using filters to desaturate picture?
Posted 28 October 2005 - 01:15 AM
I am shooting a project with Sony DSR 450, and I would like to know is there any filters can desaturate the picture without change in camera setting or color correction? thanks.
Posted 30 October 2005 - 08:34 AM
Posted 30 October 2005 - 01:19 PM
This is an old list that I've posted many times before:
The various methods used to achieve desaturation of color in motion picture photography are:
Art direction. The best way to control color is by using less color in costumes, set dressing, wall painting, etc.
Use a less saturated film stock. Current examples: Kodak 5277 (Vision 320T), 5229 (Expression 500T), Fuji F-400T. NOTE: there is generally a correlation between lower saturation and lower contrast and softer blacks, since the black density can affect how saturated we perceive a color to be (just as in painting - to make a color more pastel, we mix white into it.) The exception is when silver retention processing is used (see below.)
Filters. Filters that allow bright highlights to bleed (“halate”) or wash into the shadows not only lower contrast, but soften colors. Some types of light-scattering filters: ProMist, Fog, Double Fog, Low Contrast, GlimmerGlass, Smoque, Frost, Supra-Frost, UltraCons.
Smoke. Smoke has a similar effect to filters in that contrast and color are lowered because light is allowed to wash over everything. However, smoke is dimensional and affects objects in the background more than objects in the foreground due to the increasing density of the smoke that one is viewing the object through as it recedes from the camera position.
Lighting. The general rule is that frontal lighting emphasizes color; back or cross-lighting emphasizes texture.
Developing. Overexposure and pull-process developing can lower saturation and contrast a little.
Flashing. Again, like filters and smoke, flashing lowers color saturation by adding a wash of white light over the image, also lowering the contrast. The advantage of flashing over filters is that it doesn't soften definition or produce artifacts like halos around light sources. Flashing can be achieved through the lens using an Arri VariCon device (which fits into a 6x6 mattebox) or a Panaflasher (which fits over one of the magazine ports on a Panaflex.) Some labs will post-flash the negative before development but many do not like to get into this because of the chance of damaging the negative through over-handling, or making a mistake. You can also flash an internegative. Prints and interpositives can also be flashed, which lowers contrast by darkening the highlights, not lifting the shadows – it also slightly softens colors but not as much as negative flashing.
Exposure. Underexposure is not really recommended, but a thin negative printed up will generally produce weaker colors and blacks, plus show a lot more grain. Some slight overexposure usually increases saturation if the denser negative leads to printing down the image – but EXTREME overexposure will also wash out colors (and highlight detail unfortunately) because most of the picture information is placed along the flatter shoulder portion of the characteristic curve.
Using incorrect color-balance. When shooting in daylight on tungsten-balanced film, removing the 85B color-correction filter will create a very blue-ish image on the negative that tends to reduce the saturation in reds, including skintones. However, blues and greens will get more exposure and possibly more saturation. By leaving the final timed image on the cold side, you can also keep skintones desaturated.
Silver-retention processes. Generally done to the print, but some techniques can be applied to the negative. A certain amount of black silver normally removed in the developing process is left in the image, increasing contrast and blacks, but also softening colors. Skip-bleach / bleach-bypass, CFI's Silver-Tint, and Deluxe's CCE process are the most extreme techniques, leaving all or most of the silver in the print; Technicolor's ENR and Deluxe's ACE processes are more subtle, allowing the degree of silver retention to be modified. The greater the level of silver left in the film, the greater the desaturation. NOTE: Often a contrast-lowering technique like flashing, pull-developing, or filtration is used in conjunction with a silver retention process on the prints to keep the black levels and contrast to normal levels but also desaturate the image even further.
Optical printing. From the original color negative, both a color interpositive and a b&w positive are struck and then both elements are recombined (overlaid) in two exposure passes to create a new, desaturated dupe negative. How desaturated the image is depends on what percentage of the total exposure came from the b&w or the color I.P. "The Sacrifice" and "Sophie's Choice" (the flashbacks) used this technique; so did the opening scenes of "The Natural", which rephotographed the color record out-of-focus over the sharp b&w image, creating a diffusion effect.
Digital color-correction. Color intensity is easily manipulated in the digital realm. This is done all the time for film material transferred to video for television presentation; it can also be done for film that is scanned to a digital data format, color-corrected, and then recorded back to film (i.e. a digital intermediate.) For "Breaking the Waves", the Super-35 negative was telecine transferred to PAL D1 videotape, desaturated, and recorded back to film. Branaugh's "Frankenstein" digitally scanned the North Pole sequence into a computer and desaturated the image and output it back to film at full 35mm resolution. All of "O Brother Where Art Thou?" was transferred from Super-35 negative to 2K data files on a Spirit Datacine at Kodak's Cinesite, digitally color-corrected to desaturate some colors, and recorded back to film using a laser recorder. There have been many more examples of digital desaturation since this film.
All of these techniques can be combined in various ways – and usually are. Most productions trying to create a softer color palette always begin with the art direction and costuming. One reason is that it is always better to use the simplest means to achieve a goal. Another is that primary colors tend to desaturate less noticeably than pastel colors when using some sort of desaturation technique – and since skintones are generally pastel, they will lose their color much faster than a primary color in the frame. So controlling those colors in front of the camera is very important and allows you more options to alter the color with special techniques or processing without affecting the skintones too much.
Some examples of these techniques in use:
"Saving Private Ryan" was shot on 5293 pushed one stop to 400 ASA, flashed with a Panaflasher (generally), and used the ENR process on the prints. Some shots used filters or just foggy skies to wash out the image, plus the lens were stripped of their coatings to increase flare, and of course, the subject matter was naturally low in color saturation (overcast weather on a beach, actors wearing army costumes, etc.) Also, exterior scenes were shot with the less-strong 81EF filter instead of the 85B filter, creating a colder image.
Looking at DP Darius Khondji’s work, we see that "Seven" used negative flashing combined with Deluxe's CCE printing process. "Evita" used a VariCon and diffusion filters combined with a 30% ENR printing. "Alien Resurrection" used a 50% ENR printing.
"Ronin" used pull-processing of the neg combined with CCE printing.
"Heaven’s Gate" used negative flashing and print flashing together to soften the colors and contrast – plus a lot of smoke and dust in the scenes. "McCabe and Mrs. Miller", also shot by DP Vilmos Zsigmond, used underexposure, push-processing, negative flashing, and diffusion filters (mostly Double-Fogs).
"Kansas City" used Kodak’s EXR 5287 stock combined with CCE printing. (5287 has since been updated to 5277.)
"High Art" was shot on Kodak’s VISION 320T (5277) and flashed with a VariCon – but no silver retention printing techniques were used.
"Payback" used the CCE printing process, combined with shooting without the 85 filter outdoors on tungsten stock, and using a blue filter indoors – the overly blue image on the negative ensured that skintones would be consistently desaturated. This was combined with careful color control in the art direction – even yellow taxis and red fire hydrants were painted down. The print was timed to the blue side to keep any reds from becoming more saturated.
"Sleepy Hollow" used smoke on the sets and the CCE process in printing, plus a very monochromatic design.
Posted 30 October 2005 - 08:25 PM
Too, he's shooting on video, not film.
Posted 30 October 2005 - 08:46 PM
What you're describing is a fog filter, not a "color desaturating" filter. There would be a big difference between the two images!
Too, he's shooting on video, not film.
A fog filter DOES desaturate the colors in the image -- it just has additional artifacts as well, like halation, lifting the blacks, softening definition. But it does soften colors as well. You said that no filter can desaturate an image, which is incorrect. No filter can ONLY desaturate an image with no other artifacts; however, plenty of filters can cause some degree of desaturation.
And it does this regardless of whether you are shooting on video or film. The principle is the same: light scattering filters (or smoke, flashing, etc.) causes highlights to wash over shadows, making colors more pastel. It's like adding white paint into a color paint.
But if he simply wants less chroma intensity in the image without any other artifacts, then other than through production design, the most effective method is digital color-correction, regardless of whether the image is video or film. But as I said, some video cameras have this as a built-in feature; even some consumer DV cameras allow you to set-up some degree of color saturation, within limits.
Posted 31 October 2005 - 08:08 AM
I believe that is what he was asking about.
But if he simply wants less chroma intensity in the image without any other artifacts...
Posted 31 October 2005 - 12:00 PM
I believe that is what he was asking about.
Probably, but that's not what he actually asked. He never said he didn't want any other artifacts from the desaturation method, although I'm sure you're right about him not thinking that it's not as simple as a filter that only removes color. My point is simply that filters CAN desaturate colors, if you can live with a host of other artifacts as a result. In fact, there are a lot more methods of desaturation than there are for adding more saturation.
Posted 31 October 2005 - 05:11 PM
Who was it that said, "Listen to what I mean, not what I say."?
Probably, but that's not what he actually asked. He never said he didn't want any other artifacts from the desaturation method...
Posted 02 November 2005 - 03:28 AM
Thank you so very much for those wonderful information!! I think I am going to try glimmer glass since I would like to soften the actress's skin. BTW, do you have any suggestion for lighting a scene with a dark skin and white skin actors in a small space?? would I get the similar effect as black promist filter by netting the rear element of the lens? if so, could I also achieve the 'desaturated' effect I asked earlier? thanks.
Edited by Scott Mei, 02 November 2005 - 03:31 AM.
Posted 02 November 2005 - 01:21 PM
Honestly, since you are shooting in video, you should be doing the desaturation mainly with production design and digital color-correction tools in post, and by turning down the chroma level in your video camera. Use diffusion filters more because you want diffusion filter effects.
But yes, a GlimmerGlass combined with a Black Net may have a Black ProMist look, although a GlimmerGlass just combined with slightly crushing the black level in the camera or in post may also have a Black ProMist look.
Just make sure you are shooting wide-open or near wide-open, especially on wider-angle lenses, because the pattern in nets and the specks in glass diffusion, or bubble patterns, whatever they use, can start to come into focus on a consumer camera with small CCD's. With GlimmerGlass or Black ProMist, if you stop down too much, it will look like your lens is dusty.