Scanning using larger color spaces than the Adobe RGB (1998)

[micheleberti]

I read this point somewhere and I wonder why this could be a good

choice. 1) What are the advantages of scanning with a larger color

space if then a lot of colors cannot be reproduced by a printer

device? 2) What color space are u using with your scanner?

[cosmic_c]

An interesting question but you are assuming that colour spaces and output printer profiles all neatly fit within each other. What you will find is that bits of the printer space are outside the area covered by some profiles even though the colour space might have a larger volume than the printer. So if use a working colour space that does not include ALL parts of the output space, you will not be able to faithfully reproduce some colours contained in your image. Quite often it is not an issue for some images.

[micheleberti]

<blockquote>"<i>So if use a working colour space that does not include ALL parts of the output space, you will not be able to faithfully reproduce some colours contained in your image</i>"</blockquote> <p>Yes I agree, In fact the doubt behind my question arise just from this fact, so I wonder why should I use a larger color space ...

[ellis_vener_photography]

The obvious advantage is to get all of

the color information in the original piece of film, to make an accurate digital reproduction

of the film you are scanning. Once you have that in the scan you can then use it to shape

the information going to the printer. Will you only print the image once? I doubt it. Your

skills are going to get better as you go on and your physical tools will evolve too.<P>

 

I use "Ekta Space PS5, J Holmes" as a workspace for scanning (workspaces are device

neutral color spaces -- Adobe RGB(1998) ,sRGB and Pro Photo are others) and you can

download it from <A href = http://www.josephholmes.com/profiles> Ekta Space </a>.

Included in the download is a very informative pdf which answers your question in much

more depth than I have space or desire to do here.

[micheleberti]

Thanks for the link Ellis, i will read that document.

[gilou]

Hi Michele

 

by default it is recommended to use Adobe1998 Color space as working space. However, your scanner or digital camera could have a wider color space than adobe1998. (this is my case with the Minolta5400).

If You scanner color space is smaller than Adobe1998.... then use it. Otherwise try something like Prophoto.

to compare Colorspaces ... use this link : http://www.iccview.de/

and you will be able to compare the color spaces (scanner Device versus Working space)

On My side I use Prophoto, but when I want a file to be printed in shop, I convert it to SRGB or Adobe depending on the ability of the "Printer".

 

brgds -Gilles.

[gilou]

Here is a comparison of my scanner colorspace vs SRGB.

the Solid part represent the Scanner Colorspace, and the lines represent the SRGB color space.

As you can see, If I use SRGB with My scanner, i will not retreive all the information provided by my scanner. In fact the colors will be coneverted with a certain loss.

Hope I'm clear.

[micheleberti]

Gilles, I use a Nikon Coolscan 5000 ED and in my understanding its 'input profile' is fixed and installed during the setup of the driver. But how do I know if is wider or smaller than, for example, the Adobe RGB 1998? From the link you provided there is not the ICC profile of this scanner ...

[gilou]

hi Michele,

 

You can either use the icc file provided by Nikon (I suppose) or profile your scanner with targets (Kodak or Fuji or wolfaust ...) and use the created profile.

However knowing the "category" of your scanner, I can easily tell you that your scanner space is much wider than SRGB, and maybe wider than Adobe, but as I don't know exactly Nikon Scanner .... Not 100% sure...

 

brgds -gilles.

[micheleberti]

Ellis, how can I use that color space with my scanner? The scanner software I am using (Nikon Scan 4.0) doesn't allow to pick a particular color space different from those that are already in a list (see attached picture).

[roger_smith4]

Michele, I'm not familiar with the Nikon software, but after you download a new color space, you need to copy it to the right folder. In Windows XP it's in c:\windows\system32\spool/drivers\color.

After you do that, the new space should show up in your scanner software. Personally, I scan and convert to AdobeRGB. My scans all end up as SRGB before going to the printer, so I don't think I'd benefit from a larger space. I only use Adobe on the chance that some day I'll have a wider-gamut output device.

[cosmic_c]

Michele - I use a Minolta scanner so am not familiar with the Nikon, but they probably work in a similar way for colour management.

 

Looking at the options displayed, I assume that ScannerRGB is the Nikon profile for the scanner and gives the best the scanner can generate. So select that (ScannerRGB) and when you open the image in Photoshop assign ScannerRGB to it (if the file was not tagged) and then convert to your work space eg ProphotoRGB or Ectaspace - can do all that in the open dialogue if you set the colour preferences that way.

 

Alternatively, scan with Nikon colour management turned off and assign the relevant positive or negative scanner profile when opening the file in photoshop, then convert to the colour space. Its all done on opening the file. That is what I do with the Minolta 5400 and seems to give me my best results.

[cosmic_c]

I should have added that the advantage of keeping the scanned image in the scanners native colour space/profile is that you do not degrade it by converting it to another colour space. For example, had you scanned all your images as AdobeRGB or sRGB and now decided to use ProphotoRGB, those scans would have to be redone because you have lost the colour information. Had you scanned them to the native scanner work space, then its just a different conversion on opening the image.

 

Hope that helps

 

Costas

[emre]

You have to convert to the working space anyway (scanner's color spaces are not necessarily welll-behaved), so you might as well pick the right one. That means the smallest one wide enough to capture all the colors in the image.

[micheleberti]

... but from a pratical point of view which is '<i>the smallest one wide enough to capture all the colors in the image</i>'?

[emre]

Enable the gamut-clipping warning in your RAW converter and voila. If you can't do that, use the highlight-clipping warning. In practice, saturated colors are bright too, so look for clipped highlights. If moving to a wider color space eliminates the clipping, you know you hit the gamut boundary.

[emre]

We are talking about scanning... I completely forgot. Then use a rule of thumb: Ektaspace or Prophoto for saturated slides if the scanner is 16-bit capable, and Adobe RGB for all else.

[gilou]

Emre,

 

That's my rule .... it is not a rule of thumb ....

 

8-).

 

Brgds -gilles

[ellis_vener_photography]

<I>Ellis, how can I use that color space with my scanner? The scanner software I am using

(Nikon Scan 4.0) doesn't allow to pick a particular color space different from those that are

already in a list</I><P>it'a problem with Nikon Scan. You'll have to use other scanning

software if you want to A,)

profile your scanner and b.) use another workspace. I use SilverFast Ai6

[micheleberti]

yes.... you anticipated me in the right way :-) Thanks Ellis

[ted_marcus1]

I've read a lot lately about large-gamut color spaces. While I can appreciate the advantage of working in a space that captures more of what a scanner or sensor records, I have trouble with it in practice. You're going to be outputting the image on an inkjet printer, a monitor, or a printing press. None of those devices can render the entire gamut of a large-gamut color space, so you're always at the mercy of the perceptual or relative colorimetric rendering algorithms to distort the out-of-gamut colors into something that can be reproduced. For that matter, almost all monitors are limited to the small sRGB gamut, so you can't even see those extra colors that you're working with.

 

The Adobe RGB color space seems to offer the best compromise. It's (supposedly) designed to capture the extra colors an ink-jet printer can reproduce beyond sRGB, but it's "close enough" to sRGB so it minimizes the rendering distortion. That could be why it's ubiquitous. But if I'm really missing something, I'd very much like the opportunity to be educated.

[gilou]

hi Ted,

 

You may have miss something .... 8-)

You use a large gamut color space to manipulate your photo and to store it.

But when you want to print it or post it on the WEB, you then convert your photo into the right colorspace (SRGB for internet).

The interest is to use the widest color space in order to modify your photo. For instance if you apply levels, or change the saturation or apply many filters, you will then may use more colors than what can be usable in a narrow colorspace, this will lead to stranges colors (especially in the dark areas).

However if you use a wide color space for the manipulation of your photo, you will not/less be limited.

Once you have done all your homework, you can then convert back your photo to what ever colorspace you want..... and you will not have stranges colors in the dark areas!

 

 

For a test : Use a photo with dark areas, use SRGB, apply a long list of changes then compare the result to the same photo manipulated in Prophoto and then converted back to SRGB.... I think you will notice the difference.

 

Hope I'm clear.

[gilou]

Ted,

 

However you are right, Adobe colorspace is good.....

 

Brgds -Gilles

[micheleberti]

Gilles, your last post is very interesting and worth a try I think... Do you have any example to show? Or might be some reference in the www?

[ellis_vener_photography]

You might be interested in the pdf's on color management that Andrew Rodney has kindly

posted on his website <A HREF = http://www.thedigitaldog.com>

www.thedigitaldog.com</A><P>

 

Andrew Rodney is a sometimes contributor to photo.net, a noted expert and lecturer in

these matters, and the author of <A HREF = http://tinyurl.com/aqdso> "Color

Management for Photographers"</A>.