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IR - can it be made into colour?

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    Overread
    Overread  63768 forum posts England18 Constructive Critique Points
    18 May 2011 - 7:04 PM

    Ok musing thoughts here . Simply put is it possible to take a photo in IR (film/digital) and then adjust it to present the photo as a normal colour exposure? I know they can take old B&W film and turn it into colour via a tinting method - but what about IR and the digital world?

    Last Modified By Overread at 18 May 2011 - 7:04 PM
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    mlewis
    mlewis  91476 forum posts United Kingdom
    18 May 2011 - 7:38 PM

    IR photos don't have to be B&W. Once upon a time you could get colour IR film and all digital photos are colour until you convert them to B&W (yourself after taking them or by telling the camera to do it when it is set to jpg.)

    ianrobinson
    ianrobinson e2 Member 41107 forum postsianrobinson vcard United Kingdom8 Constructive Critique Points
    18 May 2011 - 8:34 PM

    i agree with mlewis you have to convert ir into b&w or colour swap for more of a colour enhancement.
    heres a couple of images i have taken with my canon 450d converted to Infra red.
    2-vampiregirls-edited-1-copy-edited-1.jpg
    This is an image taken in Infra-red then used the colour swap in ps to achieve the desired colour.

    1-img-1394-edited-1.jpg
    This is Infra red converted to mono.


    if you wish to see any more examples i will be pleased to upload them for you to view.
    as you can see portraits become vampiretraits. IR turns skin to porcaline.
    img-1610-edited-1.jpg

    Overread
    Overread  63768 forum posts England18 Constructive Critique Points
    18 May 2011 - 8:36 PM

    Hmm so whilst one can get colour its not "true" colour as our eyes typically see the scene? So is there any way to take the IR shots and have them show the equivalent true colours our eyes would normally see from regular light?

    Nick_w
    Nick_w e2 Member 73882 forum postsNick_w vcard England99 Constructive Critique Points
    18 May 2011 - 9:34 PM

    The simple answer is no.

    A camera converted to IR records the light in the infrared part of the spectrum. You have an IR filter either internally or internally ( preferable) this blocks out most of the visible light and only records IR part of the spectrum.

    You cannot then get any information that wasn't recorded in the first place.

    User_Removed
    18 May 2011 - 11:07 PM


    Quote: Hmm so whilst one can get colour its not "true" colour as our eyes typically see the scene? So is there any way to take the IR shots and have them show the equivalent true colours our eyes would normally see from regular light?

    Precisely. Because in IR photography you are not using the visible spectrum as our eyes see it but, rather, light of a frequency beyond the ability of our eyes to detect (although we will feel some IR as heat).

    Basically, the sun emits a wide range of light frequencies. As well as our visibly spectrum, there is ultra-violet, whih we can't see and infra-red which we can't see. But those frequencies are reflected off solid objects in much the same way as visible light and can be detected by film or a digital sensor designed to record them. But, by definition, those frequencies have got no colours that our eyes could detect.

    Overread
    Overread  63768 forum posts England18 Constructive Critique Points
    18 May 2011 - 11:18 PM

    Hmm so there is no way that the variation in reflection of IR light is in any way linked to the colour of the subject that it is reflected off - and thus able to reverse back to give a colour image from an IR shot.

    A shame since I know they have done something similar with that on old black and white films to get colour versions.

    Overread
    Overread  63768 forum posts England18 Constructive Critique Points
    19 May 2011 - 12:58 AM

    *dregs up memories of school physics* ahh yes I'd forgotten about the heat factor involved with IR light! I guess that does pretty much end the idea of trying to tint it into "real" colour as our eyes see it - since any difference isn't just linked to the reflective nature of the surface but also its condition at the time.

    And for those wondering why someone would want to use IR to get back to normal colours rather than just shoot normal; its part of my plan to (one day) get hold of a DSLR with liveview (probably one of the rebels for cheapness and cheap video); mod it for IR photography and then get a couple of IR spotlamps - set the whole thing up and have a good quality nightvision based camera setup (liveview needed so that I can "see" at night since the viewfinder would be rather dark to see through - since I can't see IR light itself).

    User_Removed
    19 May 2011 - 8:43 AM

    The other thing to remember is that colour (as we see it and think about it) is actually a negative concept. If an object that is illuminated by "white" light appears to be "red", that is because it has absorbed all of the other colours of the visible spectrum.

    It is the colours that we see that make up white light. If you use IR to "illuminate" a scene in the dark, then there is no white light around - and therefore no colours. So your IR-illuminated scene cannot show colours.

    Don't worry about the school physics. It is over 50 years since I played with a gold leaf electroscope in a school physics lab and I can still surprise myself with what I occasionally recall.

    bugdozer
    bugdozer  1184 forum posts2 Constructive Critique Points
    19 May 2011 - 1:44 PM

    @ Chris_L: The spectrum of infrared that we normally associate with heat is very, very far from that picked up by the camera sensor. The infrared DSLRs and infrared film pick up is very close to the visible spectrum, and the only time you'd pick up IR from heat is if an object was heated nearly to the point at which it would begin to glow visibly red... just before it reaches visible red glow it begins to glow in the "camera IR" range. As you can imagine, that's pretty hot. Anything cooler than that will not emit radiation of a short enough wavelength to see.

    The other interesting thing about trying to get "true" colour infrared, is that you can't even divide the different wavelengths of IR that the camera picks up... looking at my histogram for colours on a raw IR image it shows the red sensor picking up most, but blue and green are recorded as well, clearly not really blue and green as we see them but part of the IR spectrum the camera "thinks" is those colours. Add to that that some visible wavelengths of red do leak slightly through IR filters (I can see through mine on bright days!) and the whole recording of colour becomes an inseperable mishmash. This is why the colours the camera decides to assign to the image will be almost impossible to truly turn into an accurate representation of actual relative wavelength.

    User_Removed
    20 May 2011 - 10:05 AM

    I think that's correct, Chris. Special "night vision" cameras work in a number of different ways. Some pick up heat emissions (like the PIR on a security light) while others use their own IR sources and yet others simply intensify what little ambient light there may be.

    When we, as photographers, talk about IR, we are usually meaning light around the 700nm frequency which is just outside the visible spectrum (as Bugdozer suggests). That range is used a lot in specialist astrophotography as it is a natural light frequency emitted by some electron states in hydrogen atoms and having a camera sensor that will pick it up greatly enhances photographs of "outer space".

    mlewis
    mlewis  91476 forum posts United Kingdom
    20 May 2011 - 4:14 PM


    Quote: Hmm so there is no way that the variation in reflection of IR light is in any way linked to the colour of the subject that it is reflected off - and thus able to reverse back to give a colour image from an IR shot.

    Nope. For example, green leaves tend to come out white in IR pictures as the chlorophyll reflects a lot of IR radiation. This is in no way related to how green they appear to us.

    The whole point of IR photography is to get different results than those from visible light photography so you wouldn't want to do this anyway.

    Overread
    Overread  63768 forum posts England18 Constructive Critique Points
    20 May 2011 - 5:24 PM

    Chris - yes that is my intent - but also with a setup that offers the least amount of disturbance to the wildlife itself; hence the idea of using IR light and lighting rather than using regular spotlights and flash at night time (whilst such setups do work, they involve a level of disturbance on the subject and can limit where you employ such methods - eg you won't want to use floodlights and flash right over the den of an animal - but can happily use them in more open areas where the animals might come to feed (food lures also help)).

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