problem with this way of getting decent pictures out of a mobile phone camera is that you have to take the same picture from roughly the same angle lots of times. Sometimes you can do this, but sometimes it’s a bit more difficult. Fortunately, my phone has a ‘burst mode’, which takes 4 pictures in very quick succession. It’s still not going to be any good for a scene with moving objects in it (because they will just blur), but it takes the hassle out of taking the same picture over and over.

Anyway, for future food and cake pictures on this blog (always taken with my phone because I don’t own a camera), expect the quality to be much better now that I know about this HDR technique.

Does anyone else have any tips for getting the best out of a mobile phone camera? Mine’s a Sony Ericsson K750i incidentally. And just to finish up with, here’s a gallery including the full 1600x1200ish photos so you can look at the detail close up.

Update. I just added three new pics to the gallery, two of books and tea where I took 16 images all at the same brightness level and merged them to HDR, and another one of the living room but with different and slightly more natural looking colours.

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5 Comments

That’s very impressive. If you took a succession of photos similar low-light conditions how would it have looked?

Comment by Colm

Hey Colm, not sure I understand your question. Maybe I explained myself badly in the entry above, all of those pictures were taken at the same light level (night with electric lights). The only thing I changed was the brightness setting on my phone. I’m not sure exactly what this corresponds to. I think it’s more complicated than just changing the exposure time because it seems to do some post-processing on the picture, but the effect is fairly similar. I did another one where I didn’t change the brightness setting on the phone, and it worked very nicely, but obviously like any normal photo it can’t deal with the fact that you have a very bright light source. I just uploaded three new pics to the gallery on the entry above. For the tea and books one, I took 16 photos using the burst mode on my camera (it takes 4 at a time, and I used it 4 times), all the same brightness level. You can see the difference is pretty impressive again!

Incidentally, if you have a proper camera instead of a mobile phone one, you can do extraordinary things with HDR. Take a look at the wiki entry I linked to.

Comment by Dan | thesamovar

Neat! Presumably you can do the same with The GIMP?

I reckon your moaning a bit about your Cameraphone, mind. It was practically free wasn’t it? And way better than an instamatic. Mine is in no way SotA…but I’m well impressed. And with a 1GB miniSD cards @ 4.99 in Woolies…

My photoblog:
Check out especially the goregoous West Highland Way shots:
http://www.flickr.com/photos/edwardthebonobo/sets

But, aye, low light’s a bitch.

Comment by Edward the Bonobo

Sadly the GIMP is not so good at HDR because it doesn’t have support for 16/32 bit channels as Photoshop does. You can do it by hand, but I don’t know how well that works. There is some free software to download that does HDR but I haven’t tried it.

On the phonecam, it’s fine in daylight but pretty hopeless otherwise (see above).

Comment by Dan | thesamovar

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