Canon's "face detection" -- How does it work?! And.. is it juz a gimmick?

[David]

The Ixus850IS has this feature... Just wondering, does anyone know how it works? Is it accurate? I can't quite see how it helps during the picture taking... Useful perhaps for total newbies who don't know how to choose an appropriate focus point, and need the cam to do it for them?

And does anyone know how the IXUS800 compare with the IXUS850 at the various ISOs from 80-800? I've only seen pics from the 850. ISO1600 looks very noisy but better than nothing.

[unseen]

This is called image processing. In case you don't know, there are hundreds of people working on such things to see who give a better face recognition software.
Canon's implementation seems to be rather good. Heard the nikon ver recognizes some lampposts/round stuff as faces too..

[shojibake]

It's probably an edge detection and then comparison of objects that are round.

[Denosha]

There are algorithms that can accurately detect and track faces although how accurate/fast the tracking is also depends on how much CPU power you have to play with.

Anyway, basic face detect identifies the T-shape of the eyes, nose and mouth. It's by texture representation rather than edge detection since it uses the AC values of the horizontal, vertical and diagonal DCT blocks to come up with an energy contrast representation for faces.

Oh and the face detection on the 850IS works quite well (although people must pretty much be looking at the camera for it to work). The focus and flash exposure will be accurate for the faces that are detected. Ie shooting people in front of a heavily back-lit background with flash will result in the flash firing at the correct level to fill in the foreground faces.

[bigu2fan]

So what does the software do when it detects faces? Does it sharpen features, adjust colour, tone of skin, etc? For eg, I always find that faces in a wedding dinner setting look very 'yellow' without flash. Does face detection help? Anyone can post pictures for comparison? Thanks!

[+evenstar]

Originally Posted by bigu2fan So what does the software do when it detects faces? Does it sharpen features, adjust colour, tone of skin, etc? For eg, I always find that faces in a wedding dinner setting look very 'yellow' without flash. Does face detection help? Anyone can post pictures for comparison? Thanks!

that's WB problem. face detection is for focusing IIRC

[bigu2fan]

Originally Posted by +evenstar that's WB problem. face detection is for focusing IIRC

what is IIRC

[Hoky]

Originally Posted by +evenstar that's WB problem. face detection is for focusing IIRC

No lar... Chinese mah... yellow skin...
Sorry, yet another stressed day at work.

[Hoky]

Frankly speaking, I like the focusing "lock-on" of the Ixus 850.
It's like the missile lock-ons on Raiden (flight game)... cool man.

[user111]

its better to use old school original human eyesight to compose and focus lock. dont really like to rely on fancy stuff like face detection. lol.

[David]

Oh wow.. so cool huh.

But yah, sophisticated it may seem, why would I want the cam to "detect up to 9 faces" (as the advertisement goes) ... Is this Canon's ploy to tempt the unknowing newbie? I mean, there's usually only one main point of interest and you also have to consider depth of field right. There's also the possibility of the cam selecting a non-face or a face which you don't want to be in focus compared to another?

Wouldn't it be better to just aim the focusing point ourselves at the face we want to be focused and it is done? Don't think it takes too much time to do that.

[pokiemon]

what happens after face detection?
how does the camera do multiple focus? also it can detect the correct flash exposure for each face?

[Isaiahfortythirtyone]

my guess is that it adjusts the aperture automatically to ensure all faces are in focus. e.g. if everyone is in a straight line, it can shoot wide open at f/2.8. but if there are a few people standing 1m behind the front man, it may stop down to get all in focus.

[unseen]

Originally Posted by David Oh wow.. so cool huh. But yah, sophisticated it may seem, why would I want the cam to "detect up to 9 faces" (as the advertisement goes) ... Is this Canon's ploy to tempt the unknowing newbie? I mean, there's usually only one main point of interest and you also have to consider depth of field right. There's also the possibility of the cam selecting a non-face or a face which you don't want to be in focus compared to another? Wouldn't it be better to just aim the focusing point ourselves at the face we want to be focused and it is done? Don't think it takes too much time to do that.

We're talking about people who are happy enough with OOF images, and absolutely delighted with focused/sharper images. They can also recompose accordingly. Many PnS don't let you recompose..

[kuoann]

Its a brilliant idea, and it works too. (tried it out on the IS850)

Have you been on holiday, passed your camera to a passerby to get a shot of you and the wonderful background, only to realise later the shot was ruined because of wrong focus? I think face detection could be pretty useful in those situations.

Now, if only cameras could auto-compose as well...

[CanonEOS]

Originally Posted by David Oh wow.. so cool huh. But yah, sophisticated it may seem, why would I want the cam to "detect up to 9 faces" (as the advertisement goes) ... Is this Canon's ploy to tempt the unknowing newbie? I mean, there's usually only one main point of interest and you also have to consider depth of field right. There's also the possibility of the cam selecting a non-face or a face which you don't want to be in focus compared to another? Wouldn't it be better to just aim the focusing point ourselves at the face we want to be focused and it is done? Don't think it takes too much time to do that.

Hahaaaa, Face detection is aim at the P&S consumer in mind and not the serious photographers. Alot consumer in the market do not even know how focus properly ( my gf and mum is one of the many) and the Face detection will help this group of people significantly in taking better pictures. These people do not care abot DOF or composure. All they want is they appear nice in picture can le

[jsbn]

Originally Posted by David Oh wow.. so cool huh. But yah, sophisticated it may seem, why would I want the cam to "detect up to 9 faces" (as the advertisement goes) ... Is this Canon's ploy to tempt the unknowing newbie? I mean, there's usually only one main point of interest and you also have to consider depth of field right. There's also the possibility of the cam selecting a non-face or a face which you don't want to be in focus compared to another? Wouldn't it be better to just aim the focusing point ourselves at the face we want to be focused and it is done? Don't think it takes too much time to do that.

If u are thinking that way, perhaps u're letting ur hobby go to ur head!

Not everyone wants to hold an SLR/MF system and shoot like a professional, perfect exposure, great composition, etc at the expense of lugging a 1 to 2kg deadweight around.

What Canon is targeting are people who'd simply wanna shoot and enjoy shooting in their own capacity or just to see their pretty faces in a photo.

[+evenstar]

Originally Posted by kuoann Its a brilliant idea, and it works too. (tried it out on the IS850) Have you been on holiday, passed your camera to a passerby to get a shot of you and the wonderful background, only to realise later the shot was ruined because of wrong focus? I think face detection could be pretty useful in those situations. Now, if only cameras could auto-compose as well...

what if it focuses on other tourists beside you?

[hongjone]

Originally Posted by +evenstar what if it focuses on other tourists beside you?

Ha ha. That's right. Wonder if can do anything to upgrade my Ixus 40, to perform the same thing.

[SianZronG]

what if you are in a place with other people in the scence? wun the face detection detect other unwanted faces? haha.