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what color space to use?

(2007-06-05 22:04:10) 下一個

Use sRGB :The printers in most commercial labs, such as whcc, Mpix, ezprints (our lab), Shutterfly (whom we used to use), Kodak, Fujifilm, Photobox, Costco, Snapfish, Wolfe's, etc., shine light on photographic paper, similar to the way film prints are made. They have similar color range to the sRGB color space. Most of them expect your file to be in sRGB and if it isn't, your prints will look washed out.

Use Adobe 98: If you have a photo with colors that fall outside the sRGB range that are important to render accurately, and you have an ink-jet printer that can render them, Adobe 98 is a better choice than sRGB (and ProPhoto is even better). Adobe 98 is also better if you have a commercial client, such as a magazine, that requests it in Adobe 98. But for most photos of people printed at commercial printers, sRGB is a better choice. And if you want them to display well on the Internet, it's the only choice.

a camera can capture colors fall outside the range of sRGB and Adobe98

The box of crayons you're given for displaying photos on the web is called sRGB.

There are other color spaces, such as Adobe RGB (1998), but no Windows-based browser can display them correctly. The Macintosh browsers Safari and Internet Explorer can, but only under conditions not normally found in everyday browsing.

Adobe 98 is broader, meaning it spreads its crayons across a broader range of colors by making the jump between each color more coarse.

You get finer increments of skin tone by using sRGB, for example. But the pure cyan in HP's original logo can only be accurately represented by Adobe 98, whereas in sRGB you would have to pick a substitute color.






http://forums.dvdoctor.net/showthread.php?t=33925
sRGB being the colour space to use unless you want to end up with a CYMK file output.

As your monitor (unless you are looking at one cost several thousand pounds) can only show sRGB you can never actually see what an Adobe RGB colour space is. OK, we accepted that. The part that was a surprise that no printer (and they said NO printer) can at present time print out at anything other than sRGB. To print from any other larger colour space it has to convert to sRGB and some printers are not very good at it. They therefore used the logic that in such cases it seems realistic to keep in the one cplour space right through from Capture - Edit - Print. (which incidently was the name and subject of the seminar)

I have always believed, many from top grade books and articles and not least from the people who have produced printer profiles for me , that at least a colour space of AdobeRGB was best to use. Reading certain reports includeing those about the Epson R2400 which I am waiting delivery of, can handle large colour space. But, it is never as far as I can see, actually stated as such. I have since realised that the main sponsor of this seminar was HP and I seem to recall reading that they are trying to establish the sRGB as a general colour space to use for all digital photo work. The reps HP comment at the Seminar to me was that their printers, even the very top of the range printers costing thousands of pounds, only printed out in sRGB. He showed me prints that were on display there which were printed from a sRGB and other larger RGB colour space (the same photo in A1 size) and pointed out that HP printers performed the conversion to sRGB very well, much better than most other brands, includeing Epson.


sRGB means two separate things, one good and one very good.
==
Primaries
The sRGB promaries are those of ITU.rec 709, the primary set for "new and emerging television services". That means digital HDTV to most of us. The red and blue primaries are identically those of the EBU (PAL) colour system, and the green primary lies within the tolerance box for EBU(European Broadcasting Union ) green.

This means that sRGB pictures will look right when you see them on tv, any tv anywhere in the world, provided that tv makes good tv pictures (not all do that, because manufacturers tend to use desaturated primaries in order to get more light, but it's true as a generic statement).

Transfer Characteristic (Gamma)
sRGB uses a far more powerful law than does television, with a much steeper slope near black. So it reveals detail in shadows, and presents saturated colours, much better than does television. That's fine for stills, where noise is stationary, but is hopeless for video where the head-amplifier noise would prevail.

So, sRGB makes a lot of sense if your pictures are going to be viewed on a tv set, anywhere in the world. To a large extent, that includes computers since computer displays mostly use primaries that are pretty close to sRGB or TV (if they didn't, you would have noticed when editing video).

The only issue is the printers. Printer primaries are synthetic since they are generated as secondaries (YMC) rather than primaries (RGB), and they depend on the illuminant (the light under which you view the results). So the printed image is far less controllable than the image on-screen. In general, we assume an illuminant of between D50 and D65 (daylight), but much of printed work is viewed under tungsten or fluorescent lighting, where are the rules get broken.

sRGB is a good way to standardise colour reproduction. It works and is ubiquitous.

====
 As regards photography I feel I will keep to using Adobe RGB. I have however found that the sRGB colour space can be better for skin tones and as most of my work is with portraits will use it at times. Someone at the seminar said just remember sRGB could mean studioRGB, although of course it does not, it is something to use as a prompt!!

==========

sRGB was introduced as an attempt to unify the multi-media world, that means, tv, computers, and print. Given that tv is the dominant distribution means for electronically produced content, it made sense to unify with it.




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