Infrared photography

[yelvertoft]

Hello,

I didn't know if this should go in the Digital Darkroom sub forum, or the General Technique. There's a bit of both involved so I thought I'd post it here.

Some people have asked for information on how to get IR images from digital cameras, so I have put this article together.

The prerequisites: You need a camera that is sensitive to the IR spectrum and an infrared filter such as a Hoya R72. You’ll have to do your own research to see if your camera is IR sensitive but I know the Nikon D70 is pretty good with IR. Unless you live in a high IR intensity area (a.k.a. desert!) it is almost essential to use a tripod as you could well be dealing with exposures of several seconds depending on your camera and the light available. Shots are best taken at mid-day in autumn, winter or spring, you can get away with other times during the summer. There has to be a lot of IR light about, IR is NOT the same as thermal imaging. You can often take a good guess about how much visible light there is, unfortunately this isn't true for IR so take your tripod just in case.

As there is quite a lot of post processing involved, I always shoot in RAW format with infrared images, assuming I actually remember to make that adjustment on the camera! I use Adobe Camera Raw for my raw processing, but other tools such as Raw Shooter Essentials or the Pentax Photo Lab utility that was supplied with my camera (*ist DS) offer very similar facilities. Having got your infrared image, straight out of the camera, it may look something like the first shot in the series below. Hmmmm, kinda red, isn’t it?

Clearly, most of the colour information is in the red channel. Whilst IR is essentially a form of monochrome photography, there is some colour information in all three (RGB) colour channels. If you do not want to end up with a completely monochrome image, it is important to retain some information in the green and blue channels. The first step is to tweak the white balance using your raw processing tool. Adjust the colour temperature and tint sliders, whilst previewing the image and watching the three colour channel histograms (note the comment in bold above). With Adobe Camera Raw, I often select the "Auto" option from the "White Balance" drop down list. This usually gets me into the right sort of area for subsequent fine-tuning. Tweak the other sliders for exposure, shadows, brightness, etc. to get the effect you are after. Again, I often find that the "Auto" tick box gets things pretty close, often only requiring minor tweaking later. You can make all the adjustments manually and achieve the same result; it just might take a lot longer to get there. Having made adjustments to the raw image, it may well look something like the second one in the sequence below. Import this image into your image processing program.

Adjust the colour levels, using Level Adjust (not surprisingly), adjusting the histograms for each of the red, green and blue levels to get an image that may look something like the third one in the sequence below.

The next step involves swapping the information in the red and blue colour channels. This has been a real throwaway comment in other IR processing tutorials I’ve seen without giving any information on how to do this. So, I’ll try and explain in a bit more detail.

Your image-processing package must have a "channel mixer" feature to do this. Later versions of Paintshop Pro certainly offer this tool; earlier versions may also do so. I suggest you search the help file in whatever application you use for "channel mixer". Adobe Photoshop Elements does NOT have a channel mixer, but Photoshop CS and CS2 do. Again, if you have an earlier version of Photoshop, search the help file. Select the channel mixer tool and check that the Output Channel is set to Red. Move the Source Channel colour sliders so that the red is set to 0% and the blue is set to 100%. Change the Output Channel to Blue and move the Source Channel sliders so that blue is now set to 0% and red is set to 100%. Select OK. The resulting image may look something like the fourth one in the sequence below.

If the image is looking far more monochrome than you anticipated at this point, it will probably be because you have removed too much of the green and blue channel information in the White Balance adjustment stage right at the beginning. If so, go back and start again. It may sound daunting, but it will only take a few minutes to get back to this stage now you’ve learned to adjust colour levels and swap colour channels.

A bit of adjustment to the colour levels, using the Hue/Saturation tool, can now be used to tune the overall colour balance. To get the classic white foliage look of IR film shots it will probably be necessary to turn down the magenta a little. The final IR image looks like the fifth one in the sequence below.

I can only attach 5 files per post, Ill carry on with the next post!

[yelvertoft]

Remember, this is not visible spectrum stuff, so there is no reality here, it is all surreal and you can make it as wild and wacky as you like. I’ve described one way of doing the post processing, this does not mean this is the right way to do it, there is no right or wrong, it’s in your hands to create your own version of reality. The most critical phase I’ve found is the raw file white balance adjustment, that’s where it all goes pear shaped for me!

This scene looks like the sixth in the sequence below when viewed in the normal visible spectrum.

Hope somebody out there finds this useful.

Regards,

Duncan.

[Gidders]

There is also a technique that can be used to simulate infared even if your digital camera is not infared sensitive. Try this with any image with high levels of green foliage in it.

Again a lot of post processing is required and produces a monochrome end result. 1st open your image in full RGB colour. Then add a channel mixer layer. Boost the green channel to 200% and then, to keep everything at ~100% overall, reduce the other channels to minus numbers - I tend to use ~-30% red & -70% blue, and tick the monochrome box.

Next, to get the glow that you get with IR film, we need to add some blur. Go to the channels pallate, select the green channel only and apply some gaussian blur - about 5 pixels should do it. Then to make the effect less severe, reduce with and Edit > Fade Filer command to what looks right - try 25%.

Finally, IR film is very grainy so you might want to add some gaussian noise, either to the whole image or just to the green channel.

You should end up converting something from this Barn in Field 3088.jpgto something like thisBarn in Field (IR)3088.jpg The frames were added afterwards with photoshop actions.

Do you prefer the full colour or the mono?

[Don Hoey]

Cheers guys. I will definately be giving this a go.

Don

[Adey Baker]

Some compact digi-cameras are sensitive to IR - I took this a couple of years ago with a Sony S85 with an opaque IR filter held in front of the lens.

Exposure times were quite long so most of the shots were a bit blurred but this one looks quite like a typical IR mono image

[rachelita]

I also used to do a lot of infrared photography - you can see my webpage on this topic with links: http://home.primus.ca/~rachelita/rachelita.htm

i used the Oly2100UZ (a 2.1 MP camera) and the Hoya R72 filter - do not spend more than 5 minutes on editing images - you can see my gallery here:
http://home.primus.ca/~infrared/

Also concerning about article, I have to disagree about the best times to do infrared or perhaps it depends where you live - in Canada, the best is the spring and the summer, in very high sunny days - the winter light is way too low and diffused and soft and no infrared are emitted and thus do not pass through the very opaque filter.

[wolfie]

Having done a great deal of IR in the past using an Minolta D7 camera, I would agree with Rachelita, In that Spring & Summer on very sunny days are best.

I only have two samples on my hard drive which I will attach, neither of which will comply with your expectations of IR.

Harry

[yelvertoft]

Can't see that we're actually disagreeing regarding times to take pictures.

[Don Hoey]

Originally Posted by Don Hoey

Cheers guys. I will definately be giving this a go.

Don

Maybe a bit late seeing the origional date of this thread, but I am finally getting round to this.

Excellent starter for IR Duncan. It would make a good sticky to which we could add our experiences and any processing tips/tricks.

Don

[Don Hoey]

Jusy in case we get this as a sticky I am adding a link to my ' IR on the cheap ' thread as an initial contribution.
http://www.worldphotographyforum.com...ead.php?t=4494

Don