On 14/11/02 19:24, Duncan Lawson wrote: > Hi Neil > >>> Thomas Holm/Neil Barstow don't seem to deal with profiling SG >>> (correct me if I'm wrong guys) > >> oh but we do Duncan, it's a bit of a speciality for me - the SG >> workflow [with good preview]. >> spectrally measured profiling data allows the making of profiles >> especially suited for specific illuminants.
Yep, you're wrong. > > So will you profile for two different viewing conditions? Not customarily but if you need this of course we can do it. I'd equate it to this, if a client asks you to shoot a few different shots of a product you have a strong idea of how should be lighted and shot, all the other shots would be second grade right? Presumably if asked to make just one it would be the best it could be... I always try and talk my clients out of that situation. The situation is of course slightly different with profiles: When you measure patches, the light source used for doing spectral measurements is of a specific kind, and only that. The only way to change the definitions of the light source , semi-reliable, is to apply either a filter in front of the light source or apply a mathematic transformation emulating the wavelength response any given patch would have when exposed to a given lights source. All standard ICC profile measurements (to the best of my knowledge) is measured to be compatible with D50 light even if the light source in the spectro is different. It is possible to have a filter which will (sort of) emulate D65 for certain spectros, but nothing that will emulate tungsten light or fluorescent. That leaves the math. To be able to successfully apply a formula which will re-calculate the light source to emulate another light source you need some pretty accurate measurements of that light source. These measurements is performed with a spectro-radiometer (which you will find exclusively at a very large well funded universities specialising in colour theory, and on Bruce Fraser's desk). Other than that you need to do a lot of testing to work out whether or not you are successful, and maybe some tweaks of the measurements. So, essentially to be able to target a profile specifically to a particular light condition you need to be able to define the wavelength of the light in that particular room (and it had better not change during the day)... Simply tweaking the profile may be satisfactory for some but the large majority of critical photographers on this list wouldn't be satisfied in my experience. You may get away with a simple tweak on certain images, but others would just fall apart. All the profiles I generate, are created to appear correct in D50 daylight spectrum. I've figured out the "best" way to generate the profiles (for daylight) after doing hundreds of prints on many different printers, with different papers, ink sets, printer settings and after measuring the results on 4 different spectrophotometers, and visually evaluating prints. These prints has been evaluated in many industry standard daylight boxes, under fluorescent daylight tubes, Solux bulbs and even in real daylight <G>, until I found the preferred combination. I know many list members concur with my judgement. > Are there details of > this on your website. If not, can you send me some info - probably off list? Not much, but there is something in one of the documents on my site, I can't remember which though, and it's not really exhaustive information anyway. > > Don't know what the 'rules' are for discussing the pricing of one's services > on the list are. Discussing services is a semi no-no, however I feel this is of common interest so I posted on the forum. Best Regards Thomas Holm / Pixl ApS - Photographer & Colour Management specialist - Adobe Certified Training Provider in Photoshop� - Imacon Authorized Scanner Training Facility - Remote Profiling Service (Output ICC profiles) - Seminars speaker and tutor on CM and Digital Imaging etc. - Home Page: www.pixl.dk � E-mail: [EMAIL PROTECTED] -- =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
