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Oleg2010 05-12-2018 06:32 AM

Manual white balance in infrared photography
 
Hello,
how manual white balance in infrared photography establish?
use foliage, grass or trees?

nu2scene 05-12-2018 09:08 AM

Re: Manual white balance in infrared photography
 
Use some grass or other live green foliage to set your WB. They say to set the WB for each image you take. I usually set the WB for each set of images I take in one area. When I get to a new area, I reset the WB again.

When I get home, I adjust WB twice for each inage. I adjust WB in Nikon software, and save the image as a tiff. Then take the tiff image into PS, and adjust the WB again.

Oleg2010 05-12-2018 09:45 AM

Re: Manual white balance in infrared photography
 
Quote:

Originally Posted by nu2scene (Post 2389753)
Use some grass or other live green foliage to set your WB. They say to set the WB for each image you take. I usually set the WB for each set of images I take in one area. When I get to a new area, I reset the WB again.

When I get home, I adjust WB twice for each inage. I adjust WB in Nikon software, and save the image as a tiff. Then take the tiff image into PS, and adjust the WB again.

Thanks,Rob :afro:
very valuable advice

what EXIF, when taking pictures live green for WB?

nu2scene 05-12-2018 04:19 PM

Re: Manual white balance in infrared photography
 
Hmm, Iím not sure I understand your question.

What I do, is go walking and when I find whatever Iím taking a picture of, I point my camera at something like leaves or grass. Something thatís green and alive. It has to be a living plant of some kind. Then I white balance the camera. I try to find the live plant to be in the same light as whatever youíre photographing. Every camera does WB different, so youíll have to see how your camera does it.

When youíre done with the WB, look at your histogram and make sure you are not clipping your shadows or highlights. The exposure of your WB does make a difference to the end result of your image. So if you are clipping, adjust your exposure and do a WB again.

When I get home, I open the image in Nikon software to WB the image. I save it as a tiff. Then I open the image in Adobe Camera Raw and WB the image again. In ACR I use the WB tool. But I donít just single click on it. I click and drag it over the entire image. That way itíll WB the entire image, not just off the one small area.

Then I edit the photo after the WB is taken care of. Itís very important to get the WB fixed first. It will effect everything else when you edit the image. Hope that makes some sense.

Oleg2010 05-12-2018 11:50 PM

Re: Manual white balance in infrared photography
 
Hello Rob,
Quote:

Originally Posted by nu2scene (Post 2389786)
Hmm, Iím not sure I understand your question.

What I do, is go walking and when I find whatever Iím taking a picture of, I point my camera at something like leaves or grass. Something thatís green and alive. It has to be a living plant of some kind. Then I white balance the camera. I try to find the live plant to be in the same light as whatever youíre photographing. Every camera does WB different, so youíll have to see how your camera does it.

When youíre done with the WB, look at your histogram and make sure you are not clipping your shadows or highlights. The exposure of your WB does make a difference to the end result of your image. So if you are clipping, adjust your exposure and do a WB again.

When I get home, I open the image in Nikon software to WB the image. I save it as a tiff. Then I open the image in Adobe Camera Raw and WB the image again. In ACR I use the WB tool. But I donít just single click on it. I click and drag it over the entire image. That way itíll WB the entire image, not just off the one small area.

Then I edit the photo after the WB is taken care of. Itís very important to get the WB fixed first. It will effect everything else when you edit the image. Hope that makes some sense.

Thanks,very useful information!I'll attend have a lash at
:thumbup:

scoundrel1728 05-13-2018 01:05 AM

Re: Manual white balance in infrared photography
 
White balance also depends a lot on the infrared filtering. For an infrared filter with an 830 nm cutoff, all three of the color channels have nearly identical spectral response, so such images are basically monochrome. You can set the white balance on those once to produce a color-neutral image and forget it thereafter.


Another popular infrared filter type is one with a 720 mm cutoff. like the 830 nm cutoff filter, the 720 mm cutoff is very close to the border between infrared and visible light. in fact, it is possible the eye to see a very little far-red light through such a filter, but the amount that leaks through is effectively negligible. However, unlike the 830 mm filter, the red channel of the imagers in most infrared-modified cameras is fully sensitive to the band from 720 to 850 nm, whereas the blue and green channels are not. This gives the possibility of two complementary "colors" in the infrared band, one from 720-850 nm; the other from 850 nm and tapering off to a low sensitivity that cuts off over a band of 1100 to 1300 nm or so. If left unaltered, the band near the visible end will render as red, whereas the longer band will be neutral. This can be made more like complementary colors by giving an overall blue-green cast to the image, the amount being dependent on the subject. This can be enhanced and altered in post processing by increasing the saturation and rotating the colors around thee color wheel if desired. Because blue sky typically renders as red when taken with a camera with 720 nm cutoff filter, people often rotate the red hue about 180 degrees so the sky renders as a more natural-looking blue-green hue.


http://www.photocamel.com/gallery/da...HiFromJohn.jpg


From an unmodified Nilon Coolpix 950 camera with an R72 (720 mm cutoff infrared-pass) filter on the front. The 950 is an old camera with infrared blocking leaky enough to be used as an infrared camera without a tripod.

The wall in the background is yellow and the bars on the screen door are white. They show up as reddish because they are lit with skylight with more short than long wave length. The shirt is medium-dark blue-green under visible light, hence reflect minimal short-wavelength (<850 nm) infrared light but still reflects longer IR light strongly. Although it looks blue-green in this image, it is only in contrast to the reddish cast of the remainder of the image. An image sample of the shirt shows it to be rendered as neutral gray.



Unlike the previous two filters, the 650 nm and 580 nm cutoff filters produce not "pure" infrared images but hybrid visible-IR images. The 650 nm encroaches enough into the visible region to pass the red light of a red laser pointer or, perhaps at reduced intensity, the light of a red LED, but not much more than that. However, for most objects, the spectral reflectance/emission characteristics don't differ much between the visible and the very near infrared part of the spectrum, and the light does not encroach enough into the visible part of the spectrum for the visible part to excite the green or blue color channels of the imager much. Images taken with the 650 nm cutoff filter can therefore be expected to look much like each other, barring narrow-bandwidth emitters like red/infrared LEDs or red semiconductor lasers.


The 580 nm cutoff filter, cutting off about the yellow part of the spectrum, is another kettle of fish. That one encroaches into the visible part of the spectrum far enough to pass yellow light such as that from a sodium vapor lamp. The green channel of the imager can also pick up yellow light, so you can expect oranges and yellows to show up in your image looking like oranges and yellows. I have no experience handling such hybrid visible/infrared images, so I can offer no advice for color-balancing them.

Narsuitus 05-16-2018 01:23 PM

Re: Manual white balance in infrared photography
 
scoundrel1728,

Thanks for a very useful writeup. I am saving it.

Oleg2010 05-16-2018 01:32 PM

Re: Manual white balance in infrared photography
 
scoundrel1728,

Thank you very much, very valuable advice, quite interesting !!

maxcoolzero 05-25-2018 03:38 AM

Re: Manual white balance in infrared photography
 
Wow. I have never heard about using grass or leaves for WB. I am a newbie, so, please do not judge. Thank for the tip though.

Oleg2010 05-25-2018 03:43 AM

Re: Manual white balance in infrared photography
 
Quote:

Originally Posted by maxcoolzero (Post 2390759)
Wow. I have never heard about using grass or leaves for WB. I am a newbie, so, please do not judge. Thank for the tip though.

Hi,

me too.;-)


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