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I am photographing plants that are grown in a greenhouse. The plants are grown under High Intensity Discharge Lights, specifically Metal Halide and/or High Pressure Sodium. When I photograph these plants they come out looking yellow vs their natural color. Using raw I can typically recover the photos back to their natural color but not always. Of course this method has me processing every single photo to some extent.

My question is are there filters or methods for shooting under High Intensity Discharge Lights that can prevent the yellowing of the photo.

I am using a Nikon D5100 and shooting in raw.

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  • Related: How can I reduce the effect of sodium vapor street lights in night photography? - yea, its not night photography you are interested in, but Sodium vapor lights are very specific and quite filterable. – user13451 Oct 26 '14 at 2:15
  • @MichaelT Low Pressure Sodium lights are very narrow and easily filterable. High Pressure Sodium lamps have other elements (mainly Mercury) that emit at other frequencies and make filtering the light from them more problematic. – Michael C Oct 26 '14 at 2:23
  • @MichaelClark that is still reflected in the graph - its not just LPS that is the blue line but all other light pollution, including HPS and metal halide sources. The specific yellow cast those lights have are from the sodium lines, which filtering may have the ability to reduce. It won't be perfect, but it can help. – user13451 Oct 26 '14 at 2:29
  • Can you add your own lights? – mattdm Oct 27 '14 at 0:12
  • @mattdm - The space is tight but it may be possible to add at least one, possibly two. I can use a flash as well. – L84 Oct 27 '14 at 6:34
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You will have to sit down and work on it. A simple 'adjust the white balance' approach will not work, because the light that you are getting is not from a black-body source for which color temperature has meaning. You are working with specific frequencies of light from a fluorescent or discharge source. As such, you need to look at steps to getting that light into something that approximates a traditional blackbody curve that you can work with.

The ideal case would be to turn off all the HID lights, put on some broad spectrum or incandescent lights into the scene, or photography by daylight. That way, you don't have to worry about the frequencies of the specific light and can carry on as normal. This probably isn't the case.


A quick and simple thing to try (I make no guarantees that it will work) is to use a didymium filter that can take a chunk of the yellow that is associated with the sodium line out of the image.

For sodium vapor (a significant portion of light pollution for night photography), you've got:

The red line is a filter known as a didymium filter and it does a good of at blocking the yellow from the sodium line. It will also block some of the other light around it. This particular filter is also known as a 'red enhancer' and can be commonly found in photography stores. Its something to try, though I won't guarantee that it will work, but it's a relatively cheap approach for a single filter that might work for what you are after.


Ok, the didymium filter didn't work to the degree that you wanted.

Lets look more closely at some examples of a metal halide light's spectra:

metal halide

enter image description here

and compare it to the sun:

enter image description here

You will see that the sun is relatively smooth (it has some narrow gaps that correspond to the absorption of specific elements). Thus the ideal is to reduce those strong, preferably as narrowly as possible (though this may not always be an option).

Working from page 16 of Rosco Filter Facts mentioned by Iliah Borg in another answer, we've got the 'lamp groups' in the 'D' section. Note that the low pressure sodium (which would be the easiest to block) is also the least likely that you have there. You are interested in the 'discharge lamp to daylight' (5500K) or 'discharge lamp to tungsten' (3200K). The filters will then correct. Note that its often a fair bit of filters you're going to be stacking on this. You're looking at a CTB and Minusgreen filter in most cases as described in the page.

The 3/4 CTB has a mired shift of -100. While you may not be able to find the Rosco product 3203, a -100 MIRED filter is half way between an 80C and an 80B filter. You could likely use either of those, or stack an 80B with an 82A which is a -21 MIRED (the MIRED shifts can be added so a -81 (80C) + -21 (82A) gives you a -102). Note that this will cost you about 1.3 stops of light - make sure you have a tripod. Note that you may be able to use the color temperature adjustment in the camera or post to account for this correction (though how to use/understand mired for making adjustments from one temperature to another could well be its own question).

The other component that is seen is a minus green. These are CC series filters. A CC30M is a filter that is magenta in color and has the effect of removing the color directly opposite it on the color wheel, in this case, green.

Ideally, you will get several of these filters (the 80 series and some CCMs) that you can have in combination and can stack as appropriately to get the right color.

The spectrum of the CCM series filters can be seen:

CCM filter

Note that this graph is showing density rather than transmission and is blocking the violet and some of the green and yellow while allowing the blue and red light to go through.

I will point out that his may not be sufficient to just use a CCM filter (some of the lighting combinations in the Rosco document had more complex lighting combinations. From an old document that Kodak had for filters under HID lighting it had this table:

       | High Pressure | Mercury | Metal Halide | Metal Halide
       | Sodium 2700K  | Vapor   | 4300K        | 3200K
-------+---------------+---------+--------------+-------------
(print)| -             | -       | -            | -
 Porta | -             | -       | -            | -
  160  | 50B+70C       | 30B+05C | 05C+10M      | 80C+10M
  400  | 50B+70C       | 30B+05C | 05C+10M      | 80C+10M
  800  | 60B+50C       | 30M     | 05R+20M      | 20B+30C
 Supra | -             | -       | -            | -
  100  | 55B+50C       | 30M     | 50R+20M      | 50C+20M
  400  | 55B+50C       | 20B+30M | 30M+05Y      | 30B+05C
  800  | 60B+50C       | 30M     | 05R+20M      | 20B+30C

For the 3200K metal halide working with a specific film, it was suggesting an 80 Cyan and 10 magenta filter or a 20 blue and 30 cyan, while a high pressure sodium light needed 50 blue and 70 cyan correction. Note that this table is for specific film emulsions - a digital sensor may very well be different.

Next, you would take a photograph of a gray card. With the information from the gray card, you can look at the histogram provided and see if the R/G/B channels are appropriately balanced with each other. If there is too much blue, back off on the 80 series. Too much green? Add some more magenta. Its like leveling a tripod... except with color - and its much easier to work with it in post if its all balanced out before hand rather than trying to correct it later.

You may wish to get a color checker card. This way, once you get the histogram close enough, you take a picture of this can then do additional corrections in post production against specific known targets.

One of the important things to note in all of this is that you cannot remove specific frequencies of light in post production. You can alter entire channels, but you can't go back and say "you know, there is too much light from the 589nm source, lets cut that back." That is something that is best done with filters.

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  • Thank you for the detailed answer. I think you also help me understand why I can fix some photos and not others...because of the specific frequencies. – L84 Oct 26 '14 at 4:25
  • Is it an option to use flash to compensate for the deficiencies of the available light spectrum? Or maybe halogen work lights? – Iliah Borg Oct 26 '14 at 12:53
  • Michael, Rosco will be at PhotoPlus Expo, booth 165. They usually give away swatchbooks with filter samples, rosco.com/sbreqs and it is a good way to try and see which filters fit. Lee Filters are yet another source. – Iliah Borg Oct 26 '14 at 13:00
  • @IliahBorg using additional light sources can help if they are able to become a significant source of illumination compared to the other light sources. However, the other light would still be present and causing color tints. If the light source isn't an incandescent or well calibrated broad spectrum, you would then have its additional peaks in the spectrum to deal with. – user13451 Oct 26 '14 at 18:14
  • Dear Michael, I know how these things work, 40 years of trade helps learn a thing or two ;) Even 30% of auxiliary full spectrum source helps significantly, filling voids. – Iliah Borg Oct 26 '14 at 20:39
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In the case of the Sodium Vapor lamps, set your Color Temperature to 2700°K. That is the center of the narrow band that those type lights emit. Some advanced High Pressure Sodium lamps include mercury that allows them to emit a slightly broader spectrum, but it is still centered at around 2700°K.

Metal Halide lamps can be tuned from around 3000°K to over 20000°K. My experience with those used in amateur sports stadiums is that they are usually centered at around 3900-4200°K.

Keep in mind that many RAW convertors (including Adobe products such as Lightroom) ignore the in camera WB settings. You'll need to specify the color temperature when you open the photos in your RAW convertor. An easy way to do this with multiple files is to create and use a preset from within your RAW convertor.

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  • > many RAW convertors (including Adobe products such as Lightroom) ignore the in camera WB settings. - Dear Michael, that is not so. "As shot" WB settings in raw converters take WB values from the camera. – Iliah Borg Oct 26 '14 at 13:11
  • @IliahBorg A few do, but most don't - especially if the custom WB or WB bracketing info is written to the maker note section of the EXIF info. Adobe Camera Raw, the conversion engine used by LR and PS, which is probably the most used RAW convertor on the planet, ignores the maker note section of Canon .cr2 files. If I select 2700°K and add a +2B/+3G WB shift , LR ignores the fine tuning. – Michael C Oct 27 '14 at 4:30
  • Dear Michael, If you select CCT and shift, Canon cameras recalculate WB coefficients and records them into metadata. Lr/ACR use those WB coefficients, same as DPP and in-camera engines. That has noting to do with makernotes. As to Adobe not reading Canon makernotes - it is not so. For example, the calculation of baseline exposure compensation is based on makernotes tag 0x01fd. – Iliah Borg Oct 27 '14 at 14:29
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Your best bet here is a custom white balance. On most Nikon cameras, there's a custom white balance setting, typically denoted by a "K". In this case it depends on the lights in use, but something around 3000K would be a good start.

I'd recommend using a grey card, white piece of paper or your hand (worst case scenario) to be used as a reference under the same light before you start shooting the plants. This way, you can figure out a white balance that is close, dial it in, and adjust if need be.

That being said, I've had pretty good luck with Auto White Balance (AWB on the white balance settings), which is certainly worth a try here.

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Shoot in RAW format and fix in post-production. When importing RAW, you can adjust the color temperature. If that doesn't fix it, use a layer mask and a selective color adjustment layer in Photoshop to correct the color cast(s).

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Rosco Filter Facts brochure has a chapter on filters for improving photos under discharge lamps, page 14.

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    If the brochure goes offline there is no easy way to retrieve the information. Can you explain how to prevent yellowing in this answer making it future proof? – Hugo Oct 26 '14 at 7:05
  • Let's give a change to Iliah to improve this answer (great info in the PDF!) before flagging this answer for deletion... – TFuto Oct 26 '14 at 8:25
  • I do not see any way to improve the answer. It is a violation of copyrights to include long and direct quotes from technical brochures. Rosco going offline is no more likely than Broadway stopping production. – Iliah Borg Oct 26 '14 at 11:50
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    @IliahBorg The exact phrases are copyrighted, but the underlying ideas are not. Working these ideas into your answer wuould in my opinion greatly improve it. – Hugo Oct 26 '14 at 19:04
  • Dear Hugo, the ideas are from any decent textbook on physics of light, should we go down to axiomatics than? The question was well-formulated, with good knowledge of the problem. I try to avoid insulting people explaining banalities. – Iliah Borg Oct 26 '14 at 20:41

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