On 2001-09-02 10:44, Tomaz Klinc wrote:
The question is: "Does SF have an 'Internal Colour Space,' as claimed by
the Manual on p. 30, and implied by the CMS dialog?".
Hmmm, which internal? Scanner Internal, Internal Monitor, Internal Output, or Internal within the Profiles for ICC/ColorSync. I suspect you mean the latter and if so:
Only if you select one and to avoid potential mismatches it should be the same as you use in Photoshop. Photoshop 5 users really shouldn't even condider an alternative, but PS6 users can in "theory' pick anyone they like and PS6 will ensure that the displayed image is colour accurate. However, I'm not convinced (given the number of questions here and in my private email) that folk actually appreciate the differences between PS5 and PS6 in this regard.
Granted that I don't have the slightest idea how SF operates
internally, I still feel confident that the right answer is an emphatic
"No!", if the term 'color space' is to be understood in it's usual
sense.
How can you write this - surely to goodness you can see that selecting a profile in the Internal field has an impact.? I'll explain how you can test this in a moment.
What SF most probably does have internally is something that could be
called a "Face-value color space," that simply says "This color is
exactly what it purports to be." In other words, mathematically
speaking, SF's 'Internal Colour Space' is the identity maping, which is
no color space at all.
I don't know what this means.
So, what is "this color" that SilverFast gets from the scanner and
interprets at it's face value. It is the color value sent by the
scanner and subsequently modified, or interpreted, in accordance with
the calibration standard. When this value is output by SF to another
device, it is modified, or maped, or 'tagged' again, so that the
device could understand it correctly. In this scheme no proper SF
"internal colour space" would serve any purpose.
The colour space is either nothing or something - there is NO in between. It either does something or nothing - there is NO in between. The data gets mapped from the scanner colour space to the colour space defined by YOU in the Internal popup - the destination profile. If you leave it as None a colour conversion will not take place since there is no destination. But profiles are useless without a Colour Matching Module to carry out the transforms.
Try the following (I really hope you're pulling my leg):
Set PS6 set to use Adobe RGB as your working space. Open Silverfast:
Open the Silverfast CMS dialog and set as Scanner Internal and Internal Monitor to None. Also set Scanner (R or T) to None and Internal to None. Now click Apply and and make a Prescan of an image that has plenty of colour.
Once the image is displayed in the Preview hold down the Shift Key and mouse click 4 areas of the image, ideally 4 different colours. Write ALL the RGB values associated with these 4 sample points down.
Now open the CMS dialog and set Scanner Internal to Calibrate You have Assigned the scanner profile! Click Apply and make another prescan. Check and note down each of the sample point RGB values. They will NOT be the same as they were before.
Open the CMS dialog again and set Internal Monitor to Automatic - click the Apply button - the appearance of the image should change. Make sure you do another prescan. Again check and note down each of the RGB sample point values. Did they change from the last set.
Open the CMS dialog and set Internal to Adobe RGB, click Apply and then make another prescan. Check and note down the 4 sample point RGB values. They "may" be different to previous set. In my case the difference was 1 unit in the blue channel on two sample points and 2 units on green channel for one sample point. no image will be the same - but major changes should not occur.
Open the CMS dialog again and change Internal from Adobe RGB to sRGB, click Apply and again make another prescan. Check and note down the RGB sample values and this time you should see a pretty big change relative to Adobe RGB.
(added text: I find that 1 sRGB profile from a batch of 3 gives me the same RGB values as Adobe RGB - I will need to check what is going on with this profile, which is supplied by apple as part of colorsync)
Open the CMS dialog and change Internal to read ColorMatch - now you have a different set of XY coordinates and a different gamma snapping at your backside. Click Apply and again prescan. Check and note the RGB values. They will again be different.
Internal either does something or nothing - you should have noted :-
As you moved through all the various working spaces Silverfast did its best to retain the appeance of the image and it did so by changing the RGB values - this is EXACTLY what Convert to Profile in PS6 does. This is Colour Management at work!
Internal scanner = Assign Profile and Internal = Convert to Profile. You need BOTH to ensure that the image matches the original when it gets delivered to Photoshop. If Internal Scanner is set to None Internal becomes Assign Profile. They even gave us all the options for Rendering Intent so that we can optimise the conversions from source to destination.
All of this may be what you meant by your last paragraph but your first has an entirely different meaning, hence my ramblings.
Ian
(tried to fix my spelling also deleted some silly remarks and smillies)
<font size=-1>[ This Message was edited by: ilyons on 2001-09-02 16:24 ]</font>
<font size=-1>[ This Message was edited by: ilyons on 2001-09-03 00:35 ]</font>
