Thanks for clearly explanation, thanks.
--
Michael
2008/1/3, Moose <olymoose@xxxxxxxxx>:
>
> Richard Ociepka wrote:
> > Michael Wong wrote:
> >
> >> I have found there may be saved as RAW file by Nikon Scan & Vuescan. Is
> >> there any benefit for these RAW files?
> >>
> First of all, I don't know that opening them in anything other than
> VueScan is useful, as any other converter won't know what to do with
> them. What they are is the direct output of the scanner, without any
> processing by VueScan at all other than to put them in TIFF format for
> storage. He calls them RAW, as they are in some ways like a camera RAW
> file, being the unprocessed scanner output. But they are quite different
> too, as they don't know anything about the color and exposure parameters
> of the film that was scanned.
>
> As far as I know, their major advantage is in workflow. When scanning a
> roll of film, I scan to RAW first. That goes quite quickly, as VS
> outputs to file as it scans, so there is no processing overhead time,
> just one mechanical scan after another. Once I have the film all
> scanned, I then "re-scan" from the RAW files, previewing as a batch,
> making any adjustments needed to the previews, then scanning to ordinary
> TIFF and/or JPEG as a batch. The scanning, processing, writing takes
> time, but happily goes on in the background while I am doing other
> things, on the computer or elsewhere.
>
> I find this much more efficient than adjusting each preview from the
> film directly, then waiting while VS does the full resolution scan, the
> second scan for IR channel, the image and dust removal processing and
> writing the files before I can go to the next frame.
>
> The other advantage is that I can go back and "rescan" any frame or
> frames with different settings if I want to change something. So if most
> of the shots are under similar lighting and exposure, I may just set
> parameters for the first frame, which sets the default settings for all
> later frames, and do the batch scan without looking at each frame. If
> one or another frame needs different settings for best results, I can
> easily rescan from the file. I keep the RAW files until I'm completely
> finished working with that roll, then discard them. If I'm not entirely
> satisfied with any frames, and think changing the scan may help in the
> future, I keep those RAW files.
> > The ability to adjust the color temperature, saturation and contrast.
> >
> Weeeelll... Yes and no. No more ability to do so than in processing a
> TIFF file in ACR, PS, etc. It's not like a RAW file from a camera. The
> RAW converter can read from the camera file the color temperature the
> camera used in taking the shot, tell you what it is and allow you to
> adjust it directly to a known different temp.
>
> With a film scan, the scanner has no way to know what the color temp of
> the film was. So if you open a scan output file in ACR, for example, it
> can let you adjust color temp relative to whatever is in the scan, but
> not to a specific temp. You still need a reference of some sort.
> Shooting a WhiBal or other black-white-gray reference will allow
> adjustment pretty close to true color, but is only good for that.
>
> Creating film icc profiles(s) allows you to ignore color temp. Scan
> using a daylight profile and you get the color effect of other light.
> Magic hour light, for example, will come out correctly warm. If you want
> to correct light to look like daylight, make a profile for that light.
> So you may shoot at sunset, under mixed artificial light, etc. and it
> will look like daylight. With multiple profiles for different light with
> the same film, you can very easily adjust white balance when scanning
> from RAW files.
>
> I don't know of any way to take film and accurately end up with a file
> that you can simply slide the color temp slider on to hit a specific
> temp. BUT - using icc profiles is actually more accurate. Camera sensors
> are highly color linear, so simply adjusting a slider works well. Film
> is not as color linear. The curves of the different color layers are not
> exactly the same, so correct balance at mid tones may not, and usually
> doesn't, guarantee correct balance in shadows or highlights. Building a
> table of corrections at many points of color, an icc profile, is the
> best way to color correct film.
>
> Film and digital are very different technologies and simply require
> different techniques for optimal color management.
>
> I've posted this many times, but I think it's such a good illustration
> of the value of color profiles for film. The first or top image in each
> pair is the output frm VueScan using Neutral WB setting. Perfectly
> decent scans that may be fairly easily adjusted in an editor. The second
> image of each pair is exactly the same except that I used an icc profile
> in the scan process. There has been absolutely no editor processing
> other than to downdample for web display. As you can see, not only is
> color corrected for WB, but the tonal curve is corrected.
>
> This is the biggest time saver I know of in film scanning. Many, often
> most, images are ready to print/display without further work. AND it
> corrects the color better than anything else.
>
> Moose
>
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--
Michael
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