Malcolm Nathan nathan-at-amai.co.uk (Nathan Gaydhani)::21/7/04::10:59 am:: GMT+0100
>Malcolm, > >I mainly shoot in available light at different locations and often find just >a grey card is not enough to get the best reproduction. >When I bought the Monaco profiling kit, it came with a standard IT8 chart >and the software to profile from it. All I do it to take a photograph of it >in the same lighting as my subject and then build a profile off it later. I >can then apply this profile to all the photos in that lighting condition for >perfect colour balance. > >Nathan. with respect, I think Gretag's new Profilemaker Pro 5 Digital Camera module is a bit more sophisticated. why? :- 1: using a superior chart: the IT8 chart was designed for visually checking scanner output when printed on press, with manual adjustment of the scanner to obtain a match - even for scanner profiling the IT8 has been surpassed. (the HCT). Gretag have a new Munsell chart for camera profiling, it's the result of some very extensive research specifically into digi camera profiling. 2: disadvantages of placing a chart:: placing any chart in a scene to be photographed is problematic for at least 2 reasons: A: the light actually falling upon the chart may not really represent that falling upon the scene generally (e.g. studio backlight?) and with a distant shot it may be impossible to place the chart at all. Plus, a chart has to absolutely evenly illuminated across all colours within fine tolerances, otherwise you'll get a pretty wierd profile. [if anyone is planing to write in here about uneven scene illumination being better characterised by an unevenly lit chart please think about it, it's not true.] B: say it's a sunset car shot, placing the chart and building a profile from it will <dial out> the warm light of the sunset. SO neutralising the light on a captured chart basis is not always the right thing to do. So, we ideally need to characterize camera behaviour well and use that characterisation (an icc profile) whenever we shoot. (Perhaps, since they differ spectrally so extensively, we will characterize with a variety of light sources = e.g. tungsten, flash,daylight, HMI). Gretag suggest we do this and that it's done in a controlled environment with a very evenly illuminated chart (even illumination is absolutely imperative). [Here I need to take a sidestep into printer profiling to assist my next point:: Sophisticated output [printer] profiling takes account of final viewing environment (illuminant) for printed work. In most cases colour management protocol considers it correct that prints are made to be viewed in D50 light (a variety of daylight). I set up an Epson 9600 with Proofmaster RIP for a Welsh archive and Photography gallery a few weeks ago. The exhibition space is lit with tungsten spots. As you may be aware, metamerism [or, more correctly = illuminant depenedent failure of metamerism] is a strong issue in such circumstances. Although the eye can, of course, account for the idiosyncracies of the lighting and see white as white, the inkset may misbehave. These particular tungsten lights made the midtones in mono images awfully pink. Gretag give us the ability to capture spectral illuminant data and to apply that to the profile. Note thaty it's spectral, not just colorimetric. The printed images at the gallery viewed in daylight now look just a little green in midtone, but appear perfect under the gallery lighting. So profiling can anticiapte and adapt for metamerism, but not remove it universally. Prints change - so do camera charts. back to camera profiling:: In camera profiling, Gretag offer the opportunity (with the use of a Gretagmacbeth eyeOne spectrophotometer and eyeOne share) to record the spectral characteristics of any actual ambient light. Now we can rebuild the camera profile made earlier using that spectral data. Just like the gallery prints but in reverse since spectral characterisation allows compensation for camera metamerism [failure]. In a situation where the standard profile (one we made earlier) does not just quite do the job, this specific adaptation of the profile will often make an incredible difference. Of course you'll still need to find a way of graybalancing (white balancing) the camera. Or, perhaps, you may a standard daylight whitebalance [e.g. in the case of a sunset scene where you actually want to retain the sunset feel (not an unusual requirement)]. Hope it helps I hope Thomas Holm at pixl may add some comments later since he was deeply involved in beta testing the just released Gretag software and chart. We showed it in an early form at our last seminar at Apple in Spring, people seemed impressed ;-) Regards, Neil Barstow :: Apple Solutions Expert :: colourmanagement.net Consulting in Imaging & Colour Management, custom profiling, training, seminars implementation :: WE RESELL :- Gretag+eyeOne :: basICColor Squid, Display etc. XRite. :: GTI viewing booths :: Epson :: Proofmaster RIP + ISO Proofing solutions www.colourmanagement.net/ :: www.apple.com/uk/creative/neilbarstow/ =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
